Carlsbad City Council
October 21, 2025

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costs might also deter affordable housing projects, which operate on thin margins and frequently depend on government subsidies.72 Determining a range of costs for complete retention of stormwater is complex due to the wide variety of conditions. Costs vary widely across construction projects throughout California due to precipitation, size, soil types, topography, and other location-specific factors such as labor costs.

Two examples of costs to complete full retention of stormwater on a site with 16 acres of disturbed soil area (mean CGP size), based solely on the difference in precipitation, are as follows:

On a 16-acre project in the rainy North Coast region, a 2 year, 24-hour storm (2.93 inches of rainfall) would require a 148,900 cubic foot capacity detention basin, equivalent to a 29,780 square foot excavation at five feet in depth, including the required one foot of freeboard. A typical cost of $10/cubic yard for excavation73 is approximately $55,150, not including off- haul of spoils, if required. In addition, the basin would require engineered backfill if any roadways or buildings were subsequently constructed at the site, increasing the costs by $415,000 for import backfill and compaction (at $75/cubic yard).74 This scenario would therefore have a total cost of at least $470,150, since there would be additional costs for engineering design and final grading.

On a 16-acre project in an arid southern California region, the 2-year, 24- hour storm (1.72 inches of rainfall) for a similar level of retention would require an 87,400 cubic foot capacity detention basin at an excavation-only cost of $32,375. Using the same assumptions as above, engineered backfill would increase the total costs to at least $275,150.

The above examples show excavation and backfill costs only for a one-day design storm, and would add $3,000–$5,000 to the cost of each house in a typical residential development, depending on location (based on six houses/acre). However, an ‘atmospheric river’ storm lasting three days at the same intensity would require far more retention capacity, as the runoff coefficient would increase each day. In the northern part of the state, such a storm would necessitate an 893,400 cubic foot (33,100 cubic yard) basin, covering four acres at a four-foot depth and one foot of freeboard. The costs 72 Affordable Housing and Sustainable Communities Program. <https://www.hcd.ca.gov/affordable-housing-and-sustainable-communities> [as of July 19, 2022]. Provides an example.
73 Caltrans project 01-476604, Mendocino County, Item 044. <http://website.dot.ca.gov/hq/construc/estdet/01-476604-025.txt> [as of July 19, 2022] 74 Caltrans project 01-262004, Mendocino County, Item 072. <http://website.dot.ca.gov/hq/construc/estdet/01-262004-064.txt> [as of July 19, 2022] ORDER WQ 2022-0057-DWQ
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for excavation and engineered backfill would amount to $2.8 million.

Complete retention of stormwater for all construction sites regulated by this General Permit would be cost prohibitive.
· Active treatment: This approach would be to require the use of active treatment of all construction stormwater prior to discharge in areas with high quality waters. This approach may not be feasible because generally speaking, this permit may not specify the design location, type of construction, or particular manner in which compliance may be achieved with a requirement. (Wat. Code, § 13360.) In addition, active treatment is highly effective at treating water for TSS and turbidity, but generally does not remove pollutants that do not sorb to sediment, such as dissolved phase metals and hydrocarbon compounds. In order for this approach to be successful in guaranteeing no degradation of high quality waters, it would be necessary for active treatment to reliably treat all pollutants to levels that are equal to, or better than, the actual levels of each pollutant in each waterbody. Such limitations could only be established if the high quality waterbody and existing levels of each pollutant for which that water was high quality were known. As explained above, this data does not exist on a statewide basis. In addition, active treatment of all stormwater would likely be cost-prohibitive for some construction sites, because the cost of active treatment is directly related to the volume of stormwater that must be treated. For example, costs for a one-time use of active treatment systems ranges from $10,029 for 1.9 acres to $96,674 for 145 acres.75 However, current information obtained from staff conversations with an active treatment system vendor in the Sacramento area indicates that installed systems typically range from $70,000-$80,000 for a 200 gallon per minute seasonal system to $700,000 for a 2,000 gallon per minute seasonal system such as may be required to accommodate 3-inch storm events on a 16-acre site. Finally, based on staff conversations with the same active treatment system vendor and staff’s limited market search for additional active treatment vendors, active treatment systems are not evenly distributed throughout the state and there are currently an insufficient number of systems available to deploy to all construction sites during regional precipitation events.
75 U.S. EPA, Development Document for Final Effluent Guidelines and Standards for the Construction & Development Category (Nov. 2009) page. 9-35. <https://www.epa.gov/sites/default/files/2015-
06/documents/construction_development_dd_2009_chapters_1-11.pdf> [as of July 19, 2022]
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· Establishment of numeric effluent limitations for discharges to high quality waters: In order to prevent any degradation of any high quality water under this approach, the General Permit would have to implement water quality-based numeric effluent limitations that are equal to, or lower than, the actual ambient levels of each pollutant in each waterbody. Such limitations could only be established if the high quality waterbody and existing levels of each pollutant for which that water was high quality were known. As explained above, this data does not exist on a statewide basis. Even if the data did exist, it would not be possible to determine whether the methods to achieve compliance with the numeric effluent limitations would be technically or economically feasible at most or all construction sites. Further, because such numeric effluent limitations would necessarily be waterbody and pollutant specific, administration of such limitations would not be feasible under the General Permit structure.

Alternative 3 – Given the uncertainties about the locations of, and data limitations about, high quality waters, a third alternative would be to mandate specific requirements that would apply to all construction projects statewide. These statewide requirements could include more numeric effluent limitations, more stringent numeric action levels, or requiring the installation of specific BMPs, like active treatment.
· Require on-site stormwater retention for a compliance storm:

Because a prohibition on all discharges is not feasible as discussed above, one approach would be to require controls that eliminated discharges in most storms. For example, dischargers could be required to retain all runoff from the 95th percentile, 24-hour storm volume or the 85th percentile, 24-hour storm volume.76 Requiring all construction sites to install retention basins designed to retain all stormwater from large “compliance storms,” rather than complete retention from storms of all sizes, would encounter similar technological and economic difficulties as those identified above, just at a somewhat lesser scale. Considerations would have to include engineering design cost, available space for both the basin and excavation spoils stockpiles, avoidance of underground utility installations, schedule delays caused by constructing, using, backfilling and regrading the basin, off-haul of spoils and import of 76 Southern California Coastal Water Research Project. Concept Development: Design Storm for Water Quality in the Los Angeles Region, Technical Report 520, October 1, 2007, page 12.
<https://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/520_designSto rm.pdf> [as of July 19, 2022]. For example, a BMP sized to capture 90% instead of 80% of decadal runoff volume would require a BMP nearly triple the size.

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engineered fill, if required, disposition of accumulated stormwater or allowance for evaporation, vector control, and safety barriers. Further, there is no guarantee that the discharges from storms larger than the selected compliance storm would not cause degradation of high quality waters.
· Establishment of numeric technology based effluent limitations statewide: Even assuming that there might be a treatment technology that, if utilized, could guarantee no degradation of high quality waters, the State Water Board does not have the data that would be necessary to impose effluent limitation that would be derived from the use of that technology. In previous litigation, the superior court determined that the State Water Board did not have sufficient BMP performance data to impose technology based numeric effluent limitations for pH and turbidity for Risk Level 3 sites. Absent the development of this needed additional data, the Board would not be able to support the implementation of numeric technology based effluent limitations to prevent any possibility of degradation.77
· Active treatment: This option would suffer from the same problems identified for active treatment described under alternative 2, above.

Consistent with the Blue Ribbon Panel’s findings, active treatment is not feasible for all sites: “The active treatment systems have generally been employed on sites five acres or larger. While the systems are technically 77 California Building Industry Association v. State Water Resources Control Board, Sacramento Superior Court Case No. 34-20009-80000338-CU-WM-GDS.

Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category, 79 Federal Register 12661-01 (March 06,2014). The U.S.

EPA provides an explanation for not including a previous numeric effluent limitation for turbidity in its Effluent Limitation Guidelines for construction stormwater: “At this time, EPA is concerned that a numeric limitation may create a disincentive to green infrastructure techniques for managing stormwater. For example, meeting a numeric standard may require installation of a sediment basin or other impoundment on certain sites, which may be a disincentive to installing distributed stormwater controls. Also, EPA recognizes that additional data collection would likely be necessary in order to inform any establishment of numeric discharge standards and monitoring requirements in the future. At such time that EPA decides on a path forward with respect to numeric discharge standards and monitoring requirements, EPA will take appropriate actions to notify interested stakeholders. EPA encourages interested parties to continue submitting data and information to EPA with respect to numeric discharge standards at construction sites.”
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feasible for sites of any size, including sites or drainages as small as an acre or less, the cost may be prohibitive.”78
· Use of other, specific BMPs: Alternative 1 already requires the use of minimum BMPs such as non-structural BMPs (e.g., maintenance, good housekeeping, staff training/education, proper handling, spill response, project planning/scheduling) and source control BMPs (e.g., site design and planning, irrigation). This alternative approach would be to specify that certain additional BMPs would need to be used at all sites. This approach may not be feasible because generally speaking, as discussed above, this General Permit may not specify the design location, type of construction, or particular manner in which compliance may be had with a requirement. (Wat. Code, § 13360.) In addition, the efficacy of any structural BMPs are both site specific and pollutant specific, such that there are not universally beneficial BMPs that should be mandatory on all sites.

One of the first basic steps in creating a stormwater management plan is to assess site and watershed conditions. Site and watershed conditions include information such as geographic features or landmarks, drainage patterns, and general topography. Next, a plan should evaluate pollutants of concern and other additional benefits that BMPs can provide. Accordingly, the selection of appropriate BMPs is a highly site-specific inquiry. Because of the complexity of appropriate BMP selection, the permit requires a qualified stormwater professional to identify the appropriate site-specific BMPs and prepare the SWPPP. The General Permit imposes substantial education and training requirements for qualified stormwater professionals to ensure that the selection of site-specific BMPs is appropriate. (See General Permit, Sections V.C. – V.I.)
For example, bioretention basins are very effective for multiple pollutants, but are not feasible at many construction sites, as discussed in further detail in Fact Sheet, Section I.G.5.d. Media filters are another BMP that may be effective at removing multiple pollutants, but are already typically recommended by qualified stormwater professionals under Alternative 1.

Accordingly, requiring the universal use of specific structural BMPs for antidegradation purposes is not a feasible alternative because requiring specific BMPs may not be effective at reducing pollution and may not be technically feasible or cost effective depending on site characteristics. 78 The Feasibility of Numeric Effluent Limits Applicable to Discharges of Storm Water Associated with Municipal, Industrial, and Construction Activities, page 16.

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iii. Economic and Social Development Considerations and Consistency with Maximum Benefit to the People of the State
The State Water Board adopts the approach set forth in Alternative 1 for the General Permit. This alternative may allow limited and temporal degradation of high quality waters by construction stormwater discharges, but this alternative does require all construction stormwater discharges to not cause or contribute to exceedances of water quality objectives or interfere with the maintenance and protection of beneficial uses for high quality waters in all cases. Two of the approaches described under Alternative 2 would guarantee no degradation of high quality waters (i.e., construction prohibition and prohibition on discharges), but all of the approaches described under Alternative 2 are infeasible for the reasons described above and would hamper important social and economic development. The approaches described under Alternative 3 would not guarantee no degradation of high quality waters from authorized discharges, and are either technically or economically infeasible, or contrary to the framework of a general permit in which the methods for reducing or eliminating pollutants in stormwater discharges are developed by a stormwater professional and tailored to each individual construction site, or both.

The limited and temporal degradation of high quality waters that could occur under this General Permit is necessary to accommodate important economic or social development in the area and is consistent with the maximum benefit to the people of the state. Construction activities support important economic and social development. Construction is a large, vital industry in California, adding an estimated $240 billion in value in 2017 and a major source of employment.79 The U.S. Bureau of Labor Statistics estimates that there are 968,760 construction laborers in California.80 Construction projects include critical infrastructure (e.g., broadband 79 U. S. Census Bureau. Construction (NAICS Sector 23), (2017). <https://www.census.gov/data/tables/2017/econ/economic-census/naics-sector-

23.html> [as of July 19, 2022].

Legislative Analyst’s Office. CalFacts 2018. Construction is one of the major sectors for California’s 17 million jobs. <https://lao.ca.gov/reports/2018/3905/calfacts- 2018.pdf> [as of July 19, 2022].
80 U. S. Bureau of Labor Statistics. Occupation Employment and Wage Statistics, 47- 2061 Construction Laborers (May 2021).
<https://www.bls.gov/oes/current/oes472061.htm> [as of July 19, 2022].

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internet,81 roads,82 utility lines), public safety (e.g., flood control,83 system hardening84), restoration,85 housing,86 and commercial development. As noted by many commenters on the draft versions of this General Permit, California is facing a housing shortage.

Where there is a public utility, increased construction costs could be passed on by increased fees to utility users or road users. Higher construction costs could affect whether a housing project remains affordable.

Importantly, under Alternative 1, notwithstanding the possibility of limited and temporal degradation from some authorized stormwater discharges, the State Water Board finds that authorized stormwater discharges will not cause or contribute to exceedances of water quality objectives in high quality waters, and therefore will not cause pollution or conditions of nuisance or otherwise adversely affect beneficial uses of the receiving waterbodies. Because all beneficial uses will be maintained and protected, there will be only very minor impacts to water quality resulting from any degradation that does occur, so any resulting harm to the public interest associated with any degradation will also be very minor and speculative 81 State of California Executive Department. Executive Order N-73-20 (August 14, 2020). <https://www.gov.ca.gov/wp-content/uploads/2020/08/8.14.20-EO-N-73-20.pdf> [as of July 19, 2022].
82 State Highway Operation and Protection Program. Ten-Year Project Book, Fiscal Years 2021/22-2030/31. <https://dot.ca.gov/-/media/dot-media/programs/asset- management/documents/2022-q2-book-combined-a11y.pdf> [as of July 19, 2022]. 83 California Department of Water Resources. Small Communities Flood Risk Reduction. <https://water.ca.gov/Work-With-Us/Grants-And-Loans/Small-Communities-Flood- Risk-Reduction> [July 19, 2022].
84 E.g., Governor Newsom Signs Historic Legislation to Boost California’s Housing Supply and Fight the Housing Crisis (September 16, 2021). <https://www.nytimes.com/2021/07/21/business/energy-environment/pge- underground-powerlines-wildfires.html> [as of July 19, 2022]. In response to wildfires, utility companies aim to put power lines underground.
85 Southern California Wetlands Recovery Project. Work Plan 2020. <https://scwrp.org/wp-content/uploads/2020/04/Work-Plan-Report-2020.pdf> [as of July 19, 2022].
86 Office of the Governor. Governor Newsom Signs Historic Legislation to Boost California’s Housing Supply and Fight the Housing Crisis (September 16, 2021). <https://www.gov.ca.gov/2021/09/16/governor-newsom-signs-historic-legislation-to- boost-californias-housing-supply-and-fight-the-housing-crisis/> [as of July 19, 2022]. In 2021, Governor Newsom signed bipartisan legislation to expand housing production in California.

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because all high quality waters will still fully support all beneficial uses.

Therefore, it is not necessary to analyze the harm to the public interest associated with the authorized stormwater discharges, especially in a generalized and simple antidegradation analysis.
iv. Requirement for Highest Statutory and Regulatory Requirements and Best Practicable Treatment and Control
The permit requires the highest statutory and regulatory requirements and requires that the dischargers meet best practicable treatment or control and, as described more fully above, requires the following:
· Implementation of BAT/BCT/BPT, including compliance with U.S. EPA’s effluent limitation guidelines for the construction and development category as the level of pollutant abatement that is the best available technology economically achievable;
· Compliance with receiving water limitations;
· Enhanced requirements on non-stormwater discharges;
· TMDL-specific requirements that are consistent with the waste load allocations established by TMDLs that identify construction stormwater as a source; and
· Reservation of authority for the Regional Water Boards to retain the ability to impose additional sampling and monitoring requirements or coverage under an individual NPDES permit if necessary. v. Public Participation:

Numerous public participation opportunities have been provided during the development of this permit. In addition to the minimum public participation requirements required by the federal regulations governing NPDES permits and Water Code § 13167, State Water Board staff has met informally with stakeholders, held staff workshops, and accepted comments on an administrative draft of the permit.

I.I. Regional Water Board Authorities
Because this General Permit will be issued to thousands of construction sites across the State, the Regional Water Boards retain discretionary authority over certain issues that may arise from the discharges in their respective regions. This General Permit does not grant the Regional Water Boards any authority they do not otherwise have; rather, it merely emphasizes that the Regional Water Boards can take specific actions related to this General Permit. For example, the Regional Water Boards will be enforcing this General Permit and may need to adjust some requirements for a discharger based on the discharger’s compliance history.

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I.J. Construction Activities Covered
I.J.1. General Activities Covered
Construction activity phases (demolition and pre-development site preparation, grading and land development, streets and utilities, vertical construction, and final landscaping and site stabilization) can impact a construction site’s runoff sediment supply, pollutant loading, and transport characteristics. These modifications can occur both during and after the construction phase and, without proper controls, such as the requirements set forth in this General Permit, could result in significant degradation of the established water body beneficial uses in California. The primary stormwater pollutant at construction sites is excess sediment. Excess sediment can cloud the water and reduce the amount of sunlight reaching aquatic plants, clog fish gills, smother aquatic habitat and spawning areas, and impede navigation in our waterways. Sediment also transports other pollutants such as nutrients, metals, oils, and greases, and pesticides. In addition to sediment, other pollutants that are commonly associated with construction activities include, but are not limited to, pollutants from cement, stucco, paints, cleaning materials, general debris, chemicals associated with historical structures mobilized through demolition, historical contamination chemicals in soil mobilized by construction disturbance, and other construction related products easily transported by stormwater runoff. Dischargers can reduce and avoid the effects of these pollutants on water quality through better construction site design and use of best management practices (BMPs).
a. In accordance with the Ninth Circuit Court of Appeals’ decision in Natural Resource Defense Council v. U.S. EPA (9th Cir. 2008) 526 F.3d 591, and subsequent denial of the U.S. EPA’s petition for reconsideration in November 2008, oil and gas construction activities discharging stormwater contaminated only with sediment are no longer exempt from the NPDES program; b. Site geotechnical investigation work requires special precaution when backfilling bore holes so that aquifers are adequately protected from surface contamination;
c. Disturbances related to geotechnical or other site investigation work is a construction activity requiring permit coverage;
d. Construction activities that disturb 1 or more acres of soil associated with the construction of new fire prevention methods (e.g., fire barriers, fire breaks, and fire prevention areas) require permit coverage;
e. Stormwater discharges from dredge spoil placement that occur outside of U.S.

Army Corps of Engineers jurisdiction (upland sites) and that disturb one or more acres of land surface from construction activity are covered by this General Permit. Construction projects that include in-water work that require a ORDER WQ 2022-0057-DWQ
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Clean Water Act 404 permit should contact the Regional Board to determine whether a Clean Water Act 401 Certification is necessary; and f. Concrete mixing for the purpose of construction, in which all mixing activities occur solely within a specific project site, may do so under this General Permit.

The project site boundary are those as defined in the project’s site-specific SWPPP.

I.J.2. Linear Underground and Overhead Projects subject to this General Permit a. Underground and overhead facilities typically constructed as linear underground and overhead projects include, but are not limited to, any conveyance, pipe, or pipeline for the transportation of any gaseous, liquid (including water, wastewater for domestic municipal services), liquescent, or slurry substance; any cable line or wire for the transmission of electrical energy; any cable line or wire for communications (e.g., telephone, telegraph, radio, or television messages); and associated ancillary facilities. Construction activities associated with linear underground and overhead projects include, but are not limited to, those activities necessary for the installation of underground and overhead linear facilities (e.g., conduits, substructures, pipelines, towers, poles, cables, wires, connectors, switching, regulating and transforming equipment and associated ancillary facilities) and include, but are not limited to, underground utility mark-out, potholing, concrete and asphalt cutting and removal, trenching, excavation, boring and drilling, access road and pole/tower pad and cable/wire pull station, substation construction, substructure installation, construction of tower footings and/or foundations, pole and tower installations, pipeline installations, welding, concrete and/or pavement repair or replacement, and stockpile/borrow locations.
b. Water Quality Order 2003-0007-DWQ regulated construction activities associated with small linear underground and overhead projects that resulted in land disturbances greater than one acre, but less than five acres. These projects were considered non-traditional construction projects. Attachment E of this Order now regulates all construction activities from linear underground and overhead projects resulting in land disturbances greater than one acre. c. All disturbances to the ground must be accounted for and considered additive.

The following formula attempts to account for all disturbances from the construction activity, not just the trenching activity itself:

Total Disturbed Area = Wt*Lt + Ap + Db*Nb + Wr*Lr
Where:
· Wt is the width of the disturbance, including trench width, plus the immediate access width;
· Lt is the length of the trench or project pipe;
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· Ap is the area where project-related activity occurs (i.e., equipment and material storage, staging, and preparation areas not on paved surfaces, ancillary facility areas);
· Db is the bore hole diameter multiplied by the immediate access width; · Nb is the number of bore holes;
· Wr is the new road construction width; and
· Lr is the length of the new road.

This formula illustrates how to account for all disturbances to the ground resulting from the construction activity. Although dischargers are not required to use this exact formula, they must include all disturbances to the ground in their total calculation.
d. The visual inspection requirements set forth in Monitoring and Reporting Requirements in Attachment E are applicable to all linear underground and overhead projects regardless of type.
e. This General Permit’s visual inspection requirements apply to linear underground and overhead project Type 1 projects in both populated (developed or paved) and rural (undeveloped or unpaved) settings. In a populated environment, daily closure requirements for an open excavation may be an important element of a SWPPP for stormwater protection and safety plans because open excavations present a safety hazard to both pedestrians and traffic. However, uncovered excavations in rural settings do not pose as significant a threat to safety. Likewise, it makes sense for linear underground and overhead project Type 1 projects in developed settings to return disturbed land back to pre-construction conditions daily, because of incidental non- stormwater discharges in an urban environment and the associated potential for runoff from paved, impermeable surfaces. However, projects in rural settings, are less likely to have impervious surfaces and non-stormwater discharges and may not present the same threat to water quality.

I.J.3. Demolition
a. When a construction project involves demolition or renovation, construction and demolition debris is created. Construction and demolition debris can consist of three types of wastes:
i. Inert or non-hazardous waste;
ii. Hazardous waste as regulated by the United States Environmental Protection Agency under the Resource Conservation and Recovery Act (RCRA); and
iii. Items that contain hazardous components that might be regulated by the state.

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b. This General Permit requires best management practices (BMPs) to reduce the exposure of hazardous materials found in older structures from mobilizing in stormwater. Common hazardous materials related to demolition can be found on the U.S. EPA’s website87 and include but are not limited to:
i. Asbestos-Containing Materials
State of California Department of Industrial Relations Cal/OSHA has adopted regulations regarding asbestos exposure California Code of Regulations, Title 8, § 1529.
ii. Mercury Containing Devices
Many structures utilize devices that contain mercury. Mercury is persistent and toxic to human health and the environment. Mercury containing devices such as thermostats fluorescent lamps shall be isolated, removed and taken to an appropriate disposal facility.
iii. Lead-Based Paint
Older structures have a high likelihood of containing lead-based interior and exterior lead-based paint. During the demolition process the lead-based paint can be mobilized and behave like dust. The lead-based paint can be inhaled by workers on the demolition site and tracked off-site causing hazardous exposure to lead to the community. Therefore, it is important to minimize exposure by implementing lead-safe practices during demolition activities.
iv. Polychlorinated Biphenyls (PCBs) in Caulk
PCBs have been identified in caulk in many older structures. Protective BMPs and OSHA approved Personal Protective Equipment shall be utilized to prevent the exposure of PCBs to workers and the surrounding environment during and after demolition.

In order to be in compliant with all PCB TMDLs, Mercury TMDLs and statewide policies, dischargers are required to schedule demolition at times of the year with a low probability of a precipitation event, cover demolished material when activity stops for the day or prior to precipitation, or have a certified individual examine the structure for hazardous materials and mitigate the hazard with a method that prevents the material from discharging off-site.
87 U.S. EPA, Harmful Materials and Residential Demolition, <https://www.epa.gov/large- scale-residential-demolition/harmful-materials-and-residential-demolition> [as of May 20, 2021]
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Because of the production ban of PCBs in 1979, this General Permit has requirements for demolition of buildings built prior to January 1, 1980.88 I.J.4. Common Plan of Development or Sale
U.S. EPA regulations include the term “common plan of development or sale” to ensure that acreage within a common project does not artificially escape this General Permit’s requirements because construction activities are phased, split among smaller parcels, or completed by different owners or developers. The State Water Board is required to exercise its regulatory discretion in providing a common-sense interpretation of the term as it applies to construction projects and permit coverage. An overbroad interpretation of the term would render meaningless the clear “one acre” federal permitting threshold and would potentially trigger permitting of almost any construction activity that occurs within an area that had previously received area-wide utility or road improvements.

The 2008 U.S. EPA NPDES General Permit for Discharges from Construction Activity (2008 Construction General Permit) provided further clarification on the common plan of development or sale regarding non-contiguous construction activities. Where discrete construction projects within a larger common plan of development or sale are located at least 1/4 mile apart and the area between the projects is not being disturbed, each individual project can be treated as a separate plan of development or sale provided any interconnecting road, pipeline, or utility project that is part of the same “common plan” is not concurrently being disturbed.

For example, oil and gas well pads separated by 1/4 mile could be treated as separate projects. However, if the same two well pads and an interconnecting access road were all under construction at the same time, they would generally be considered as part of a single “common plan” for permitting purposes. If a utility company was constructing new trunk lines off an existing transmission line to serve separate residential subdivisions located more than 1/4 mile apart, the two trunk line projects could be considered separate projects.

Construction projects generally receive grading and/or building permits (Local Permits) from local authorities prior to initiating construction activity. These Local Permits spell out the scope of the project, the parcels involved, the type of construction approved, etc. Referring to the Local Permit helps define “common plan of development or sale.” In cases such as tract home development, a Local Permit will include all phases of the construction project including rough grading, utility and road installation, and vertical construction. All construction activities approved in the Local Permit are part of the common plan and must remain under the General Permit until construction is completed. For custom home construction, 88 Geosyntec Consultants for the Bay Area Stormwater Management Association.

Integrated Monitoring Report Part B: PCB and Mercury Loads Avoided and Reduced via Stormwater (IMR). 2013.

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Local Permits typically only approve vertical construction as the rough grading, utilities, and road improvements were already independently completed under the previous Local Permit. In the case of a custom home site, the homeowner must submit plans and obtain a distinct and separate Local Permit from the local authority in order to proceed. General Permit coverage for an individual homeowner building a custom home on a private lot of less than one acre is not required. Similarly, the installation of a swimming pool, deck, or landscaping that disturbs less than one acre that was not part of any previous Local Permit are not required to obtain General Permit coverage.

The following are several examples of construction activity of less than one acre that would require permit coverage:
a. A landowner receives a building permit(s) to build tract homes on a 100-acre site split into 200 one-third acre parcels, (the remaining acreage consists of streets and parkways) which are sold to individual homeowners as they are completed. The landowner completes and sells all the parcels except for two.

Although the remaining two parcels combined are less than one acre, the landowner must continue permit coverage for the two parcels. b. One of the parcels discussed above is sold to another owner who intends to complete the construction as already approved in the local permit. The new landowner must electronically certify and submit Permit Registration Documents to complete the construction even if the new landowner is required to obtain a separate Local Permit.
c. The landowner in (1) above purchases 50 additional one half-acre parcels adjacent to the original 200-acre project. The landowner seeks a Local Permit (or amendment to existing local permit) to build on 20 parcels while leaving the remaining 30 parcels for future development. The landowner must amend Permit Registration Documents to include the 20 parcels 14 days prior to commencement of construction activity on those parcels.

I.K. Construction Activities Not Covered
I.K.1. Traditional and Linear Construction Activities Not Covered Construction activities not covered by this General Permit are listed in the Order Section II.B and Section II.D.

I.K.2. Notice of Non-Applicability
Reliance on approved jurisdictional determinations is not allowed in the General Permit for a number of reasons. First, approved jurisdictional determinations delineate the scope of waters of the United States. They do not determine whether an activity results in a discharge to a water of the United States. Second, the scope of waters of the United States is subject to changes based on change of regulations or judicial decisions. Approved jurisdictional determinations are valid ORDER WQ 2022-0057-DWQ
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for a discrete number of years, and they may not be up-to-date with respect to implementing the current regulations if there is an intervening change during the duration of the validity of the approved jurisdictional determination. Finally, it is likely that the approved jurisdictional determination was requested by another party and in another context, such as the discharge of dredged or fill material. As such, the findings may not be easily extrapolated.

In 1998, the California Water Code was amended to require entities who are requested by the State Water Board to obtain General Permit coverage, but that have a valid reason to not obtain General Permit coverage, to submit a Notice of Non-Applicability (NONA). (Cal Wat. Code, § 13399.30, subd. (a)(2)).

The State Water Board considered allowing Entities to review United States Army Corp of Engineer approved jurisdictional determinations to evaluate, without a California licensed professional geologist, whether their facility location is within a basin and/or other physical location that is not hydrologically connected to waters of the United States. The State Water Board believes that this process can be difficult in some cases. In addition, there may be areas of the state that are not hydrologically connected to waters of the United States for which there is not a corresponding United States Army Corps of Engineer approved Jurisdictional Determination. Therefore, all “No Discharge” Technical Reports must be signed (wet signature and license number) by a California licensed professional engineer or geologist. In addition, the discharger must obtain a concurrence letter from the Regional Water Board that has jurisdiction over the site location.

I.K.3. Small Construction Erosivity Waiver
The U.S. EPA’s Stormwater Phase II Final Rule provides the option for a Small Construction Rainfall Erosivity waiver. This waiver applies to construction sites between 1 and 5 acres and allows permitting authorities to waive those sites that do not have adverse water quality impacts.

Projects that do not qualify for the Small Construction Rainfall Erosivity waiver include:
a. Projects that are part of a larger common plan of development disturbing more than 5 acres; and/or
b. Projects with construction lasting one year or greater.

Dischargers eligible for the Small Construction Erosivity waiver are exempt from coverage for this General Permit. The discharger must certify and submit to the State Water Board that small construction activity will occur only when the rainfall erosivity factor (“R” factor in the Revised Universal Soil Loss Equation) is less than 5 to obtain the waiver. The period of construction activity begins when the WDID number is issued and ends when the disturbed areas of the project meet the final stabilization conditions in Order Section III.H. The R value is calculated from the construction start date through all phases of construction (initial land disturbance ORDER WQ 2022-0057-DWQ
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through final stabilization). Small projects that are part of a larger plan of development (less than 5 combined acres of disturbance) use the earliest start date associated with the plan of development and their estimated time of meeting the final stabilization requirements.

Projects that qualify for the small construction erosivity waiver are not subject to the post-construction standards of this General Permit, but may be subject to existing permitted Phase I or Phase II municipal separate storm sewer system (MS4) post-construction requirements.

A waiver eligibility condition requires the operator to periodically inspect and properly maintain the area until the criteria for final stabilization defined in this General Permit is met. If use of this interim stabilization eligibility condition is relied upon to qualify for the waiver, a signature on the waiver with a certification statement constitutes acceptance of and commitment to complete the final stabilization process. The discharger must apply for a waiver in SMARTS prior to commencing construction activities.

U.S. EPA funded a cooperative agreement with Texas A&M University to develop an online rainfall erosivity calculator. Dischargers can access the calculator from the U.S. EPA’s website.89 Use of the calculator allows the discharger to determine potential eligibility for the rainfall erosivity waiver. It may also be useful in determining the time periods during which construction activity could be waived from General Permit coverage.

I.L. Obtaining and Modifying General Permit Coverage
This General Permit states the Legally Responsible Person (LRP) or a person legally authorized to sign and certify on behalf of the LRP is responsible for obtaining General Permit coverage. The LRP must electronically submit90 Permit Registration Documents prior to commencement of construction activities in the Stormwater Multiple Application Report Tracking System (SMARTS). Permit Registration Documents consist of:
· A Notice of Intent;
· A Risk Assessment;
· Post-Construction Calculations (when applicable);
· A Site Map;
· A SWPPP; and
89 U.S. EPA, Rainfall Erosivity Factor Calculator for Small Construction Sites, <https://lew.epa.gov/> [as of May 20, 2021]
90 Each signatory (LRP or DAR) must have an electronic authorization form on file with the State Water Board for each organization they represent in SMARTS.

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· The application fee.

A Waste Discharge Identification number (WDID) will automatically be emailed to the LRP once these components have been submitted and are deemed complete.

Failure to obtain coverage under this General Permit for stormwater discharges to waters of the United States is a violation of the Clean Water Act and the California Water Code.

The LRP is typically the person who possesses the title of the land, easement, or leasehold interest of the estate upon which the construction activities will occur for the regulated site. The LRP for linear underground and overhead projects is typically the person authorized to make management decisions of the utility company, municipality, or other public or private company or agency that owns or operates the linear underground and overhead project.

The Duly Authorized Representative is a person who has legal authority to sign, certify, and electronically submit Permit Registration Documents and Notices of Termination on behalf of the Legally Responsible Person.

It is expected that as the stormwater program develops, the Regional Water Boards may issue general or individual permits containing more specific provisions. If this occurs, this General Permit no longer regulates those dischargers obtaining coverage under those general or individual permits.

Any information provided to the Regional Water Board shall comply with the Homeland Security Act and any other federal law that concerns security in the United States; any information that does not comply should not be submitted.

Annual Reports must be submitted by projects that are enrolled under this General Permit for more than 90 days in a reporting period. The Annual Reports shall be submitted electronically in SMARTS. Annual Reports are due to the State Water Board by September 1st of each year with a July 1st through June 30th reporting period.

The application requirements clearly identify the responsible parties, locations, and scope of operations of dischargers covered by this General Permit and documents the discharger’s knowledge of the General Permit’s requirements. Regional Water Boards will enter their inspection and enforcement data into SMARTS.

Coverage under this General Permit remains in effect until a Notice of Termination is submitted in SMARTS and approved by the applicable Regional Water Board where the project is located. The discharger is responsible for any missed or outstanding invoices if the Regional Water Board denies the Notice of Termination. For outstanding invoices, a complete Notice of Termination must be received by the Regional Water Board 90 days from the original invoice date in order to cancel the invoice. The invoice is deemed valid and payable if a complete Notice of Termination is received after 90 days.

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This General Permit allows a discharger to terminate portions of a construction project if those portions have been sold to another owner. This General Permit is not transferable, so the new owner has the responsibility to obtain coverage, update the Stormwater Pollution Prevention Plan (SWPPP), and comply with General Permit requirements. The seller must notify the new owner about their responsibilities concerning this General Permit and must notify the State Water Board by submitting the new owner's name, address, and phone number on the Change of Information form for the termination to be processed. The seller must also disclose the state of construction, if construction activity is ongoing, or if the post-construction requirements are completed. The new owner for ongoing construction activity after the change of ownership is not exempt from this General Permit’s SWPPP requirements and must submit new Permit Registration Documents within 30 days of the date of change of ownership. The new owner is expected to review and update the existing SWPPP to ensure it is appropriate for the construction activity being undertaken.91
The Legally Responsible Person is always ultimately responsible for project compliance. This individual must certify the Permit Registration Documents and will be the recipient of any Notices of Violations or Administrative Civil Liabilities (fines) for the project.

The current annual fees are included in the Water Code fee schedule92 and are based on total disturbed area (acres) of the construction project. Projects continuing from the previous permit into this General Permit will pay the annual fees based on their current billing cycle.

Consistent with the 2022 U.S. EPA NPDES General Permit for Discharges from Construction Activity, this General Permit requires the discharger to post a sign or other General Permit coverage notice at a location viewable and legible by the public from a safe, publicly accessible location. This General Permit requires the posting of the project’s unique WDID number, waiver identification number, and site and project contact information. If posting in a publicly accessible location is not possible, the discharger must make the site-specific WDID readily available upon request. 91 The SWPPP must be amended, or a new SWPPP developed by the discharger’s QSD if not already in compliance with this General Permit’s SWPPP requirements in the Order for Linear Underground and Overhead Projects.
92 State Water Resources Control Board, NPDES Storm Water Fees, <https://waterboards.ca.gov/resources/fees/water_quality/#stormwater> [as of May 20, 2021]
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I.M. Notice of Termination Final Stabilization
This General Permit is consistent with the 2022 U.S. EPA NPDES General Permit for Discharges from Construction Activity which requires the following for Notice of Termination final stabilization:

I.M.1. Establish uniform, perennial cover of vegetation93 (i.e., evenly distributed, without large bare areas) to provide 70 percent or more of the cover that is provided by permanent vegetation in local undisturbed areas; and/or I.M.2. Implement permanent non-vegetative stabilization measures to provide effective cover of any areas of exposed soil.

I.M.3. Exceptions:
a. Arid, semi-arid, and drought-stricken areas. Final stabilization is met if the area has been seeded or planted to establish vegetation that provides 70 percent or more of the cover that is provided by permanent vegetation in local undisturbed areas within three years and, to the extent necessary to prevent erosion on the seeded or planted area, non-vegetative erosion controls have been applied that provide cover for at least three years without active maintenance. b. Disturbed areas on agricultural land that are restored to their preconstruction agricultural use.
c. Areas that need to remain disturbed (e.g., racetracks, animal corrals, baseball diamonds, etc.). In limited circumstances, stabilization may not be required if the intended function of a specific area of the site necessitates that it remains disturbed, and only the minimum area needed remains disturbed (e.g., dirt access roads, utility pole pads, areas being used for storage of vehicles, equipment, materials).

I.N. Discharge Prohibitions
This General Permit authorizes the discharge of stormwater to surface waters from construction activities that result in the disturbance of one or more acres of land, provided that the discharger satisfies all General Permit conditions. This General Permit prohibits the discharge of pollutants other than stormwater and non- stormwater discharges authorized by this General Permit or another NPDES permit.

This General Permit also prohibits all discharges which contain a hazardous substance in excess of reportable quantities established in 40 Code of Federal Regulations §§ 117.3 and 302.4, unless a separate NPDES permit has been issued to regulate those discharges. In addition, this General Permit incorporates discharge prohibitions contained in water quality control plans, as implemented by the nine 93 Applications of products where stabilization is dependent on vegetative growth (e.g., hydroseed) does not meet final stabilization criteria if vegetative growth is not achieved.

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Regional Water Boards. Discharges to Areas of Special Biological Significance (ASBS) are prohibited unless covered by an exception that the State Water Board has approved.

Non-stormwater discharges include a wide variety of sources, including improper dumping, spills, or leakage from storage tanks or transfer areas. Non-stormwater discharges may contribute significant pollutant loads to receiving waters. Measures to control spills, leakage, and dumping, and to prevent illicit connections during construction must be addressed through structural as well as non-structural BMPs.

The State Water Board recognizes, however, that certain non-stormwater discharges may be necessary for the completion of construction projects. Authorized non-stormwater discharges may include those from de-chlorinated potable water sources such as: fire hydrant flushing, irrigation of vegetative erosion control measures, pipe flushing and testing, water to control dust, uncontaminated ground water dewatering, and other discharges not subject to a separate general NPDES permit adopted by a region. Therefore, this General Permit authorizes such discharges provided they meet the following conditions:

These authorized non-stormwater discharges must:

1. Comply with BMPs as described in the SWPPP;

2. Filter or treat, using appropriate technology, all dewatering discharges from sedimentation basins;

3. Meet the numeric action levels for pH and turbidity; and

4. Not cause or contribute to a violation of water quality standards.

Additionally, authorized non-stormwater discharges must not be used to clean up failed or inadequate construction or post-construction BMPs designed to keep materials on-site. This General Permit prohibits the discharge of stormwater that causes or threatens to cause pollution or nuisance. Dewatering is also discussed in Section I.B.3.b.iii above.

I.O. Technology and Water Quality Based Effluent Limitations for All Types of Discharges
I.O.1. Technology-Based Effluent Limitations
NPDES permits for stormwater discharges associated with construction activity must meet all applicable provisions of §§ 301 and 402 of the Clean Water Act.

These provisions require controls of pollutant discharges that utilize best available technology economically achievable (BAT) for toxic pollutants and non- conventional pollutants and best conventional pollutant control technology (BCT) for conventional pollutants. Additionally, these provisions require controls of pollutant discharges to reduce pollutants and any more stringent controls necessary to meet water quality standards. The U.S. EPA has already established such limitations, known as effluent limitation guidelines, for some industrial ORDER WQ 2022-0057-DWQ
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categories. The State Water Board implemented the effluent limitation guidelines and standards for the construction and development point source category into this General Permit as discussed in Section I.B.3 above. In instances where there are no effluent limitation guidelines, the permit writer is to use best professional judgment to establish discharger requirements using BAT and BCT technology.

This General Permit contains narrative effluent limitations, technology-based numeric effluent limitations for active treatment systems and BMP-based, narrative, and numeric water quality-based effluent limitations for Total Maximum Daily Loads (TMDL) waste load allocation implementation.

The previous permit, as originally adopted by the State Water Board on September 2, 2009, contained numeric effluent limitations for pH (within the range of 6.0 and

9.0 pH units) and turbidity (500 Nephelometric Turbidity Units (NTU)) that applied only to Risk Level 3 and linear underground and overhead project Type 3 construction sites. The California Building Industry Association, the Building Industry Legal Defense Foundation, and the California Business Properties Association (petitioners) challenged the previous permit in California Building Industry Association et al. v. State Water Resources Control Board. The Superior Court ruled in favor of the State Water Board on almost all of the issues the petitioners raised, but the Superior Court invalidated the numeric effluent limitations for pH and turbidity for Risk Level 3 and linear underground and overhead project Type 3 sites because it determined that the State Water Board did not have sufficient BMP performance data to support those numeric effluent limitations. As a result of the Superior Court’s writ of mandamus, the numeric effluent limitations for pH and turbidity were removed from the previous permit, except for active treatment systems. In addition, the previous permit required Risk Level 3 and linear underground and overhead project Type 3 dischargers with discharges directly to surface waters to conduct receiving water monitoring if directed by Water Boards whenever their effluent exceeds specified receiving water monitoring triggers. The receiving water monitoring triggers were established at the same levels as the previous numeric effluent limitations (effluent pH outside the range of 6.0 and 9.0 pH units or turbidity exceeding 500 NTU). In restoring the receiving water monitoring requirements, the State Water Board determined that it was appropriate to require receiving water monitoring at the request of the Water Boards for these types of sites with discharges directly to surface waters that exceeded the receiving water monitoring triggers under any precipitation event scenarios because these sites represent the highest threat to receiving water quality.

This General Permit includes receiving water monitoring requirements for Risk Level 3 and linear underground and overhead project Type 3 with discharges directly to surface water. An exceedance of a receiving water monitoring trigger is not a violation of this General Permit.

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BAT and BCT technologies include passive systems such as conventional runoff and sediment control and treatment systems such as coagulation or flocculation using sand filtration, when appropriate. Such technologies allow for effective treatment of soil particles less 0.02 mm (medium silt) in diameter. This General Permit requires the discharger to install structural controls, as necessary, such as erosion and sediment controls that meet BAT and BCT to achieve compliance with water quality standards. These effluent limitations constitute compliance with the requirements of the Clean Water Act.

Because this General Permit is an NPDES permit, there is no legal requirement to address the factors set forth in Water Code §§ 13241 and 13263, unless the permit is more stringent than what federal law requires. (See City of Burbank v. State Water Resources Control Bd. (2005) 35 Cal.4th 613, 618, 627.) None of the requirements in this General Permit are more stringent than the minimum federal requirements, which include technology-based requirements achieving BAT and BCT and strict compliance with water quality standards. The inclusion of numeric effluent limitations in the permit for active treatment systems does not cause this General Permit to be more stringent than current federal law. Numeric effluent limitations and best management practices are simply two different methods of achieving the same federal requirement: strict compliance with state water quality standards. Federal law authorizes both narrative and numeric effluent limitations to meet state water quality standards. The use of numeric effluent limitations to achieve compliance with water quality standards is not a more stringent requirement than the use of BMPs. (State Water Board Order No. WQ 2006-0012 (Boeing).) Accordingly, the State Water Board does not need to take into account the factors in Water Code §§ 13241 and 13263.

The State Water Board has concluded that the establishment of BAT and BCT will not create or aggravate other environmental problems through increases in air pollution, solid waste generation, or energy consumption. While there may be a slight increase in non-water quality impacts due to the implementation of additional monitoring or the construction of additional BMPs, these impacts will be negligible in comparison with the construction activities taking place on-site and would be justified by the water quality benefits associated with compliance. a. pH Receiving Water Monitoring Trigger
The minimum standard control methods for pH in runoff requires the use of preventive measures such as avoiding concrete pours during rainy weather, covering concrete and directing flow away from fresh concrete if a pour occurs during rain, covering scrap drywall and stucco materials when stored outside and potentially exposed to rain, and other housekeeping measures to control potential contaminants. If necessary, pH-impaired stormwater from construction sites can be treated in a filter, settling pond, or basin, with additional natural or chemical treatment required to meet pH limits set forth in this General Permit.

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The basin or pond acts as a collection point and holds stormwater for a sufficient period for the contaminants to be settled out, either naturally or artificially, and allows any additional treatment to take place. The State Water Board considers these techniques to be equivalent to BCT. The State Water Board used best professional judgement in determining the pH concentration discharge limitations.

The chosen trigger was established by calculating three standard deviations above and below the mean pH of runoff from highway construction sites94 in California. Proper implementation of BMPs should result in discharges that are within the range of 6.0 to 9.0 pH units.
b. Turbidity Receiving Water Monitoring Trigger
The turbidity receiving water monitoring trigger of 500 NTU is a performance- based trigger and was developed using three different analyses aimed at finding the appropriate threshold to set the performance-based limit to ensure environmental protection, effluent quality, and cost-effectiveness. The analyses fell into three, main types: (1) an ecoregion-specific dataset developed by Simon et. al. (2004); (2) Statewide Regional Water Quality Control Board enforcement data; and (3) published, peer-reviewed studies and reports on in- situ performance of best management practices in terms of erosion and sediment control on active construction sites.

A 1:3 relationship between turbidity (expressed as NTU) and suspended sediment concentration (expressed as mg/L) is assumed based on a review of suspended sediment and turbidity data from three gauges used in the USGS National Water Quality Assessment Program:

USGS 11074000 SANTA ANA R BL PRADO DAM CA
USGS 11447650 SACRAMENTO R A FREEPORT CA
USGS 11303500 SAN JOAQUIN R NR VERNALIS CA
The receiving water monitoring trigger represents staff determination that the trigger value is the most practicable based on available data. The turbidity receiving water monitoring trigger represents a bridge between the narrative effluent limitations and receiving water limitations. State Water Board staff analyzed construction site discharge information (monitoring data, estimates) and receiving water monitoring information to support this receiving water monitoring trigger.
94 California Department of Transportation, Caltrans Construction Sites Runoff Characterization Study (September 2002) <https://dot.ca.gov/-/media/dot- media/programs/environmental-analysis/documents/env/ctsw-rt-03-065-a11y.pdf> [as of May 20, 2021]
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Compliance with this value does not necessarily represent compliance with either the narrative effluent limitations (as enforced through the BAT and BCT standard) or the receiving water limitations since the turbidity receiving water monitoring trigger represents an appropriate threshold level expected at a site.

In the San Diego region, some inland surface waters have a receiving water objective for turbidity equal to 20 NTU. A discharge up to, but not exceeding, the turbidity receiving water monitoring trigger of 500 NTU may still cause or contribute to the exceedance of the 20 NTU standard. Most of the waters of the State are protected by turbidity objectives based on background conditions.

Table 3 – Regional Water Board Basin Plans, Water Quality Objectives for Turbidity
Regional Water
Board WQ Objective Background/Natural
Turbidity
Maximum
Increase
1 Based on background All levels 20 percent
2 Based on background > 50 NTU 10 percent
3 Based on background
0-50 JTU
50-100 JTU
> 100 JTU
20 percent
10 JTU
10 percent
4 Based on background 0-50 NTU
> 50 NTU
20 percent
10 percent
5 Based on background
0-5 NTU
5-50 NTU
50-100 NTU
> 100 NTU
1 NTU
20 percent
10 NTU
10 percent
6 Based on background All levels 10 percent
7 Based on background N/A N/A
8 Based on background
0-50 NTU
50-100 NTU
> 100 NTU
20 percent
10 NTU
10 percent
9 Inland Surface Waters,
20 NTU
All others, based on
background
0-50 NTU
50-100 NTU
> 100 NTU
20 percent
10 NTU
10 percent
Table 4 shows the suspended sediment concentrations at the 1.5-year flow recurrence interval for the 12 ecoregions in California from Simon et. al (2004).

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Table 4 – Results of Ecoregion Analysis
Ecoregion Percent of California Land
Area
Median Suspended Sediment
Concentration (mg/L)
1 9.1 874
4 0.2 120
5 8.8 35.6
6 20.7 1530
7 7.7 122
8 3.0 47.4
9 9.4 284
13 5.2 143
14 21.7 5150
78 8.1 581
80 2.4 199
81 3.7 503
The area-weighted average for the suspended sediment concentration is 1633 mg/L.

If a 1:3 relationship between turbidity and suspended sediment is assumed, the median turbidity is 544 NTU.

The following Table 5 is composed of turbidity readings measured in NTUs from administrative civil liability actions for construction sites from 2003 - 2009.

This data was derived from the complete listing of construction-related administrative civil liabilities (ACLs) for the six-year period. All administrative civil liabilities were reviewed and those that included turbidimeter readings at the point of stormwater discharge were selected for this dataset.

Table 5 – Administrative Civil Liabilities (ACL) Sampling Data taken by Regional Water Board Staff
WDID# Region Discharger Turbidity (NTU)
5S34C331884 5S Bradshaw Interceptor Section
6B 1800
5S05C325110 5S Bridalwood Subdivision 1670
5S48C336297 5S Cheyenne at Browns Valley 1629
5R32C314271 5R Grizzly Ranch Construction 1400
6A090406008 6T El Dorado County Department
of Transportation, Angora Creek 97.4
5S03C346861 5S TML Development, LLC 1600
6A31C325917 6T Northstar Village See Subdata Set
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Table 6 – Subdata Set Turbidity for Point of Stormwater Runoff Discharge at Northstar Village
Date Turbidity (NTU) Location
10/5/2006 900 Middle Martis Creek
11/2/2006 190 Middle Martis Creek
01/04/2007 36 West Fork, West Martis Creek
02/08/2007 180 Middle Martis Creek
02/09/2007 130 Middle Martis Creek
02/09/2007 290 Middle Martis Creek
02/09/2007 100 West Fork, West Martis Creek
02/10/2007 28 Middle Martis Creek
02/10/2007 23 Middle Martis Creek
02/10/2007 32 Middle Martis Creek
02/10/2007 12 Middle Martis Creek
02/10/2007 60 West Fork, West Martis Creek
02/10/2007 34 West Fork, West Martis Creek
A 95 percent confidence interval for mean turbidity in an administrative civil liability order was constructed. The data set used was a small sample size, so the 500 NTU (the value derived as the receiving water monitoring trigger for this General Permit) needed to be verified as a possible population mean. In this case, the population refers to a hypothetical population of turbidity measurements of which our sample of 20 represents. A t-distribution was assumed due to the small sample size:

Mean: 512.23 NTU
Standard Deviation: 686.85
Margin of Error: 31.45
Confide Interval: 190.78 NTU (Low), 833.68 NTU (High)
Based on a constructed 95 percent confidence interval, an administrative civil liability order turbidity measurement will be between 190.78 – 833.68 NTU. 500 NTU falls within this range. Using the same data set, a small-sample hypothesis test was also performed to test if the administrative civil liability turbidity data set contains enough information to cast doubt on choosing a 500 NTU as a mean. 500 NTU was again chosen due to its proposed use as an acceptable value. The test was carried out using a 95 percent confidence interval. Results indicated that the administrative civil liability turbidity data set does not contain significant sample evidence to reject the claim of 500 NTU as an acceptable mean for the administrative civil liability turbidity population.

There are few published, peer-reviewed studies and reports on in-situ performance of best management practices in terms of erosion and sediment control on active construction sites. The most often cited study is a report titled, ORDER WQ 2022-0057-DWQ
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“Improving the Cost Effectiveness of Highway Construction Site Erosion and Pollution Control”95. The primary author, Dr. Horner states the following in a comment letter to the State Water Board summarizing this report:
“The most effective erosion control product was wood fiber mulch applied at two different rates along with a bonding agent and grass seed in sufficient time before the tests to achieve germination. Plots treated in this way reduced influent turbidity by more than 97 percent and discharged effluent exhibiting mean and maximum turbidity values of 21 and 73 NTU, respectively. Some other mulch and blanket materials performed nearly as well. These tests demonstrated the control ability of widely available BMPs over a very broad range of erosion potential.”
Other technologies studied in this report produced effluent quality at or near 100 NTU. It is the best professional judgement of the State Water Board staff that erosion control is preferred and that technology performance in a controlled study showing effluent quality directly leaving a BMP is always easier and cheaper to control than effluent being discharged from the project (edge of property, etc.).

To summarize, the analysis showed that: (1) results of the Simon et. al dataset reveals turbidity values in background receiving water in California’s ecoregions range from 16 NTU to 1716 NTU (with a mean of 544 NTU); (2) based on a constructed 95 percent confidence interval, construction sites will be subject to administrative civil liability (ACL) when their turbidity measurement falls between 190.78 – 833.68 NTU; and (3) sites with highly controlled discharges employing and maintaining good erosion control practices can discharge effluent from the BMP with turbidity values less than 100 NTU. State Water Board staff has determined, using its best professional judgement, that it is most cost effective to set the receiving water monitoring trigger for turbidity at 500 NTU.

I.O.2. Determining Compliance with Effluent Standards
a. Numeric Action Levels
This General Permit contains technology based numeric action levels for pH and turbidity, and requirements for effluent monitoring at all Risk Level 2 and 3, and linear underground and overhead project Type 2 and 3 sites. The numeric action levels are: a pH numeric action level of 6.5 to 8.5, and a turbidity numeric action level of 250 Nephelometric Turbidity Units (NTUs). Additionally, this General Permit sets a turbidity numeric action level for receiving water 95 Horner, Guedry, and Kortenhof, Improving the Cost Effectiveness of Highway Construction Site Erosion and Pollution Control (1990)
<https://wsdot.wa.gov/research/reports/fullreports/200.1.pdf> [as of April 28, 2022] ORDER WQ 2022-0057-DWQ
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monitoring of 500 NTU. Numeric action levels are essentially numeric benchmark values for certain parameters that, if exceeded in effluent sampling, trigger the discharger to take actions.

The primary purpose of numeric action levels is to assist dischargers in evaluating the effectiveness of their on-site measures. Construction sites need to employ many different systems that must work together to achieve compliance with the permit's requirements. The numeric action levels chosen should indicate whether the systems are working as intended. This General Permit requires dischargers with numeric action level exceedances to implement additional, alternative, or improved BMPs and revise their SWPPPs accordingly to either prevent pollutants in stormwater and authorized non- stormwater discharges from being discharged, or to substantially reduce the pollutants to levels consistently below the numeric action levels. An exceedance of a numeric action level does not constitute a violation of this General Permit, however, failure to implement any applicable requirement of this General Permit, or additional BMPs or improved BMPs to adequately prevent future numeric action level exceedances, and/or not reporting any numeric action level exceedance through SMARTS is a violation of this General Permit. Dischargers are required to electronically self-report any discharges that exceed numeric action levels or numeric effluent limitations. Multiple exceedances of a numeric action level or failure to report numeric action level exceedances through SMARTS can be cause for the discharger to implement an active treatment system.

Another purpose of numeric action levels is to provide information regarding construction activities and water quality impacts. This data will provide the Water Boards and the rest of the stormwater community with more information about levels and types of pollutants present in runoff and how effective the dischargers’ BMPs are at reducing pollutants in effluent. The State Water Board also hopes to learn more about the linkage between effluent and receiving water quality. In addition, these requirements will provide information on the mechanisms needed to establish compliance monitoring programs at construction sites in future permit deliberations.
i. pH
The chosen limits were established by calculating one standard deviation above and below the mean pH of runoff from highway construction sites in California. Proper implementation of BMPs should result in discharges that are within the range of 6.5 to 8.5 pH units.

The Caltrans study included 33 highway construction sites throughout California over a period of four years, which included 120 storm events. All of these sites had BMPs in place that would be generally implemented at all types of construction sites in California.

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The Surface Water Ambient Monitoring Program (SWAMP) has a Guidance Compendium for Watershed Monitoring and Assessment. Sections 3.1.4 and 3.1.5 of this Compendium contain guidance for pH and turbidity sampling.96
ii. Turbidity
The State Water Board’s staff used their best professional judgement to develop a numeric action level that can be used as a learning tool to help dischargers improve their site controls, and to provide meaningful information on the effectiveness of stormwater controls. A statewide turbidity numeric action level has been set at 250 NTU.

The Surface Water Ambient Monitoring Program (SWAMP) has a Guidance Compendium for Watershed Monitoring and Assessment. Sections 3.1.4 and 3.1.5 of this Compendium contain guidance for pH and turbidity sampling.

I.O.3. Receiving Water Limitations
Construction activities that cause or contribute to an exceedance of water quality objectives or standards must be addressed. The dynamic nature of construction activity gives the discharger the ability to quickly identify and monitor the source of the exceedances. This is because when stormwater mobilizes sediment, it provides visual cues of erosion, where corrective actions should take place, and how effective they are once implemented.

This General Permit requires that stormwater, dewatering, and authorized non- stormwater discharges eliminate the discharge of pollutants that cause or contribute to an exceedance of any applicable water quality objectives or standards. The sampling and analysis monitoring requirements in this General Permit will help determine whether BMPs installed and maintained are preventing pollutants in discharges from the construction site that may cause or contribute to an exceedance of water quality objectives or standards.

Water quality objectives or standards consist of designated beneficial uses of surface waters and the adoption of ambient criteria necessary to protect those uses. The ambient criteria are termed “water quality objectives” when adopted by the Water Boards. There is a risk that stormwater runoff from construction sites containing pollutants could enter surface waters and cause or contribute to an exceedance of water quality standards. For that reason, dischargers should be aware of the applicable water quality standards in their receiving waters. The best method to ensure compliance with receiving water limitations is to implement 96 A SWAMP Field Methods Course training CD is also available for the public at <www.waterboards.ca.gov/water_issues/programs/swamp/cdrom.html> or please contact [email protected] to request a copy. [as of May 20, 2021] ORDER WQ 2022-0057-DWQ
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BMPs that prevent pollutants from contacting stormwater or leaving the construction site in runoff.

California water quality standards are published in the Basin Plans adopted by each Regional Water Board, the California Toxics Rule (CTR), the National Toxics Rule (NTR), and Statewide Water Board Plans, for example, the California Ocean Plan.

Dischargers can determine the applicable water quality standards by contacting Regional Water Board staff or by consulting one of the following sources. The actual Basin Plans that contain the water quality standards can be viewed at the website of the appropriate Regional Water Board97, the State Water Board site for statewide plans,98 or the U.S. EPA regulations for the NTR and CTR (40 Code of Federal Regulations §§ 131.36-38). Basin Plans and statewide plans are also available by mail from the appropriate Regional Water Board or the State Water Board. The U.S. EPA regulations are available on their website.99 I.O.4. Water Quality Based Effluent Limitations for Construction Stormwater: TMDLs and Waste Load Allocations
This General Permit implements Clean Water Act § 303(d) impaired water body(ies) with Regional Water Board or U.S. EPA adopted TMDLs identifying sources regulated by this General Permit. The TMDLs in Attachment H include the specific waste load allocation for this activity and source. Dischargers are required to comply with any applicable TMDL requirements in this General Permit (see Attachment H and Section I.W of this Fact Sheet for additional TMDL applicability information).

Responsible Dischargers that are assigned TMDL-related numeric action levels or numeric effluent limitations are required to collect samples in accordance with the non-visible sampling requirements in Attachments D and E and compare all analytical results to the applicable numeric action levels or numeric effluent limitations specified in Attachment H of this General Permit.

I.P. Training Qualifications and Requirements
To ensure that the preparation, implementation, and oversight of the SWPPP is sufficient for effective pollution prevention, the Qualified SWPPP Developer and 97 State Water Resources Control Board, RWQCB Directory, <https://www.waterboards.ca.gov/about_us/contact_us/rwqcbs_directory.html> [as of May 20, 2021]
98 State Water Resources Control Board, Plans and Policies, <https://www.waterboards.ca.gov/plans_policies/> [as of May 20, 2021] 99 U.S. EPA Website <https://www.epa.gov/> [as of May 20, 2021] ORDER WQ 2022-0057-DWQ
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Qualified SWPPP Practitioner are responsible for creating, revising, overseeing, and implementing the SWPPP.

I.Q. Sampling, Monitoring, Reporting, and Record Keeping for Linear Underground and Overhead Projects and Traditional Construction Monitoring Requirements I.Q.1. Introduction
This General Permit requires visual monitoring at all sites and effluent water quality monitoring at all Risk Level 2 and 3 and linear underground and overhead project Type 2 and 3 sites (also some Type 1 and Risk Level 1 sites). Receiving water monitoring may be required by the Regional Water Board at some Risk Level 3 and Type 3 sites as described below. All sites are required to submit the sampling results, inspection records, and Annual Reports specified in this General Permit, which contain specific documentation collected over the reporting period.

I.Q.2. Visual
Visual inspections of stormwater discharges, dewatering discharges, authorized non-stormwater discharges, and unauthorized non-stormwater discharges are required for all sites subject to this General Permit. This General Permit requires dischargers to implement corrective actions at the site to address deficiencies identified during the visual monitoring.

All dischargers are required to conduct visual inspections as described in General Permit Attachment’s D or E. This General Permit requires the discharger to visually-inspect a site for indications of pollutants in stormwater runoff, erosion, failed BMPs, and improper BMP installation. Each discharge location and drainage area require an inspection for the presence of (or indications such as erosion, pollutant mobilization, or other potential threat to human health and the environment) unauthorized and authorized non-stormwater discharges and their sources. Dischargers must conduct pre, during, and post-precipitation event inspections to: (1) identify adequacy of BMP design, implementation, and effectiveness, (2) identify any necessary additional BMPs, and (3) revise the SWPPP on-site and in SMARTS accordingly. Dischargers must maintain on-site records of all visual observations, personnel performing the observations, observation dates, weather conditions, locations observed, and corrective actions taken in response to the observations.

This General Permit requires visual monitoring for precipitation events which result in the discharge of water from the site. Sites are encouraged to use size catch basins to retain the first flush of a precipitation event, which is consistent with BAT and BCT. The size of a precipitation event cannot be predicted so an adequate trigger for a pre-precipitation event visual inspection is 50 percent or greater probability of producing precipitation based on the National Weather Service Forecast Office of the National Oceanic and Atmospheric Administration (NOAA).

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General Permit Attachments D and E list the minimum criteria for an inspection checklist. Dischargers may develop their own inspection forms or may use a Water Board-developed form if one is available.

Some visual inspections may be delegated by the QSP to an individual that has received training as described in the discharger’s site personnel roles and responsibilities in this General Permit.

I.Q.3. Non-Visible Pollutant Monitoring
This General Permit requires that all dischargers develop a sampling and analysis strategy for monitoring pollutants that are not visually detectable in stormwater.

Some monitoring may be delegated by the QSP to an individual that has received training as described in the discharger’s site personnel roles and responsibilities in this General Permit. Monitoring for non-visible pollutants is required at any site when the exposure of construction materials occurs and where a potential discharge can cause or contribute to an exceedance of a water quality objective or standard. Pollutants found in materials used in large quantities at construction sites throughout California and exposed throughout the rainy season, such as cement, fly ash, and other recycled materials or by-products of combustion are a significant concern for construction discharges. The water quality standards that apply to these materials will depend on their composition. Some of the more common stormwater pollutants from construction activity are not CTR pollutants. Examples of construction non-visible pollutants100 include, but are not limited to, bacteria and viruses, fertilizers or nutrients, herbicides, greases; lubricants; oils, metals, synthetic chemicals, and pesticides.
a. Bacteria and Viruses
Bacteria and viruses are common stormwater contaminants. Construction site sources include, but are not limited to, animal excrement, waste management, and sanitary facilities. High levels of indicator bacteria in stormwater have led to the closure of beaches, lakes, and rivers to contact recreation such as swimming.
b. Fertilizers and Nutrients
Fertilizers and nutrients are common stormwater contaminants. Construction site sources include, but are not limited to, landscape fertilization, these nutrients can result in excessive vegetation or algae growth in natural water systems or be toxic to aquatic life, resulting in impaired beneficial uses. 100 Section P.1.b adapted from the CASQA Construction BMP Handbook, p. 1-6, 1-7, 1-

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c. Herbicides and Pesticides
Herbicides and pesticides (including fungicides, rodenticides, and insecticides) have been detected repeatedly in stormwater at levels toxic to certain organisms, even when pesticides have been applied in accordance with label instructions. The washing of construction equipment used for noxious weed removal can also spread invasive species101. Construction site sources include, but are not limited to, noxious weed and vegetation management, pest control, and vector control.
d. Greases, Lubricants, Oils
Greases, lubricants, and oils include a wide array of hydrocarbon compounds and other synthetic materials, some of which are toxic to aquatic organisms at low concentrations. Construction site sources include, but are not limited to, equipment spills and leaks from delivery; storage; use, equipment and vehicle drive train; suspension; hydraulic system cleaning and maintenance, material storage, on-site staff parking areas, paving operations, and waste disposal. e. Metals
Metals including, but not limited to, cadmium, copper, chromium, iron, lead, nickel, and zinc are commonly found in stormwater and are of concern because some are toxic to aquatic organisms, can bioaccumulate (accumulate to toxic levels in aquatic animals such as fish), and have the potential to contaminate drinking water supplies. Construction site sources, include but are not limited to, naturally occurring metals associated with earth disturbance, gravel materials, construction materials, equipment maintenance, equipment fluids, paving operations, and welding and fabrication activities. f. Synthetic Chemicals
Synthetic chemicals may be found in stormwater and can be toxic in low concentrations. Construction site sources include, but are not limited to, batteries, construction materials, chemical fire suppression, chemical storage, equipment and vehicle fueling (also related to Section I.Q.3.d above), paving operations, and waste management.

Many of the above sources can result in construction stormwater discharges containing pollutants. For example, high pH can result from improperly maintained treatment systems, cement and gypsum, and wash waters. Salts can also be found 101 Center for Environmental Excellence by AASHTO, Chapter 4 Construction Practices for Environmental Stewardship 4.11 Vegetation Management in Construction (2019) <https://www.epa.gov/sites/default/files/2015-11/documents/25-25-4-_fr.pdf> [as of April 28, 2022]
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in construction site materials, including but not limited to, fertilizers and nutrients, herbicides and pesticides, soil treatments, and surfactants.

Some of these constituents are subject to Statewide Policy, water quality control plans, or Attachment H’s TMDL Water Quality Based Effluent Limitations.

Dischargers are encouraged to discuss these standards with Water Board staff and other stormwater quality professionals.

The most effective way to reduce or minimize the non-visible sampling and analysis requirements is to reduce and manage exposure of construction materials, activities, and equipment to precipitation and/or stormwater runoff.

Materials or activities that are not exposed do not have the potential to enter stormwater runoff, and therefore receiving water sampling is not required.

Preventing contact between stormwater and construction materials, equipment, or materials or preventing the runoff are the most important BMPs at any construction site.

Preventing or eliminating the exposure of pollutants at construction sites is not always possible. Some materials and activities, such as soil amendments or earth moving equipment, are designed to be used in a manner that will result in exposure to stormwater. In these cases, it is important to make sure that these materials and activities are applied and operated according to the manufacturer’s instructions and at a time when pollutants are less likely to be washed away. Other construction materials can be exposed when storage, waste disposal, or the application of the material is done in a manner not protective of water quality.

Representative sampling is required for these situations, unless there is capture and containment of all stormwater that has been exposed. In cases where construction materials may be exposed to stormwater, but the stormwater is contained and is not allowed to run off the site, sampling will only be required when inspections show that the containment failed or is breached, resulting in potential exposure or discharge to receiving waters.

This General Permit requires the discharger to conduct a pollutant source assessment to develop a list of potential pollutants based on a review of site or project potential sources, which will include construction activities, equipment materials, soil amendments, soil treatments, and historic contamination at the site.

The discharger must review existing environmental and real estate documentation to determine the potential pollutants that could be present on the construction site as a result of past land use activities.

Possible reference materials for previously existing pollution and past land uses:
i. Environmental Assessments;
ii. Initial Studies;
iii. Phase 1 Assessments prepared for property transfers; ORDER WQ 2022-0057-DWQ
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iv. Environmental Impact Reports or Environmental Impact Statements prepared under the requirements of the National Environmental Policy Act or the California Environmental Quality Act; and
v. Available soil chemical analysis results.

I.Q.4. Effluent Monitoring
Consistent with 40 Code of Federal Regulations, § 122.44, all linear underground and overhead project Type 2 and 3 and Risk Level 2 and 3 dischargers (also some Type 1 and Risk Level 1 sites) must perform sampling and analysis of effluent discharges to characterize discharges associated with construction activity from the entire area disturbed by the project. Dischargers must collect samples of stored or contained stormwater that is discharged during or subsequent to a precipitation event. Some monitoring may be delegated by the QSP to an individual that has received training as described in the discharger’s site personnel roles and responsibilities in this General Permit.

This General Permit requires stormwater runoff sampling for pH and turbidity for all Risk Level 2, linear underground and overhead project Type 2, Risk Level 3, and linear underground and overhead project Type 3 sites. Sampling is required at all locations where stormwater, dewatering, and/or authorized non-stormwater associated with construction activity is discharged off-site or enters any on-site waters of the United States (e.g., a creek running through a site). Dischargers are required to identify all sampling locations in the SWPPP and site map and sampling is only required when a discharge occurs. Attachments D and E of this General Permit require specific sampling requirements and non-sampling justifications.

This General Permit contains sampling, analysis, and monitoring requirements for pH and turbidity. Sampling of non-visible pollutants identified in the pollutant source assessment is required when the materials or chemicals have the potential to cause or contribute to an exceedance of a water quality standard (e.g., BMP breach, failure, malfunction, or leak or spill observed during a visual inspection).

This General Permit requires that all dischargers maintain a paper or electronic copy of all required records for three years from the date generated or date submitted, whichever is later. These records shall be available at the site until a Notice of Termination is approved by the Regional Water Board. Linear underground and overhead project documents may be retained in a crew member’s vehicle and made available upon request.
a. Traditional Construction Monitoring Requirements
A summary of the monitoring and reporting requirements is found in Table 7 and 8 below. Dischargers are also required to report and retain records in accordance with this General Permit’s Order and Attachment D requirements.

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Table 7 – Required Monitoring Elements for Risk Levels
Risk Level Visual Non-Visible
Pollutants Effluent Receiving Water
Risk Level 1 Required As needed Where
applicable Not required
Risk Level 2 Required As needed pH, turbidity Not required Risk Level 3 Required As needed pH, turbidity
For discharges directly
to surface waters if:
1) pH or turbidity
Receiving Water
Monitoring Trigger
exceeded; and
2) upon Regional Water
Board direction
Table 8 – Stormwater Effluent Monitoring Requirements by Risk Level Level Frequency Effluent Monitoring
Risk Level 1
When non-visible pollutants, identified in the
SWPPP or otherwise known to be on site,
may be discharged due to failure to
implement BMPs, a container spill or leak, or
a BMP breach, failure, or malfunction.

Applicable non-visible
pollutant parameters
Risk Level 2
and 3
When non-visible pollutants, identified in the
SWPPP or otherwise known to be on site,
may be discharged due to failure to
implement BMPs, a container spill or leak, or
a BMP breach, failure, or malfunction.

Applicable non-visible
pollutant parameters
Risk Level 2
and 3
One sample per discharge location per day
of a precipitation event characterizing
discharges associated with construction
activity from the entire project disturbed area.
pH, turbidity, and
applicable non-visible
pollutant parameters
b. Linear Construction Monitoring and Sampling Requirements Attachment E establishes minimum monitoring and reporting requirements for all linear underground and overhead projects and the specific monitoring requirements depending on project complexity and risk to water quality. The monitoring requirements for Type 1 linear underground and overhead project are less than Type 2 and 3 projects because Type 1 projects have a lower potential to impact water quality.

This General Permit requires the discharger to prepare a monitoring program prior to the start of construction and immediately implement the program at the start of construction for linear underground and overhead projects. The monitoring program must be implemented at the appropriate level to protect water quality at all times throughout the life of the project. Dischargers are also ORDER WQ 2022-0057-DWQ
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required to report and retain records in accordance with this General Permit’s Order and Attachment E requirements.

Table 9 – Require Monitoring Elements for Linear Underground and Overhead Project Types
Risk Level Visual Non-Visible
Pollutants Effluent Receiving Water
Type 1 Required As needed Where applicable Not required Type 2 Required As needed pH, turbidity Not required
Type 3 Required As needed pH, turbidity
For discharges
directly to receiving
waters if:
1) pH or turbidity
Receiving Water
Monitoring
Trigger exceed;
and
2) upon Regional
Water Board
direction.
i. Type 1 Linear Underground and Overhead Project Monitoring Requirements This General Permit requires a discharger to conduct daily visual inspections of Type 1 linear underground and overhead projects during site operating hours while construction activities are occurring. Inspections are to be conducted by qualified personnel and can be conducted in conjunction with other daily activities. Inspections are conducted to ensure the BMPs are adequate, maintained, and in place at the end of the construction day.

The required SWPPP revisions (when appropriate) should be based on the results of the daily inspections and reported so the site General Permit implementation is currently reflected. Inspections can be discontinued in non-active construction areas where soil disturbing activities have been completed and final stabilization has been achieved (e.g., trench has been paved, substructures have been installed, and successful final vegetative cover or other stabilization criteria have been met).

A discharger implementing a monitoring program for Type 1 linear underground and overhead projects is required to implement temporary and permanent stabilization BMPs after active construction is completed.

Inspection activities are required until adequate permanent stabilization has been established and will continue in areas where re-vegetation is chosen until minimum vegetative coverage has been established. The required photograph requirements taken during site inspections are for verification of requirements and are submitted through SMARTS.

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This General Permit also includes the minimum criteria required for an inspection checklist. Dischargers may develop their own inspection forms or may contact the Water Board for an inspection form, if one is available. ii. Type 2 and 3 Linear Underground and Overhead Project Monitoring Requirements
This General Permit requires the discharger to conduct daily visual inspections of Type 2 and 3 linear underground and overhead projects during site operating hours when construction activities are occurring.

Inspections are to be conducted by qualified personnel and can be in conjunction with other daily activities.

All Type 2 and 3 linear underground and overhead project dischargers are required to conduct inspections by qualified personnel of the construction site during site operating hours prior to all anticipated precipitation events, during, and after actual precipitation events. The discharger is required to conduct inspections during site operating hours for each 24-hour period during extended precipitation events. Inspections can be discontinued in non-active construction areas where soil disturbing activities have been completed and final stabilization has been achieved (e.g., trench has been paved, substructures installed, and successful vegetative cover or other stabilization criteria have been met).

The goals of these inspections are: (1) to identify areas contributing to a stormwater discharge; (2) to evaluate whether measures to reduce pollutant loadings identified in the SWPPP are adequate, properly installed, and functioning in accordance with the terms of this General Permit; and (3) to determine if additional control practices or corrective maintenance activities are needed. Equipment, materials, and workers must be available for rapid response to failures and emergencies. All corrective BMP maintenance is to be performed as soon as possible, depending upon worker safety.

All dischargers are required to develop and implement a monitoring program for inspecting Type 2 and 3 linear underground and overhead projects that require temporary and permanent stabilization BMPs after active construction is completed. The inspections will be conducted to ensure the BMPs are adequate and maintained and will continue until adequate permanent stabilization has been established in areas where revegetation is chosen until minimum vegetative coverage has been established.

This General Permit also requires a log of inspections conducted before, during, and after the precipitation event(s) be maintained in the SWPPP.

The log will provide the date and time of the inspection and who conducted the inspection. Photographs must be taken during site inspections and submitted through SMARTS.

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This General Permit’s Attachment E lists minimum criteria required for an inspection checklist. Dischargers may develop their own inspection forms or may contact the Water Board for an inspection form, if one is available. iii. Sampling Requirements for all Linear Underground and Overhead Project Types
Linear underground and overhead projects are subject to sampling and analysis requirements for visible pollutants (i.e., sedimentation/siltation, turbidity, pH) and for non-visible pollutants.
1) Sampling for non-visible pollutants is required for Type 1, 2, and 3 linear underground and overhead projects.

Non-visible pollutant monitoring is required for pollutants associated with construction sites and activities that (1) are not visually detectable in stormwater discharges, (2) are known or should be known to occur on the construction site, and (3) could cause or contribute to an exceedance of water quality standard or objectives in the site’s receiving waters.

Sample collection for non-visible pollutants are required only: (1) during a precipitation event when pollutants associated with construction activities may be discharged with stormwater runoff in the event of a BMP breach, failure, malfunction, leak or spill, (2) identified in the discharge and is from construction activities and/or materials, and (3) when the discharger has failed to adequately clean the area of material and pollutants. Failure to implement appropriate BMPs will trigger the same sampling requirements as those required in (1) above, or when the discharger has failed to implement appropriate BMPs prior to the next precipitation event.

It is not anticipated that all linear underground and overhead projects will be required to collect samples for pollutants not visually detected in runoff due to the nature and character of the construction site and activities as previously described in this Fact Sheet. Most linear underground and overhead projects are constructed in urban areas with public access (e.g., existing roadways, road shoulders, parking areas, etc.). This raises a concern regarding the potential contribution of pollutants from vehicle use and/or from normal activities of the public (e.g., vehicle washing, landscape fertilization, pest spraying, etc.) in runoff from the project site. Since the dischargers are not necessarily the landowners of the project area and are not able to control the presence of these pollutants in the stormwater that runs through their projects, it is not the intent of this General Permit to require dischargers to sample for these pollutants unless they are generated specifically from the linear underground and overhead project materials and/or activities. This General Permit does not require the discharger to sample for these ORDER WQ 2022-0057-DWQ
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types of pollutants except where the discharger has on-site materials or activities containing or specifically generating these pollutants and when the conditions described above occur.
2) Regional Water Board-Required Additional Monitoring Requirements The Regional Water Board can require, in writing, additional monitoring requirements in this General Permit under Clean Water Act authority and specific authorities listed in this General Permit’s Order and Attachment E. Additional monitoring requirements include, but are not limited to, requirements specified in an enforcement order, additional sampling parameters, frequency, methods, practices, and/or reporting (for stormwater, dewatering, and/or non-stormwater) based upon site- specific analysis.
3) Receiving Water Monitoring
This General Permit protects the receiving water’s beneficial uses from construction site pollutants. Risk Level 3 and linear underground and overhead project Type 3 site discharges subject to the receiving water monitoring triggers with: (1) receiving water monitoring trigger exceedances defined in this General Permit, (2) discharges are directly into receiving waters, and (3) the discharger is directed to monitor by the Water Boards are required to monitor the upstream and downstream receiving water(s) for turbidity and pH (if applicable). These requirements were modified to make it clear that they do not apply to discharges to an MS4 that later discharges into a surface water.

Table 10 – Receiving Water Monitoring Requirements
Level or Type Receiving Water Monitoring Triggers
Risk Level 1 and Linear
Underground and Overhead
Project Type 1
Not applicable/required
Risk Level 2 and Linear
Underground and Overhead
Project Type 2
Not applicable/required
Risk Level 3 and Linear
Underground and Overhead
Project Type 3
For discharges directly to surface waters if:
1) pH or turbidity Receiving Water Monitoring Trigger
exceeded; and
2) upon Regional Water Board direction.

I.Q.5. Reporting Requirements
a. Reporting Numeric Effluent Limitation Violations (Water Quality Based Corrective Actions or Numeric Effluent Limitation Violation Report) All discharges subject to TMDL-specific numeric effluent limitations requirements must electronically submit all precipitation event sampling results ORDER WQ 2022-0057-DWQ
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to the Water Boards through SMARTS no later than 10 days after receiving the field analysis results or analytical laboratory results. The purpose of the electronic certification and submittal of the Water Quality Based Corrective Actions or Numeric Effluent Limitation Violation Report is to: (1) allow public access to General Permit-required reporting, (2) document the discharger’s compliance actions, and (3) notify the Water Boards of the exceedance so that they can determine whether any follow-up (e.g., inspection, enforcement) is necessary to bring the site into compliance.

Responsible Dischargers with a water quality exceedance are in violation of this General Permit and must additionally submit the Water Quality Based Corrective Actions or Numeric Effluent Limitation Violation Report containing:
· The analytical method(s), reporting unit(s), and method detection limit(s) of each analytical parameter (analytical results that are less than the method detection limit are to be reported as "less than the method detection limit or <MDL");
· The date, place, and time of sampling;
· Any visual observation (inspections);
· Any measurements, including precipitation; and
· A description of the current BMPs associated with the effluent sample that exceeded the numeric effluent limitation and any proposed corrective actions taken.
b. Reporting Numeric Action Level Exceedances (Numeric Action Level Exceedance Report)
All Risk Level 2 and 3 and linear underground and overhead project Type 2 and 3 dischargers must electronically submit all precipitation event sampling results for the pH and turbidity numeric action levels, through SMARTS, no later than 10 days after the conclusion of the precipitation event. All Risk Level 2 and 3 and linear underground and overhead project Type 2 and 3 dischargers must electronically submit all precipitation event sampling results for TMDL-related numeric action levels, through SMARTS, no later than 10 days after receiving the analytical laboratory results. In the event that any effluent sample exceeds an applicable numeric action level, a Regional Water Board or its delegate may request (in writing) that the Risk Level 2 or 3 and linear underground and overhead project Type 2 or 3 dischargers submit and certify a Numeric Action Level Exceedance Report, through SMARTS, within 30 days of receiving the written request.

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In the event that an applicable pH, turbidity or TMDL-specific numeric action level has been exceeded, the required reporting contains:
· The analytical method(s), reporting unit(s), and method detection limit(s) of each analytical parameter (analytical results that are less than the method detection limit are to be reported as "less than the method detection limit or <MDL");
· The date, place, and time of sampling;
· Any visual observation (inspections);
· Any measurements, including precipitation; and
· A description of the current BMPs associated with the effluent sample that exceeded the numeric action level and any proposed corrective actions taken.
c. Analytical Sample Reporting
All dischargers are required to certify and submit analytical monitoring results in SMARTS using the monitoring ad hoc report (a separate ad hoc monitoring report is needed for each precipitation event). Electronically certified and submitted sampling and analysis results are required to include an upload of the original laboratory reports and chain of custody forms. d. Annual Report
All dischargers must prepare and electronically certify and submit an Annual Report no later than September 1st of each year using SMARTS including the specified information described in this General Permit’s Order and any additional necessary site compliance information such as a summary of all corrective actions taken during the reporting period, or the identification of any compliance activities or corrective actions that were not implemented.

I.Q.6. Record Keeping
According to 40 Code of Federal Regulations §§ 122.21(p) and 122.41(j), the discharger is required to retain paper or electronic copies of all records required by this General Permit for a period of at least three years from the date generated or the date submitted to the Water Boards. A discharger must retain records for a period beyond three years if directed by Regional Water Board.

I.R. Risk Determination
A site Risk Level calculation is the estimated potential for sediment transport and risk to the receiving water. This General Permit contains calculation requirements to determine a project’s Risk Level 1, 2 and 3, or a linear underground and overhead projects Type 1, 2, and 3 as described below. Construction industry-accepted sediment erosion models and Water Boards-provided or site-specific receiving water ORDER WQ 2022-0057-DWQ
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risk models are used to determine pre-construction project and post-construction project risks for all the project’s construction phases.

I.R.1. Traditional Construction Projects
a. Overall Risk Determination
There are two major requirements related to site planning and risk determination in this General Permit. The project’s overall risk is broken up into two elements: (1) project sediment risk (the relative amount of sediment that can be discharged, given the project and location details) and (2) receiving water risk (the risk sediment discharges pose to the receiving waters). i. Project Sediment Risk:

The Revised Universal Soil Loss Equation (RUSLE) is used to calculate watershed sediment risk. The RUSLE was originally developed to calculate sheet and rill erosion rate in tons/acre/project duration. It is consistent with the original intent of the RUSLE to not introduce a project size threshold to develop risk categories expressed on tons/project duration.

The Regional Board has the authority to question any aspect of the sediment risk calculation, including the R factor used in determining Watershed Sediment Risk. The RUSLE2 computer program can also be used to calculate the R factor and in many cases yields more accurate values than those generated from the EPA Erosivity Calculator.

Project Sediment Risk is determined by multiplying the R, K, and LS factors from the Revised Universal Soil Loss Equation (RUSLE) to obtain an estimate of project-related bare ground soil loss expressed in tons/acre. The RUSLE equation is as follows:

A = (R)(K)(LS)(C)(P)
Where:

A is the rate of sheet and rill erosion
R is the rainfall-runoff erosivity factor
K is the soil erodibility factor
LS is the length-slope factor
C is the cover factor (erosion controls)
P is the management operations and support practices (sediment controls)
The C and P factors are given values of 1.0 to simulate bare ground conditions.

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There is a map option102 and a manual calculation option for determining soil loss. For the map option, the R factor for the project is calculated using the online calculator.103 To determine soil loss in tons per acre, the discharger multiplies the R factor times the value for K times LS.

For the manual calculation option, the R factor for the project is calculated using the online calculator. The K and LS factors are determined using Attachment D.1.

Soil loss of less than 15 tons/acre is considered low sediment risk.

Soil loss between 15 and 75 tons/acre is medium sediment risk.

Soil loss over 75 tons/acre is considered high sediment risk.

The soil loss values and risk categories were obtained from mean and standard deviation RKLS values from the U.S. EPA EMAP program. High risk is the mean RKLS value plus two standard deviations. Low risk is the mean RKLS value minus two standard deviations
ii. Receiving Water Risk:

Receiving water risk is based on whether a project drains to a water body or watershed that is sediment-sensitive. A sediment-sensitive water body or watershed is either:
· On the most recent 303(d) list for water bodies impaired for sediment; or · Has the beneficial uses of COLD, SPAWN, and MIGRATORY.

A project that meets at least one of the two criteria has a high receiving water risk. A list of sediment-sensitive water bodies is posted on the State Water Board’s website104 and included in Attachment D.1. An interactive map of 303(d) listed water bodies in California is available on the State Board’s website.105
102 The guidance Geographic Information System Risk maps will be provided electronically on the State Water Board’s website prior to the effective date of this General Permit.
103 U.S. EPA, Rainfall Erosivity Factor Calculator for Small Construction Sites, <https://lew.epa.gov/> [as of May 20, 2021]
104 State Water Board, Surface Water Quality Assessment Webpage, <https://www.waterboards.ca.gov/water_issues/programs/water_quality_assessment/ #impaired> [as of May 20, 2021]
105 State Water Board, 303(d) Integrated Report
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b. Effluent Standards
All dischargers are subject to the narrative effluent limitations specified in the General Permit. The narrative effluent limitations require stormwater discharges associated with construction activity to meet all applicable provisions of §§ 301 and 402 of the Clean Water Act. These provisions require controls of pollutant discharges that utilize BAT and BCT to reduce pollutants and any more stringent controls necessary to meet water quality standards.

Risk Level 2 dischargers that pose a medium risk to water quality are subject to numeric action levels for pH and turbidity, which were established based on best professional judgement. Risk Level 3 dischargers that pose a high risk to water quality are subject to numeric action levels for pH and turbidity, which were established based on best professional judgement.
c. Effluent Monitoring
Effluent monitoring is required for Risk Level 2 and 3 and linear underground and overhead project Type 2 and 3 project sites as described in the Order, Attachments D and E. Effluent monitoring results must be certified and submitted electronically through SMARTS.
d. Good Housekeeping
Proper handling and management of construction materials can help minimize threats to water quality. The discharger must consider good housekeeping measures for construction materials, waste management, vehicle storage and maintenance, landscape materials, and potential pollutant sources. Examples include conducting an inventory of products used, implementing proper storage and containment, and properly cleaning all leaks from equipment and vehicles. e. Non-Stormwater Management
This General Permit’s Order defines the specific authorized non-stormwater discharges allowed and necessary prohibitions on other non-stormwater discharges. Non-stormwater discharges directly connected to receiving waters or the storm drain system have the potential to negatively impact water quality.

The discharger must implement measures to control all non-stormwater discharges (e.g., properly washing vehicles or equipment in contained areas, cleaning streets, and minimizing irrigation runoff) during construction, and construction-associated dewatering activities. This General Permit includes specific construction site dewatering provisions designed to eliminate or reduce pollutant impacts on receiving waters from these activities. f. Erosion Control
The best way to minimize the risk associated with erosion and sedimentation during construction is to disturb as little of the land surface as possible by fitting the development to the terrain. Little grading is necessary and erosion potential ORDER WQ 2022-0057-DWQ
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is lower when development is tailored to natural land contours. Other effective erosion control measures include preserving existing vegetation where feasible, limiting disturbance, timing disturbances around reduced precipitation conditions, and stabilizing and re-vegetating disturbed areas as soon as possible after grading or construction activities. Particular attention must be paid to large, mass-graded sites where the potential for soil exposure to the erosive effects of rainfall, snow melt, and wind is great and where there is potential for significant sediment discharge from the site to surface waters.

Temporary soil stabilization can be the single most important factor in reducing construction site erosion. The discharger is required to consider measures such as: covering disturbed areas with mulch, temporary seeding and vegetation, soil stabilizers, non-toxic binders, fiber rolls or blankets, and permanent seeding. These erosion control measures are only examples of what should be considered and do not preclude the use of new or innovative approaches currently available or being developed. Erosion control BMPs should be the primary means of preventing stormwater contamination, and sediment control techniques should be used to capture any soil that becomes eroded.106 Areas that convey stormwater run-off are required to be appropriately armored against in channel erosion. A California licensed professional engineer may need to provide system design and/or calculations to control the erosion in the conveyance of stormwater (drainage channels).
g. Establishing Vegetation
Planting a site may be necessary during the construction phase to establish vegetation prior to termination of the project. Planted vegetation should match surrounding pre-existing native vegetation. It is expected that local climatic conditions, timing, soil types, soil compaction, topography, and nutrients need to be evaluated to ensure seed germination and plant establishment. The employment of healthy soil107 principles may provide additional guidance on vegetative establishment in dry conditions (e.g., in arid and semi-arid climates dischargers should apply seed prior to the application of mulch). Dischargers may consider the advantages and limitations for each project area in regard to seed planting method (direct drilling, broadcasting, and/or hydraulic applications).
106 U.S. EPA, Developing Your Stormwater Pollution Prevention Plan: A Guide for Construction Sites (May 2007),
<https://www3.epa.gov/npdes/pubs/sw_swppp_guide.pdf> [as of May 20, 2021] 107 California Department of Food and Agriculture, Healthy Soils Program Website <https://www.cdfa.ca.gov/oefi/healthysoils/> [as of May 20, 2021] ORDER WQ 2022-0057-DWQ
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h. Sediment Control
Sediment control BMPs should be the secondary means of preventing polluted stormwater discharges. Sediment control techniques recover some of the soil that becomes eroded when erosion control techniques are ineffective. This General Permit requires dischargers to consider perimeter control measures such as installing silt fences or placing straw wattles below slopes. These sediment control measures are only examples of what should be considered and should not preclude new or innovative approaches currently available or being developed.

Additional requirements for the effective implementation of erosion and sediment controls year-round are imposed on Risk Level and Type 2 and 3 dischargers because these sites pose a higher risk to water quality. This General Permit authorizes the Regional Water Boards to require Risk Level 3 and linear underground and overhead project Type 3 dischargers to implement additional site-specific sediment control requirements when the implementation of other erosion or sediment controls are found to be inadequately protecting the receiving waters.

This General Permit requires the use of wildlife friendly BMPs that minimize wildlife entrapment and sets a prohibition on the discharge of trash and debris.

Wildlife entrapment can be minimized by providing the means for wildlife to escape dig sites that are deeper than one meter and storing materials, like netting and tubing, in locations that are inaccessible to wildlife. Dischargers should use biodegradable wattles containing no plastic that can remain on a site when possible. Wattles containing plastic netting (including plastic specified as photo-degradable) become “trash” in the environment and/or a trap for wildlife. These are also considered “construction materials and waste” and must be disposed of properly per this General Permit.
i. Run-on and Runoff Control
Inappropriate management of run-on and runoff can result in excessive physical and chemical impacts to receiving waters from sediment and increased flows. The discharger is required to manage all run-on and runoff from a project site. Examples include installing berms and other temporary run- on and runoff diversions. Dischargers are responsible for commingled run-on (onto the site or within the site) from areas not related to the site’s construction activities and the pollutants contained in the commingled discharge. j. Snow and Ice melt
Construction sites that are affected by snow and ice conditions shall use BMPs to avoid sedimentation migration and erosion from occurring.

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k. Inspection, Maintenance, and Repair
All measures must be periodically inspected, maintained, and repaired to ensure that receiving water quality is protected. Frequent inspections coupled with thorough documentation and timely repair is necessary to ensure that all measures are functioning as intended.

I.R.2. Linear Underground and Overhead Projects
a. Linear Underground and Overhead Risk Determination
Linear underground and overhead projects vary in complexity and water quality concerns based on project type. This General Permit has varying application requirements based on the project’s risk to water quality. Factors that lead to the characterization of the project include location, sediment risk, and receiving water risk.

Linear projects are separated into project types based on the location and complexity of a project area or project segment/section area. Linear underground and overhead projects have been categorized into three project types as follows:
i. Type 1 linear projects are those construction projects where:
1) 70 percent or more of the construction activity occurs on a paved surface and where areas disturbed during construction will be returned to preconstruction conditions or equivalent protection established at the end of the construction activities for the day; or
2) Greater than 30 percent of construction activities occur within the non- paved shoulders or land immediately adjacent to paved surfaces, or where construction occurs on unpaved improved roads, including their shoulders or land immediately adjacent to them where:
a) Areas disturbed during construction will be returned to pre- construction conditions or equivalent protection established at the end of the construction activities for the day to minimize the potential for erosion and sediment deposition; and
b) Areas where established vegetation was disturbed during construction will be stabilized and re-vegetated by the end of project.

When required, adequate temporary stabilization BMPs will be installed and maintained until vegetation is established to meet minimum cover final stabilization requirements established in this General Permit.

Type 1 linear underground and overhead projects typically do not have a high potential to impact stormwater quality because: (1) these construction activities are not typically conducted during precipitation events, (2) these ORDER WQ 2022-0057-DWQ
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projects are normally constructed over a short period of time108, minimizing the duration that pollutants could potentially be exposed to precipitation, and (3) disturbed soils such as those from trench excavation are required to be hauled away, backfilled into the trench, and/or covered (e.g., metal plates, pavement, plastic covers over spoil piles) at the end of the site operating hours for the construction day.

Type 1 linear underground and overhead projects are determined during the risk assessment found in Attachment E.1 to be 1) low sediment risk and low receiving water risk; 2) low sediment risk and medium receiving water risk; and 3) medium sediment risk and low receiving water risk.

This General Permit requires the discharger to ensure a SWPPP is developed by a Qualified SWPPP Developer for these construction activities that is specific to linear underground and overhead project type, location, and characteristics.
ii. Type 2 Linear Underground and Overhead Projects
Type 2 linear underground and overhead projects are determined to have a combination of High, Medium, and Low project sediment risk along with High, Medium, and Low receiving water risk. Type 2 linear underground and overhead projects are typically constructed over a short period of time like Type 1 projects, however, Type 2 projects have a higher potential to impact water quality because they:
1) Typically occur outside urban or developed areas;
2) Have larger areas of soil disturbance that are not closed or restored at the end of the day;
3) May have on-site stockpiles of soil, spoil, and other materials; 4) Cross or occur in close proximity to a wide variety of sensitive resources that may include, but are not limited to, steep topography and/or water bodies; and
5) Have larger areas of disturbed soils that may be exposed for a longer time interval before final stabilization, cleanup, and/or reclamation occurs.

This General Permit requires the discharger to ensure a SWPPP is developed by a Qualified SWPPP Developer and is implemented these site- specific construction activities for the project type, location, and characteristics.
108 Short period of time refers to a project duration of weeks to months, but typically less than one year in duration.

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iii. Type 3 Linear Underground and Overhead Projects
Type 3 linear underground and overhead projects are determined to have a combination of High and Medium project sediment risk along with High and Medium receiving water risk. Similar to Type 2 projects, Type 3 projects have a higher potential to impact water quality because they:
1) Typically occur outside urban and developed areas;
2) Have larger areas of soil disturbance that are not closed or restored at the end of the day;
3) May have on-site stockpiles of soil, spoil, and other materials; 4) Cross or occur in close proximity to a wide variety of sensitive resources that may include, but are not limited to, steep topography and/or water bodies; and
5) Have larger areas of disturbed soils that may be exposed for a longer time interval before final stabilization, cleanup, and/or reclamation occurs.

This General Permit requires the discharger to ensure a SWPPP is developed by a Qualified SWPPP Developer and is implemented these site- specific construction activities for the project type, location, and characteristics.
b. Programmatic Permitting for Linear Underground and Overhead Projects i. Regional Programmatic Permit Coverage:

Regionwide programmatic permit coverage allows a linear underground and overhead project discharger to submit one Notice of Intent for multiple non- contiguous linear underground and overhead projects, if the projects: 1) are located within one Regional Water Board office boundary, 2) are a group of projects of similar scopes with common construction activities, and 3) have the same Legally Responsible Person. Thus, a linear underground and overhead project discharger may be issued a single waste discharge identification number (WDID) for each group of projects (e.g., electrical transmission, gas line transmission, wildfire prevention, etc.) that meet the above criteria.

A linear underground and overhead project discharger opting to obtain regional programmatic permit coverage must submit a common SWPPP with its application that addresses all the construction activities and pollutant sources relevant to the project scope. The linear underground and overhead project discharger must also submit a Linear Construction Activity Notification in SMARTS for each individual project with site-specific information per Attachment E.2, allowing the Regional Water Board to ORDER WQ 2022-0057-DWQ
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enforce individual projects per the requirements in this Order. Each project will share a WDID and will be assigned a WDID extension to identify and track the individual projects. Each individual project is terminated separately through a Linear Construction Termination Notification in SMARTS, pending Regional Water Board staff approval.

Regionwide programmatic permitting was requested by utility stakeholders to improve administrative efficiency related to construction stormwater permitting, in part by training contractors on a common SWPPP that can be implemented on a site-specific basis.
ii. Statewide Programmatic Permit Coverage for Mandated Installation of Broadband Utilities:

Statewide programmatic permit coverage allows a linear underground and overhead project discharger responsible in deploying construction activities to comply with sections 7 – 13 of the Governor’s Executive Order N-73-20, or amendments thereto, to submit one Notice of Intent for multiple non- contiguous linear broadband underground and overhead projects, if the projects:
· Are located throughout two or more Regional Water Board boundaries, · Are a group of projects for broadband utility installation outside of a construction project otherwise regulated by this General Order, and · Have the same Legally Responsible Person.

The discharger will be issued a single waste discharge identification number (WDID) for each group of projects that meet the above criteria.

A linear underground and overhead project discharger opting to obtain statewide programmatic permit coverage must submit:
· A common SWPPP with its application that addresses all the construction activities and pollutant sources relevant to the project scope, and
· Project-specific additional pollution prevention measures to the common SWPPP, as applicable,
A Linear Construction Activity Notification in SMARTS for each individual project with site-specific and project-specific information per Attachment E.2.

Each individual project will share a common WDID and will be assigned a unique WDID extension corresponding to the Regional Water Board ORDER WQ 2022-0057-DWQ
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jurisdiction and the project risk level. The unique project-specific extension number will allow the corresponding Regional Water Board to enforce individual projects per the requirements in this Order specific to the project risk level. Each individual project is terminated separately through the Linear Construction Termination Notification process in SMARTS, and the Notice of Termination process of this General Permit.

Statewide programmatic permitting was requested by the California Department of Transportation, the statewide agency primarily responsible for the construction activity that fully deploys Governor’s Executive Order N-73-20, or amendments thereto, by July 2026. To improve internal project efficiencies to comply with the executive order by July 2026, the Department has reduced its standard design-to-construction procedures from several months to two-to- three weeks. The permit enrollment administrative efficiency provided by statewide programmatic permitting will allow the Department, and other linear project dischargers deploying the executive order, to obtain permit coverage for individual projects, compatible with shortened design-to construction timelines, without submitting repetitive application information for similar projects within different regions.
c. Linear Underground and Overhead Project Effluent Standards All linear underground and overhead projects are subject to the narrative effluent limitations specified in the General Permit. Type 2 and Type 3 projects are subject to technology-based numeric action levels for pH and turbidity. d. Linear Underground and Overhead Project Good Housekeeping Improper use and handling of construction materials could potentially cause a threat to water quality. All linear underground and overhead project dischargers must comply with a minimum set of Good Housekeeping measures specified in Attachment E of this General Permit to ensure proper construction material site management.
e. Linear Underground and Overhead Project Non-Stormwater Management All linear underground and overhead project dischargers must comply with the Non-Stormwater Management measures specified in Attachment E and Order of this General Permit in order to ensure control of all non-stormwater discharges during construction.
f. Linear Underground and Overhead Project Erosion Control This General Permit requires all linear underground and overhead projects dischargers to implement effective wind erosion control measures, and soil cover for inactive areas. Type 3 linear underground and overhead projects ORDER WQ 2022-0057-DWQ
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posing a higher risk to water quality are additionally required to ensure the post- construction soil loss is equivalent to or less than the pre-construction levels. g. Linear Underground and Overhead Project Sediment Control All linear underground and overhead project dischargers must comply with the general Sediment Control measures specified in Attachment E or this General Permit in order to ensure control and containment of all sediment discharges.

Additional requirements for sediment controls are imposed on Type 2 and 3 linear underground and overhead projects due to their higher risk to water quality.
h. Linear Underground and Overhead Projects Run-on and Runoff Control Discharges originating outside of a project’s perimeter and flowing onto the property can adversely affect the quantity and quality of discharges originating from a project site. All linear underground and overhead projects must comply with the run-on and runoff control measures specified in Attachment E of this General Permit in order to ensure proper management of run-on and runoff.

Due to the lower risk of impacting water quality, Type 1 linear underground and overhead projects are not required to implement run-on and runoff controls unless deemed necessary by the discharger. Examples include installing berms and other temporary run-on and runoff diversions. Dischargers are responsible for commingled run-on (onto the site or within the site) from areas not related to the site’s construction activities and the pollutants contained in the commingled discharge.
i. Linear Underground and Overhead Projects Inspection, Maintenance, and Repair
Proper inspection, maintenance, and repair activities are important to ensure the effectiveness of on-site measures to protect receiving water quality. All linear underground and overhead project dischargers are required to comply with the inspection, maintenance, and repair requirements specified in Attachment E of this General Permit in order to ensure that these activities are adequately performed.

I.S. Active Treatment System109 Requirements
I.S.1. General
The requirements in Attachment F only apply when an active treatment system is implemented on a project site. An active treatment system is defined in this General Permit as “a controlled treatment system that employs chemical 109 An active treatment system is a treatment system that employs chemical coagulation, chemical flocculation, or electrocoagulation in order to reduce turbidity caused by fine suspended sediment.

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coagulation, chemical flocculation, or electrocoagulation to aid in the reduction of turbidity caused by fine suspended sediment.”
The active treatment system is designed to treat and reduce the turbidity level of construction stormwater discharges to meet water quality standards and the requirements of this General Permit at the flowrate required in the Active Treatment System Plans. The specified active treatment system flowrate is designed to dewater the basin within 10 hours. Typical equipment and materials may include pumps, manifolds, flocculants, filter bags, sand media filters, and other items designed to remove suspended materials from construction stormwater. The discharger is required to ensure the operators of the active treatment system are adequately trained and the appropriate professional designed the Active Treatment System Plan.

Bonded-fiber matrices, hydromulches, spray tackifiers, and other land-applied products used to stabilize soil are not considered active treatment nor passive treatment, but rather a form of erosion control.

The use of an active treatment system may be necessary when: (1) traditional erosion and sediment controls do not effectively control accelerated erosion at the construction site, (2) the construction site stormwater discharges may cause or contribute to an exceedance of a water quality standard, and/or (3) site constraints (e.g., very steep or long slope lengths,110 clay, highly erosive soils) inhibit the ability to construct a correctly sized sediment basin.

The active treatment system industry in California started in the mid-1990s and is relatively young, however many developers use these systems to treat stormwater discharges from their construction sites. The active treatment system requirements in this General Permit are based on those in place for small wastewater treatment systems, active treatment system regulations from the Central Valley Regional Water Quality Control Board (September 2005 memorandum “2005/2006 Rainy Season – Monitoring Requirements for Stormwater Treatment Systems that Utilize Chemical Additives to Enhance Sedimentation”), the State of Washington’s Department of Ecology Construction Stormwater Program, and recent advances in technology and knowledge of coagulant performance and aquatic safety.

The effective design of an active treatment system requires a detailed survey and analysis of site conditions. Properly planned and implemented active treatment system provide high-quality discharges and prevent significant impacts to surface water quality, even under extreme environmental conditions. 110 Pitt, R., S. Clark, and D. Lake. 2006. Construction Site Erosion and Sediment Controls: Planning, Design, and Performance. DEStech Publications. Lancaster, PA. 370pp.

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These systems can be very effective in reducing the sediment in stormwater runoff, but the systems that use additives or polymers to enhance sedimentation also pose a potential risk to water quality (e.g., inadequate training, operational failure, equipment failure, additive or polymer release). The State Water Board is concerned about the potential acute and chronic impacts that the polymers and other chemical additives may have on fish and aquatic organisms if released in sufficient quantities or concentrations. The literature and anecdotal evidence of polymer releases causing aquatic toxicity in California supports this concern.111 For example, cationic polymers have been shown to bind with the negatively charged gills of fish, resulting in mechanical suffocation.112 This General Permit establishes residual polymer monitoring and toxicity testing requirements due to the potential toxicity impacts associated with the release of additives or polymers into receiving waters from construction sites utilizing an active treatment system.

The primary treatment process in an active treatment system is coagulation and flocculation. Active treatment system operate on the principle that the added coagulant is bound to suspended sediment, forming floc, which is gravitationally settled in tanks or a basin, or removed by sand filters. A typical installation utilizes an injection pump upstream from the clarifier tank, basin, or sand filters, which is electronically metered to both flow rate and suspended solids level of the influent, assuring a constant dose. The coagulant mixes and reacts with the influent, forming a dense floc. The floc may be removed by gravitational setting in a clarifier tank or basin, or by filtration. Water from the clarifier tank, basin, or sand filters may be routed through cartridge(s) and/or bag filters for final polishing. Vendor- specific systems use various methods of dose control, sediment and floc removal, filtration, etc., that are detailed in project-specific documentation. The particular coagulant and/or flocculant used for a given project is determined based on the site water chemistry because the coagulants are specific in their reactions with various types of sediments. Appropriate selection of dosage must be carefully matched to the characteristics of each site. This General Permit prohibits the operation of an active treatment system or the batch storage to cause an uncontrolled release of chemicals used during the flocculation, coagulation, and/or filtration process for suspended sediment particles because these chemicals can negatively affect the beneficial uses of receiving waters and/or degrade water quality (e.g., acute and chronic toxicity).

Active treatment system are operated in two differing modes, batch or flow- through. Batch treatment can be defined as Pump-Treat-Hold-Test-Release. In 111 RomØen, K., B. Thu, and Ø. Evensen. 2002. Immersion delivery of plasmid DNA II. A study of the potentials of chitosan-based delivery system in rainbow trout (Onchorhynchus mykiss) fry. Journal of Controlled Release 85: 215-225. 112 Bullock, G., V. Blazer, S. Tsukuda, and S. Summerfelt. 2000. Toxicity of acidified chitosan for cultured rainbow trout (Oncorhynchus mykiss). Aquaculture 185:273-280.

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batch treatment, water is held in a basin or tank, and is not discharged until treatment is complete. Batch treatment involves holding or recirculating the treated water in a holding basin or tank(s) until treatment is complete or the basin or storage tank(s) is full. In flow-through treatment, water is pumped into the active treatment system directly from the runoff collection system or stormwater holding pond, where it is treated and filtered as it flows through the system and is then directly discharged. “Flow-through treatment” is also referred to as “continuous treatment.”
I.S.2. Active Treatment System Effluent Standards
This General Permit requires discharges of stormwater associated with construction activity that undergo active treatment to comply with special operational and effluent limitations to ensure that these discharges do not adversely affect the beneficial uses of the receiving waters or cause degradation of their water quality and establishes numeric effluent limitations for discharges from construction sites that utilize an active treatment system. An exceedance of the active treatment system numeric effluent limitation constitutes a General Permit violation. These systems lend themselves to technology-based numeric effluent limitations for turbidity and pH because of their known reliable treatment. Advanced systems have been in use in some form since the mid-1990s. An active treatment system is considered reliable, can consistently produce a discharge of less than 10 NTU, and has been used successfully at many sites in several states since 1995 to reduce turbidity to very low levels.

This General Permit contains “compliance storm (precipitation) event” exceptions from the technology-based numeric effluent limitations for active treatment system discharges. The rationale is that technology-based requirements are developed assuming a certain design storm (precipitation) event. The industry-standard active treatment system design storm is 10-year, 24-hour (as stated in Attachment F of this General Permit), so the compliance precipitation event has been established as the 10-year, 24-hour event as well to provide consistency.

I.T. Passive Treatment Requirements
The U.S. EPA’s 2022 NPDES General Permit for Stormwater Discharges from Construction Activities113 requires the regulation of any chemically enhanced stormwater treatment. Chemically enhanced treatments are split into two categories:
active treatment systems and passive treatment technologies (passive treatment including chemical and products). More information regarding active treatment systems can be found in the Section I.S above.
113 U.S. EPA, 2022 NPDES General Permit for Discharges from Construction Activities (January 11, 2017), <https://www.epa.gov/npdes/2022-construction-general-permit- cgp#2022cgp>
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Passive treatment chemicals and products bind fine soil particles together through chemical ionic processes allowing heavy particles to settle out of solution without a fully mechanical or engineered system. Passive treatment technologies in the construction industry typically use coagulants and flocculants such as polyacrylamides (PAMs).

Construction site operators and dischargers regularly use passive treatment to reduce the turbidity levels in construction stormwater runoff. The construction industry uses passive treatment technologies because these products are a cost- effective method of reducing turbidity for compliance with turbidity numeric action levels in this General Permit, especially compared to active treatment systems.

Examples of chemically enhanced BMPs used to meet General Permit turbidity numeric action levels are blocks, wattles, or water-applied products.

Many other industries use passive treatment chemicals in water purification, food production, and other industrial applications to reduce the turbidity and concentration of other pollutants in the discharge.

The types of flocculants and coagulants that can be included in passive treatment for this General Permit are non-ionic and anionic flocculants and coagulants. Cationic flocculants and coagulants can be used in an active treatment system and are regulated in Attachment F. Research on applicable chemical information indicates that many commonly used flocculants are toxic or contain toxic components, and when discharged to surface water have the potential to impact aquatic life and other beneficial uses.

Many types of passive treatment chemicals are toxic to fish and other aquatic organisms. Cationic PAM-based flocculants are acutely toxic to aquatic species in small quantities and are neurotoxins. Other flocculant products such as anionic PAM-based flocculants are chronically toxic to aquatic species in large quantities.

The California Stormwater Quality Association developed past guidance114 on PAMs used in passive treatment technologies and included specific limitations to the use of soil binders containing PAMs:
1) Do not use PAMs on a slope that flows into a waterbody without passing through a sediment trap, sediment basin, or other sediment controls (e.g., wattles, silt fences, gravel bags);
2) The specific PAM copolymer formulation must be anionic. Cationic PAMs should not be used in any application because of known aquatic toxicity problems. Only the highest drinking water grade PAM certified for compliance with ANSI/NSF Standard 60 for drinking water treatment, should be used for soil applications; 114 CASQA Construction BMP Handbook, 2015.

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3) PAMs designated for erosion and sediment control should be “water soluble” or “linear” or “non-cross linked”; and
4) PAMs should not be used as a stand-alone BMP to protect against water-based erosion. When combined with mulch, its effectiveness increases dramatically.

Additionally, a low-turbidity discharge from a passive treatment chemical application site does not always correspond to low levels of solids in the discharge and/or an improvement in water quality downstream because:
1) Turbidity monitoring solely measures small size solids suspended in the water; turbidity monitoring does not measure particle size, weight, or bed load of sediment from flocculated solids leaving a site; and
2) Passive treatment chemicals discharged either by aerial deposition or through stormwater runoff contributes similar toxicity threats to aquatic life.

This General Permit regulates the use of passive treatment in Attachment G, however, specific technology-based and/or water quality-based numeric effluent limitations have not been implemented in this General Permit for passive treatment chemicals because there is currently no consistent and proven data to determine the level of toxicity and water quality impacts that negatively outweighs the economic benefit associated with the use of passive treatment technologies.

I.U. Post-Construction Requirements
I.U.1. General
Past practices for new and redevelopment construction activities have resulted in modified natural watershed and stream processes. This is caused by altering the terrain, modifying the vegetation and soil characteristics, introducing impervious surfaces such as pavement and buildings, increasing drainage density through pipes and channels, and altering the condition of stream channels through straightening, deepening, and armoring. These changes result in a drainage system where sediment transport capacity is increased, and sediment supply is decreased. A receiving channel’s response is dependent on dominant channel materials and its stage of adjustment. Construction activity can lead to impairment of beneficial uses in two main ways:
a. Stormwater discharges occurring during the actual construction process can negatively affect the chemical, biological, and physical properties of downstream receiving waters. The most likely pollutant is sediment due to the disturbance of the landscape, however pH and other non-visible pollutants are also of great concern; and
b. The finished project may result in significant modification of the site’s long-term response to precipitation after most construction activities are completed at a construction site. New development and redevelopment projects have almost ORDER WQ 2022-0057-DWQ
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always resulted in permanent post-construction water quality impacts because more precipitation ends up as runoff and less precipitation is intercepted, evaporated, and infiltrated.

An effective stormwater management strategy must address the full suite of precipitation events (water quality, channel protection, overbank flood protection, extreme flood protection) (Figure 1).

Figure 1 – Suite of Precipitation Events
The post-construction stormwater performance standards in this General Permit specifically address water quality and channel protection events. Overbank flood protection and extreme flood protection events are traditionally dealt with in local drainage and flood protection ordinances. However, measures in this General Permit to address water quality and channel protection also reduce overbank and extreme flooding impacts. This General Permit aims to match post-construction runoff to pre-construction runoff for the 85th percentile, 24-hour storm event, which reduces the risk of impact to the receiving water’s channel morphology and provides some water quality protection.

Projects are exempt from the post-construction requirements in this General Permit if located within an area subject to post-construction standards of an active Phase I or II MS4 permit with approved post-construction requirements or if they are linear underground and overhead projects.

I.U.2. Water Quality
This General Permit requires dischargers to replicate the pre-project runoff water balance (defined as the amount of rainfall that ends up as runoff) for the smallest storms up to the 85th percentile storm event, or the smallest storm event that generates runoff, whichever is larger. Contemporary stormwater management

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generally routes these flows directly to the drainage system, increasing pollutant loads and potentially causing adverse effects on receiving waters. These smaller water quality events happen much more frequently than larger events and generate much higher pollutant loads on an annual basis. There are other adverse hydrological impacts that result from not designing according to the site’s pre- construction water balance. In Maryland, Klein115 noted that baseflow decreases as the extent of urbanization increases. Ferguson and Suckling116 noted a similar relation in watersheds in Georgia. On Long Island, Spinello and Simmons117 noted substantial decreases in base flow in intensely urbanized watersheds.

This General Permit emphasizes runoff reduction through on-site stormwater reuse, interception, evapotranspiration, and infiltration through non-structural controls and conservation design measures (e.g., downspout disconnection, soil quality preservation/enhancement, interceptor trees). Employing these measures close to the source of runoff generation is the easiest and most cost-effective way to comply with the pre-construction water balance standard. Using low-tech runoff reduction techniques close to the source is consistent with a number of recommendations in the literature.118 In many cases, BMPs implemented close to the source of runoff generation cost less than end-of the pipe measures.119 Dischargers are given the option of using the SMARTS Post-Construction Calculator to calculate the required runoff volume or a watershed process-based, continuous simulation model such as the EPA’s Stormwater Management Model (SWMM) or Hydrologic Simulation Program Fortran. Such methods used by the 115 Klein 1979 as cited in Delaware Department of Natural Resources (DDNR). 2004.

Green Technology: The Delaware Urban Runoff Management Approach. Dover, DE, p. 117.
116 Ferguson and Suckling 1990 as cited Delaware Department of Natural Resources (DDNR). 2004. Green Technology: The Delaware Urban Runoff Management Approach. Dover, DE, p. 117.
117 Center for Watershed Protection (CWP). 2000. The Practice of Watershed Protection: Techniques for protecting our nation’s streams, lakes, rivers, and estuaries. Ellicott City, MD, p. 741.
118 Bay Area Stormwater Management Agencies Association (BASMAA). 1997. Start at the Source: Residential Site Planning and Design Guidance Manual for Stormwater Quality Protection. Palo Alto, CA;
McCuen, R.H. 2003 Smart Growth: hydrologic perspective. Journal of Professional Issues in Engineering Education and Practice. Vol (129), p. 151-154; Moglen, G.E. and S. Kim.2007. Impervious imperviousness-are threshold-based policies a good idea? Journal of the American Planning Association, Vol 73 No.2. p. 161-171.
119 Delaware Department of Natural Resources (DDNR). 2004. Green technology: The Delaware Urban Runoff Management Approach. Dover, DE, p. 117.

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discharger will be reviewed by the Regional Water Board upon Notice of Termination application.

I.U.3. Channel Protection
A basic understanding of fluvial geomorphic concepts is necessary to address channel protection. A dominant paradigm in fluvial geomorphology holds that streams adjust their channel dimensions (width and depth) in response to long- term changes in sediment supply and bank full discharge (1.5 to 2-year recurrence interval). The bank full stage corresponds to the discharge at which channel maintenance is the most effective (the discharge at which the moving sediment, forming or removing bars, forming or changing bends and meanders, and generally doing work that results in the average morphologic characteristics of channels).120 Lane (1955 as cited in Rosgen 1996121) showed the generalized relationship between sediment load, sediment size, stream discharge, and stream slope (Figure 2). A change in any one of these variables sets up a series of mutual adjustments in the companion variables with a resulting direct change in the physical characteristics of the stream channel.

Figure 2 – Schematic of the Lane Relationship122
Stream slope multiplied by stream discharge (the right side of the scale) is essentially an approximation of stream power, a unifying concept in fluvial 120 Dunne, T and L.B. Leopold. 1978. Water in Environmental Planning. San Francisco W.H. Freeman and Company.
121 Rosgen. D.L. 1996. Applied River Morphology. Pagosa Springs. Wildland Hydrology. 122 After Lane (1955) as cited in Rosgen (1996).

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geomorphology (Bledsoe 1999). Urbanization generally increases stream power and affects the resisting forces in a channel (sediment load and sediment size represented on the left side of the scale).

Sediment loads can increase from 2 to 40,000 times over pre-construction levels during construction.123 Most of this sediment is delivered to stream channels during large, episodic rain events.124 This increased sediment load leads to an initial aggradation phase where stream depths may decrease as sediment fills the channel, leading to a decrease in channel capacity and increase in flooding and overbank deposition. A degradation phase initiates after construction is completed.

Schumm et. al (1984) developed a channel evolution model that describes the series of adjustments from initial downcutting, to widening, to establishing new floodplains at lower elevations (Figure 3).

Figure 3 – Channel Changes Associated with Urbanization125 Channel incision (Stage II) and widening (Stages III and to a lesser degree, Stage IV) are due to a number of fundamental changes on the landscape. Connected impervious areas and compaction of pervious surfaces increase the frequency and 123 Goldman S.J., K. Jackson, and T.A. Bursztynsky. 1986. Erosion and Sediment Control Handbook. McGraw Hill. San Francisco.
124 Wolman 1967 as cited in Paul, M.P. and J.L. Meyer. 2001. Streams in the Urban Landscape. Annu. Rev. Ecol. Syst. 32, p. 333-365.
125 After incised Channel Evolution Sequence in Schumm et. al 1984.

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volume of bank full discharges.126 Increased drainage density (miles of stream length per square mile of watershed) also negatively impacts receiving stream channels.127 Increased drainage density and hydraulic efficiency leads to an increase in the frequency and volume of bank full discharges because the time of concentration is shortened. Flows from engineered pipes and channels are also often “sediment starved” and seek to replenish their sediment supply from the channel.

Encroachment of stream channels can also lead to an increase in stream slope, which leads to an increase in stream power. In addition, watershed sediment loads and sediment size (with size generally represented as the median bed and bank particle size, or d50) decrease during urbanization.128 This means that even if pre- and post-development stream power is the same, more erosion will occur in the post-development stage because the smaller particles are less resistant (provided they are non-cohesive).

As shown in Stages II and III, the channel deepens and widens to accommodate the increased stream power129 and decrease in sediment load and sediment size.

Channels may actually narrow as entrained sediment from incision is deposited laterally in the channel. After incised channels begin to migrate laterally (Stage III), bank erosion begins, which leads to general channel widening.130 At this point, a majority of the sediment that leaves a drainage area comes from within the channel, as opposed to the background and construction related hillslope 126 Booth, D.B. and C.R. Jackson. 1997. Urbanization of Aquatic Systems: Degradation Thresholds, Stormwater Detection, and the Limits of Mitigation. Journal of the American Water Resources Association Vol. 33, No. 5, p. 1077-1089. 127 May, C.W. 1998. Cumulative effects of urbanization on small streams in the Puget Sound Lowland ecoregion. Conference proceedings from Puget Sound Research ’98 held March 12, 13 1998 in Seattle, WA;
Santa Clara Valley Urban Runoff Pollution Prevention Program. 2002.

Hydromodification Management Plan Literature Review, p. 80. 128 Finkenbine, J.K., D.S. Atwater, and D.S. Mavinic. 2000. Stream health after urbanization. J. Am. Water Resour. Assoc. 36, p. 1149-60; Pizzuto. J.E. W.S. Hession, and M. McBride. 2000. Comparing gravel-bed rivers in paired urban rural catchments of southeastern Pennsylvania. Geology 28, p. 79-82. 129 Hammer 1973 as cited in Delaware Department of Natural Resources (DDNR). 2004.

Green Technology: The Delaware Urban Runoff Management Approach. Dover, DE, p.117;
Booth, D.B. 1990. Stream Channel Incision Following Drainage Basin Urbanization.

Water Resour. Bull. 26, p. 407-417.
130 Trimble, S.W. 1997. Contribution of Stream Channel Erosion to Sediment Yield from an Urbanizing Watershed. Science: Vol. 278 (21), p. 1442-1444.

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contribution. Stage IV is characterized by more aggradation and localized bank instability. Stage V represents a new quasi-equilibrium channel morphology in balance with the new flow and sediment supply regime. In other words, stream power is in balance with sediment load and sediment size.

The magnitude of the channel morphology changes discussed above varies along a stream network as well as with the age of development, slope, geology (sand- bedded channels may cycle through the evolution sequence in a matter of decades whereas clay-dominated channels may take much longer), watershed sediment load and size, type of urbanization, and land use history. It is also dependent on a channel’s stage in the channel evolution sequence when urbanization occurs.

Management strategies must take into account a channel’s stage of adjustment and account for future changes in the evolution of channel form (Stein and Zaleski 2005).131
Traditional structural water quality BMPs (e.g., detention basins and other devices used to store volumes of runoff) unless they are highly engineered to provide adequate flow duration control, do not adequately protect receiving waters from accelerated channel bed and bank erosion, do not address post-development increases in runoff volume, and do not mitigate the decline in benthic macroinvertebrate communities in the receiving waters,132 and suggest that structural BMPs are not as effective in protecting aquatic communities as a continuous riparian buffer of native vegetation. This is supported by the findings of Zucker and White,133 where instream biological metrics were correlated with the extent of forested buffers.

This General Permit requires dischargers to maintain pre-development drainage densities and times of concentration in order to protect channels and encourages dischargers to implement setbacks to reduce channel slope and velocity changes that can lead to aquatic habitat degradation.

There are a number of other approaches for modeling fluvial systems, including statistical and physical models and simpler stream power models.134 The use of 131 Stein, E.S. and S. Zaleski. 2005. Managing runoff to protect natural stream: the latest developments on investigation and management of hydromodification in California.

Southern California Coastal Water Research Project Technical Report 475, p. 26. 132 Horner, R.R. 2006. Investigation of the Feasibility and Benefits of Low-Impact Site Design Practices (LID) for the San Diego Region.
133 Delaware Department of Natural Resources (DDNR). 2004. Green Technology: The Delaware Urban Runoff Management Approach. Dover, DE, p. 117. 134 Finlayson, D.P. and D.R. Montgomery. 2003. Modeling large-scale fluvial erosion in geographic information systems. Geomorphology (53), p.147-164.

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these models in California is described in Stein and Zaleski (2005).135 Rather than require a specific one-size-fits-all modeling method in this permit, the State Water Board intends to develop a stream power and channel evolution model-based framework to assess channels and develop a hierarchy of suitable analysis methods and management strategies. In time, this framework may become a State Water Board water quality control policy.

I.U.4. General Permit Linkage to Overbank and Extreme Flood Protection Site design BMPs (e.g., rooftop and impervious disconnection, vegetated swales, setbacks and buffers) filter and settle out pollutants and provide for more infiltration than is possible for traditional centralized structural BMPs placed at the site’s lowest point. They provide source control for runoff and lead to a reduction in pollutant loads. When implemented, they also help reduce the magnitude and volume of larger, less frequent storm events (e.g., 10-yr, 24-hour storm and larger), thereby reducing the need for expensive flood control infrastructure. Non-structural BMPs can also be a landscape amenity, instead of a large, isolated structure requiring substantial area for ancillary access, buffering, screening, and maintenance facilities. The multiple benefits of using non-structural benefits will be critically important as the state’s population increases and imposes strains upon our existing water resources.

Maintaining predevelopment drainage densities and times of concentration will help reduce post-development peak flows and volumes in areas not covered under a municipal permit. The most effective way to preserve drainage areas and maximize time of concentration is to implement landform grading, incorporate site design BMPs and implement distributed structural BMPs (e.g., bioretention cells, rain gardens, rain cisterns).

This General Permit requires dischargers to maximize sheet flow and use an “open” drainage system (e.g., swales, ditches, vegetated channels) for concentrated flows to meet the drainage density requirement. Sheet flow areas, swales, ditches, and vegetated channels are not considered streams for the purpose of calculating drainage density.

This General Permit requires dischargers to use recommended methods in the applicable local hydraulic design or flood control manual to meet the time of concentration requirements. The discharger is required to use the time of concentration calculation method contained in the Natural Resources Conservation Service’s Technical Release 55: Urban Hydrology for Small Watersheds if a recommended method does not exist.
135 Stein, E.S. and S. Zaleski. 2005. Managing runoff to protect natural stream: the latest developments on investigation and management of hydromodification in California.

Southern California Coastal Water Research Project Technical Report 475, p. 26.

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Dischargers with active General Permit coverage are required to use the post- construction calculator in SMARTS or the approved post-construction standards of an applicable Phase I or Phase II Municipal Separate Storm Sewer System (MS4) NPDES permit to report compliance with this General Permit post-construction requirements.

This General Permit requires the discharger to utilize the post-construction calculator in SMARTS if: (1) a construction project (other than a linear and underground and overhead project that is not subject to this General Permit’s post- construction requirements) was or is approved by the local municipality prior to the municipality having post-construction standards adopted pursuant to a Phase I or Phase II MS4 permit or (2) the project was not subject to the post-construction standards of a Phase I or Phase II entity.

I.V. Stormwater Pollution Prevention Plans (SWPPPs)
U.S. EPA’s Construction General Permit requires that qualified personnel conduct inspections and defines qualified personnel as “a person knowledgeable in the principles and practice of erosion and sediment controls who possesses the skills to assess conditions at the construction site that could impact stormwater quality and to assess the effectiveness of any sediment and erosion control measures selected to control the quality of stormwater discharges from the construction activity.”136 U.S.

EPA also suggests that qualified personnel prepare SWPPPs and points to numerous states that require certified professionals to be on construction sites at all times.

This General Permit requires that all SWPPPs be site-specific and are written, amended, and certified by a Qualified SWPPP Developer and includes the information needed to demonstrate compliance with all requirements of this General Permit to ensure that water quality is being protected. SWPPP development and updates are required to be based on actual site conditions and maintain continued compliance with requirements of this General Permit. This General Permit also requires the current SWPPP be kept on-site, made available for review, and uploaded through SMARTS.

Although the QSD can change over the life of a project, a QSD, representing the discharger, is expected to make necessary corrections and amendments to the original SWPPP throughout the life of the project to ensure the site’s compliance plan with this General Permit is documented and current. Similarly, a QSP, representing the discharger, must also oversee the implementation of the site- specific BMPs described in the corresponding site-specific SWPPP. 136 U.S. EPA, Developing Your Stormwater Pollution Prevention Plan (May 2017), <https://www3.epa.gov/npdes/pubs/sw_swppp_guide.pdf> [as of May 20, 2021] ORDER WQ 2022-0057-DWQ
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The local municipality cannot enforce General Permit requirements; this is done by the Regional Water Board inspectors. The local municipality is typically responsible for ensuring compliance with local stormwater ordinance which prohibits sediment and other pollutants from entering the MS4, and with a local grading ordinance that typically requires an erosion and sediment control plan (typically a sheet in the construction plan set) for projects with a grading permit. The local municipality may have a condition in their MS4 stormwater permit requiring the agency to check that certain items are included in the SWPPP. This does not constitute approval of the SWPPP, and the review is typically conducted prior to issuing a grading permit.

The previous versions of the General Permit required development and implementation of a SWPPP as the primary compliance mechanism. The SWPPP has three major objectives: (1) to help identify the sources of sediment and other pollutants that affect the quality of stormwater discharges, (2) to describe and ensure the implementation of site-specific BMPs to reduce or eliminate sediment and other pollutants in stormwater and non-stormwater discharges, and (3) to convey a plan to restore erosion protection and site hydrology post-construction. The SWPPP must include site-specific BMPs that address source control, pollutant control, and treatment control.

This General Permit shifts some of the previous measures into specific General Permit requirements, each individually enforceable as a General Permit term. This General Permit emphasizes the use of appropriately selected, correctly installed, and maintained site-specific BMPs. This approach provides the flexibility necessary to establish BMPs that can effectively control sources of pollutants during changing construction activities. These specific requirements also improve both the clarity and the enforceability of the General Permit so that the dischargers understand, and the Water Boards and public can determine whether the discharges comply with this General Permit’s requirements.

The SWPPP must be implemented at the appropriate level to protect water quality at all times throughout all of the construction project phases. The SWPPP must remain on the site during construction activities, commencing with the initial mobilization and ending with the termination of coverage under the General Permit. Linear underground and overhead project dischargers are required to make the SWPPP available at the construction site during site operating hours while construction is occurring and shall be made available upon request by a State, Federal, or Municipal inspector. A site-specific SWPPP may be kept in electronic format. All maps and figures must be printed, hard copy, full size, and available on the construction site. Current copies of the BMPs and maps and drawings will be left with the field crew and the original SWPPP shall be made available via a request by radio or telephone when the original SWPPP is retained by a crewmember in a construction vehicle and is not currently at the construction site. The SWPPP shall be available from the SWPPP contact listed in the Permit Registration Documents until stabilization is achieved even when construction activities are complete.

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A SWPPP must be appropriate for the type and complexity of a project and will be developed and implemented to address site-specific conditions. Some projects may have similarities or complexities, yet each project is unique in its progressive state that requires specific description and selection of BMPs needed to address all possible generated pollutants.

I.W. Total Maximum Daily Loads (TMDLs)
I.W.1. Introduction
Total Maximum Daily Loads (TMDLs) are regulatory tools that provide the maximum amount of a pollutant from potential sources in the watershed that a water body can receive while attaining water quality standards. A TMDL is defined as the sum of the allowable loads of a single pollutant from all contributing point sources (waste load allocations) and non-point sources (load allocations), plus the contribution from background sources. (40 Code of Federal Regulations § 130.2, subd. (i).) Discharges covered by this General Permit are considered to be point source discharges, and therefore must comply with effluent limitations that are “consistent with the assumptions and requirements of any available waste load allocation for the discharge prepared by the State and approved by EPA pursuant to 40 Code of Federal Regulations section 130.7.” (40 Code of Federal Regulations § 122.44, subd. (d)(1)(vii).) In addition, Water Code § 13263, subdivision (a), requires that waste discharge requirements implement relevant water quality control plans. Many TMDLs in existing water quality control plans include both waste load allocation and implementation requirements. Attachment H of this General Permit lists the watersheds with U.S. EPA-approved and U.S. EPA- established TMDLs that include TMDL requirements for dischargers covered by this General Permit.

TMDLs are adopted through a separate U.S. EPA and Regional Water Board public process. The previous permit included a list of potentially applicable TMDLs, and this list has been refined in this General Permit through consultation with the Regional Water Boards.

I.W.2. General Permit Implementation Requirements
Water Board staff evaluated and developed the following information in the development of the Attachment H implementation requirements:
· TMDL-specific requirements including implementation timelines, additional monitoring and reporting requirements, compliance determination language regarding compliance with numeric action levels, applicable TMDL-specific effluent limitations, and reporting requirements consistent with the applicable TMDL(s);
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· Information regarding this General Permit’s TMDL-specific requirements, timelines, and deliverables consistent with the assumptions and requirements of applicable waste load allocation(s) to implement the TMDL(s); · Information regarding the implementation of BMPs (as applicable) to comply with applicable waste load allocations;
· Concentration-based monitoring requirements and information regarding the required determination of compliance for numeric effluent limitations through concentration-based compliance monitoring, corresponding calculation methodology, and reporting; and
· Compliance deadlines, based on TMDL implementation schedules, were set for Responsible Dischargers to comply with the TMDL-specific requirements on, and after, the provided date. TMDLs that lacked or surpassed the implementation schedules prior to this issuance of this General Permit were assigned compliance deadlines set for the effective date of this General Permit.

I.W.3. TMDL Evaluation Steps
The State Water Board used the following process to evaluate and translate each TMDL in Attachment H:
· Step 1: Determined whether the TMDL applies to construction stormwater discharges and authorized non-stormwater discharges regulated by this General Permit (discharges regulated by this General Permit); · Step 2: Identified the specific TMDL requirements that are applicable to discharges regulated by this General Permit;
· Step 3: Translated the TMDL requirements into TMDL-specific General Permit requirements, numeric action levels, or numeric effluent limitations; · Step 4: Determined a compliance schedule that corresponds with the compliance date of the TMDL;
· Step 5: Developed monitoring and reporting requirements to determine compliance with waste load allocations;
· Step 6: Identified the existing General Permit requirements applicable to each constituent identified in the TMDLs, and evaluated if additional TMDL-specific requirements were required to implement the TMDL for discharges regulated by this General Permit; and
· Step 7: Provided explanation regarding how the State Water Board translated each TMDL into specific requirements.

I.W.4. Applicability
Responsible Dischargers are: (1) dischargers with Notice of Intent coverage under this General Permit who discharge stormwater associated with construction ORDER WQ 2022-0057-DWQ
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activities and authorized-non-stormwater discharges, (2) either directly or through a municipal separate storm sewer system (MS4) to impaired water bodies identified in a U.S. EPA approved TMDL with an assigned waste load allocation to construction stormwater sources listed in Attachment H, and (3) have identified one or more TMDL-pollutants in the site’s construction stormwater discharges.

Responsible Dischargers must comply with applicable TMDL-specific General Permit requirements in Attachment H and all other applicable provisions of this General Permit.

Each TMDL-specific permit requirement listed in Attachment H (Table H-2 for TMDL-specific General Permit Requirements) provides the specific translation and required actions for Responsible Dischargers as discussed below. Table H-2 includes the specific watershed, water body, or water bodies and additional tributaries to ensure Responsible Dischargers know which Table H-2 TMDL requirement applies depending on the receiving water body(ies) of the site.

This General Permit’s pH and turbidity numeric action levels continue to apply in addition to the TMDL-specific requirements in Table H-2. The measurement of compliance with the TMDL-specific requirements, whether TMDL-related numeric action levels or numeric effluent limits, is defined in the Glossary (Attachment B).

Stormwater discharges are intermittent in nature and many of the Attachment H TMDL waste load allocations are translated to numeric action levels or numeric effluent limitations for protection against acute impacts to beneficial uses in the receiving waters.

The following are examples to assist Responsible Dischargers in determining which water bodies are subject to the TMDLs in Table H-2:
· Watershed example: If the “Impaired Water Body/Watershed” column states “Napa River Watershed,” the TMDL and its requirements are applicable to dischargers discharging directly or through an MS4 into water bodies within the Napa River Watershed.
· River and tributaries (Watershed) example: If the “Impaired Water Body/ Watershed” column states “Los Angeles River and Tributaries,” this TMDL and its requirements are applicable to the dischargers discharging directly or through an MS4 into the Los Angeles River watershed.
· Lagoon example: If the “Impaired Water Body/ Watershed” column states “Colorado Lagoon,” this TMDL and its requirements are applicable to dischargers discharging directly or through an MS4 into the Colorado Lagoon.

TMDL-specific General Permit requirements do not apply to dischargers with a waiver or dischargers that meet the Notice of Non-Applicability (NONA) criteria.

There are currently few environmental laboratory accredited program (ELAP)- accredited laboratories capable of analyzing the following compounds (e.g., ORDER WQ 2022-0057-DWQ
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chlordane, dieldrin, total PCBs, total DDTs, 4,4-DDT, PAHs) to the low concentrations for some of the numeric action levels or numeric effluent limitations in Attachment H. Attachment H, Section I.G.5 provides a modified compliance protocol for Responsible Dischargers for the Los Angeles Area Lakes TMDL that are required to comply with TMDL-related numeric effluent limitations for Chlordane, Dieldrin, DDT, and PCBs. It is the expectation that the Water Boards will provide guidance and alternative methods for a Responsible Discharger to demonstrate compliance, if the Responsible Discharger has provided the Water Boards adequate information demonstrating that:
· It is infeasible to analyze a translated waste load allocation using an ELAP- accredited laboratory;
· The sample results would invalidate federally-required sufficiently sensitive methods; or
· No method in 40 Code of Federal Regulations Part 136 can detect and quantify the amount specified for the construction stormwater.

I.W.5. General Permit Summary
The following requirements, applicable to dischargers enrolled under this General Permit, were considered in determining the necessity of additional TMDL-specific permit implementation for applicable to Responsible Dischargers:
· Storm Water Pollution Prevention Plan (SWPPP): This General Permit requires dischargers to identify construction materials handled at the site and describe all potential sources of pollutants that could be discharged from their site and describe the BMPs that will be implemented to control their discharges. This General Permit requires Responsible Dischargers to revise their SWPPP whenever a significant change in monitoring or sampling occurs. · Non-Stormwater Discharges (NSWDs): The only NSWDs authorized by this General Permit are described in the Order, and the discharge is prohibited unless regulated by a separate NPDES permit.
· Visual Observations: Dischargers are required to conduct pre, during, and post precipitation event site visual inspections which include: 1) monitoring of authorized NSWDs, 2) identification and elimination of unauthorized NSWDs, 3) identification of potential construction pollutant sources, and 4) necessary BMP maintenance and implementation.
· Sampling and Analysis: Dischargers must sample for all construction pollutants (with the potential to discharge to a waters of the United States) identified in their SWPPP in accordance with this General Permit. Dischargers are required to collect and analyze stormwater samples from construction site discharge locations over the reporting period in accordance with the requirements of this General Permit. When this previous permit’s requirements were not sufficient to ORDER WQ 2022-0057-DWQ
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implement the TMDL, additional monitoring and sampling requirements are set forth in Attachment H’s TMDL Compliance Table (Table H-2).

I.W.6. TMDL-Specific Requirements
Attachment H, Table H-2 contains TMDL-specific requirements for each TMDL with sources from discharges regulated by this General Permit. This Fact Sheet discusses TMDLs by pollutant since many of the TMDLs with the same pollutants are translated in the same manner. Table H-2 is organized by Regional Water Board jurisdiction and watershed, allowing the Responsible Dischargers to easily identify their applicable requirements.
a. Bacteria TMDLs
Nine Indicator Bacteria TMDLs (eight established by the Los Angeles Regional Water Quality Control Board and one by the U.S. EPA) apply to construction stormwater dischargers. Each TMDL addresses bacterial pollutants by establishing bacteria water quality objectives for one or more of the following Indicator Bacteria: Enterococcus, Escherichia coli (E. Coli), Fecal Coliform, and Total Coliform. These pollutants are referred to as Indicator Bacteria for the purpose of Attachment H and this Fact Sheet.

The water quality objectives for Indicator Bacteria are specific to fresh and marine waters and designated beneficial uses such as water contact recreation (REC-1), limited water contact recreation (LREC-1), and water non-contact recreation (REC-2).

Recreating in waters exceeding indicator bacteria water quality objectives has long been associated with adverse human health effects. Specifically, local and national epidemiological studies demonstrate that there is a causal relationship between adverse health effects and recreational water quality, as measured by bacterial indicator densities.137
The Indicator Bacteria TMDLs and their beneficial uses are summarized below:
· Ballona Creek, Ballona Estuary, and Sepulveda Channel Bacteria TMDL138:

Fresh Waters (LREC-1, REC-1, REC-2) and Marine Waters (REC-1) 137 Ballona Creek, Estuary, and Tributary Bacteria TMDL, p. 2. 138 Los Angeles Regional Water Board, Ballona Creek, Estuary, and Tributary Bacteria TMDL (June 7, 2012),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R12- 008_RB_BPA.pdf> [as of May 20, 2021]
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· Harbor Beaches of Ventura County Bacteria TMDL139: Marine Waters (REC- 1)
· Long Beach City Beaches and Los Angeles River Estuary Bacteria TMDL140: Marine Waters (REC-1)
· Los Angeles Harbor Bacteria TMDL141: Marine Waters (REC-1) · Los Angeles River Bacteria TMDL142: Fresh Waters (LREC-1) · Malibu Creek Bacteria TMDL143: Fresh Waters (REC-1) and Marine Waters (REC-1)
· Marina del Rey Bacteria TMDL144: Marine Waters (REC-1) 139 Los Angeles Regional Water Quality Control Board, Harbor Beaches of Ventura County (Kiddie Beach and Hobie Beach) Bacteria TMDL (November 1, 2007), <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2007- 017_RB_BPA.pdf> [as of May 20, 2021]
140 United States Environmental Protection Agency IX, Long Beach City Beaches and Los Angeles River Estuary Total Maximum Daily Loads for Indicator Bacteria (March 26, 2012),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Longbeach/finalTMDLs-LongBeachCityBeaches-LARiverEstuaryBacteria.pdf> [as of April 28, 2022]
141 Los Angeles Regional Water Quality Control Board, Los Angeles Harbor Bacteria TMDL (Inner Cabrillo Beach Main Ship Channel) (July 1, 2004), <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2004- 011_RB_BPA.pdf> [as of May 20, 2021] (Los Angeles Harbor Bacteria TMDL) 142 Los Angeles Regional Water Quality Control Board, Los Angeles River Watershed Bacteria TMDL (July 9, 2010),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R10- 007_RB_BPA1.pdf> [as of May 20, 2021] (Los Angeles Bacteria TMDL) 143 Los Angeles Regional Water Quality Control Board, Malibu Creek and Lagoon Bacteria TMDL (June 7, 2012),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R12- 009_RB_BPA.pdf> [as of May 20, 2021] (Malibu Creek Bacteria TMDL) 144 Los Angeles Regional Water Quality Control Board, Marina del Rey Harbor Mother’s Beach and Back Basins Bacteria TMDL (August 7, 2003),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2003- 012_RB_BPA.pdf> [as of May 20, 2021] (Marina del Rey Bacterial TMDL) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-128
· Santa Clara River Bacteria TMDL145: Fresh Waters (REC-1) and Marine Waters (REC-1)
· Santa Monica Bay Beaches Bacterial TMDL146: Marine Waters (REC-1) The bacteria water quality objectives applicable to the beneficial uses associated with these water bodies are listed in Table 11 below.

Table 11 – Los Angeles Regional Water Quality Control Board Bacteria Water Quality Objectives
Beneficial
Uses E. Coli Total
Coliform
Fecal
Coliform Enterococcus Total
Coliform*
Fresh Waters
REC-1 235/100 ml
Fresh Waters
LREC-1 576/100 ml
Fresh Waters
REC-2
4,000/100
ml
Marine Waters
REC-1
10,000/100
ml
400/100
ml 104/100 ml 1,000/100
ml
* If the fecal-to-total coliform ratio is greater than 0.1 · Source Analysis
The primary sources of elevated indicator bacteria densities include dry- weather urban runoff and stormwater conveyed to the impaired waters.

Although construction stormwater dischargers are not expected to be significant sources of indicator bacteria, they are considered Responsible Dischargers for these TMDLs.
· Waste Load Allocation Translation
The Indicator Bacteria TMDLs assign the waste load allocations in two different ways:
i. The TMDLs for the: (1) Harbor Beaches of Ventura County, (2) Santa Clara River, (3) Long Beach City Beaches, and (4) Los Angeles River 145 Los Angeles Regional Water Quality Control Board, Santa Clara River Estuary and Reaches 3, 5, 6, and 7 Indicator Bacteria TMDL (July 8, 2010), <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R10- 006_RB_BPA.pdf> [as of May 20, 2021] (Santa Clara River Bacteria TMDL) 146 Los Angeles Regional Water Quality Control Board, Santa Monica Bay Beaches Bacteria TMDL (July 2, 2014),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R12- 007_RB_BPA1.pdf>
ORDER WQ 2022-0057-DWQ
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FACT SHEET FS-129
assigns a waste load allocation of zero (0) allowable exceedance days of the Bacteria WQOs, listed in Table 11 above.
ii. The TMDLs for the: (1) Ballona Creek, Ballona Estuary, and Sepulveda Channel, (2) Malibu Creek, Lagoon, and adjacent beach, (3) Marina del Rey Harbor, Mother’s Beach, and Back Basins, (4) Los Angeles Harbor (including Inner Cabrillo Beach and Main Ship Channel), and (5) Santa Monica Bay Beaches assign waste load allocations to construction stormwater dischargers equal to the Bacteria WQOs.

The two waste load allocation definitions were translated similarly and require Responsible Dischargers to “meet and not exceed” the bacteria water quality objectives listed in Table 11. Responsible Dischargers will be required to implement minimum BMPs in order to comply with the translated waste load allocations because construction stormwater dischargers are not expected to be significant sources of indicator bacteria. This General Permit requires all dischargers to perform a pollutant source assessment and implement specific BMPs to prevent or eliminate any exceedance of water quality objectives contained within applicable TMDLs, including those for indicator bacteria. Therefore, compliance with this General Permit is consistent with the requirements and assumptions of the TMDL and sufficient to achieve compliance with the waste load allocation. · Compliance Actions and Schedule
Responsible Dischargers with an applicable TMDL for Indicator Bacteria listed in Attachment H shall comply with the requirements of this General Permit.

Responsible Dischargers that identify on-site sources of indicator bacteria in the required pollutant source assessment are to implement BMPs specific to preventing or controlling stormwater exposure to indicator bacteria. The minimum bacteria source control BMPs include QSP-conducted training of site staff, sanitary septic waste management, and routine housekeeping of identified bacteria sources. Structural BMPs such as retention, infiltration, or diversion of stormwater reduce bacteria loading to receiving waters.

Responsible Dischargers that implement a suite of minimum BMPs to control stormwater exposure to source of indicator bacteria are expected to meet the assigned waste load allocation. If a BMP is observed failing, the Responsible Discharger is to evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the waste load allocations in the future. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site-specific information about exceedances of the waste load allocation.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-130
Compliance with Indicator Bacteria TMDLs shall be achieved by the effective date of this General Permit, as shown in Table H-2 in Attachment H.
b. Chloride and Salts TMDLs
Three TMDLs for chloride and other salts (Calleguas Creek, Santa Clara River Reach 3, and Upper Santa Clara River) apply to construction stormwater dischargers. Elevated levels of chloride and salts can impair a water body’s beneficial uses associated with agricultural uses for irrigation of salt-sensitive crops and groundwater recharge to provide drinking water. i. Calleguas Creek Watershed Salts TMDL147
The Los Angeles Regional Water Quality Control Board adopted the TMDL for Boron, Chloride, Sulfate, and TDS (salts) on October 4, 2007, to protect and restore water quality in the Calleguas Creek watershed by controlling the loading and accumulation of salts.
· Source Analysis
Sources of salts in the watershed include water supply, water softeners that discharge to publicly treatment works (POTWS), POTW treatment chemicals, atmospheric deposition, pesticides and fertilizers, and indoor water use (e.g., chemicals, cleansers, food, etc.).148 The salts are then transported through POTW discharges and runoff to surface water, shallow groundwater, or accumulate on the watershed within soils.

Construction stormwater permittees are considered Responsible Dischargers for this TMDL.
· Waste Load Allocation Translation
The Calleguas Creek Watershed Salts TMDL assigns interim and final waste load allocations during dry-weather conditions, when instream flow rates are below the 86th percentile flow and there has been no measurable precipitation in the previous 24 hours.149 Both the interim and final dry-weather waste load allocations, shown in Table 12 and Table 13 below, apply in the receiving water at the base of each subwatershed.
147 Los Angeles Regional Water Board, Calleguas Creek Watershed Salts TMDL (October 4, 2007),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2007- 016_RB_BPA.pdf> [as of May 20, 2021]
148 Calleguas Creek Watershed Salts TMDL, p.3.
149 Calleguas Creek Watershed Salts TMDL, p. 7-8.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-131
Table 12 – Calleguas Creek Interim Dry-Weather Waste Load Allocations Pollutant Interim Limit
(mg/L)
Boron Total 1.3
Chloride Total 230
Sulfate Total 1289
TDS Total 1720
Table 13 – Calleguas Creek Final Dry-Weather Waste Load Allocations Receiving
Water
Critical
Condition
Flow Rate
(mgd)
Chloride
Allocation
(lb/day)
TDS
Allocation
(lb/day)
Sulfate
Allocation
(lb/day)
Boron
Allocation
(lb/day)
Simi 1.39 1,738 9,849 2,897 12
Las Posas 0.13 157 887 261 N/A
Conejo 1.26 1,576 8,931 2,627 N/A
Camarillo 0.06 72 406 119 N/A
Pleasant
Valley
(Calleguas)

0.12 150 850 250 N/A
Pleasant
Valley
(Revolon)

0.25 314 1,778 523 2
Discharges that occur during dry-weather conditions are referred to as non-stormwater discharges (NSWDs) and are only authorized by this General Permit if dischargers meet the conditions of Order, Section IV.A to control the discharge of pollutants off-site. Section IV.B of this General Permit’s Order prohibits all NSWDs not authorized under Section IV.A; therefore, all unauthorized NSWDs must be eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this General Permit, are authorized because these discharges are assumed to not commingle with stormwater associated with construction activity. The Los Angeles Regional Water Quality Control Board may impose additional requirements on NSWDs if deemed necessary per a site-specific analysis.

Wet-weather discharges are not assigned waste load allocations as flows transport a larger amount of salts at low concentrations for most construction stormwater dischargers, therefore meeting water quality objectives during wet weather.
· Compliance Actions and Schedule
Compliance with this General Permit’s requirements is consistent with the assumptions and requirements of the Calleguas Creek Salts TMDL ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-132
and is sufficient to achieve the assigned salts waste load allocations. If a BMP is observed failing, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the waste load allocations in the future. Responsible Dischargers that perform pollutant assessments and implement BMPs specific to preventing or controlling stormwater exposure with salts are expected to meet the assigned waste load allocations. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site- specific information about exceedances of the waste load allocations.

The Calleguas Creek Watershed Salts TMDL’s final compliance deadline is December 2, 2023. Therefore, the interim waste load allocations are applied to Responsible Dischargers upon the effective date of this General Permit.
ii. Santa Clara River Chloride Reach 3 TMDL150
The U.S. EPA adopted the Santa Clara River Chloride Reach 3 TMDL on June 18, 2003, to address the chloride impairment of Santa Clara River, Reach 3. Exceedances of chloride water quality standards in the Santa Clara River can impair the water’s use as agricultural irrigation supply.

The U.S. EPA’s analysis of available flow and loading data concluded that exceedances of the chloride water quality objectives are most likely to occur during low-flow conditions. Therefore, setting the TMDL and associated allocations at levels sufficient to implement the objectives during low-flow conditions will also result in attainment of the objectives during higher flow conditions.151
· Source Analysis
The Santa Clara River Chloride Reach 3 TMDL identifies two major point sources (the Fillmore and Santa Paula Water Reclamation Plants) as well as a number of minor point sources, including runoff from construction sites. Construction stormwater permittees are therefore considered Responsible Dischargers for this TMDL. Sources of salts in the watershed include water supply, water softeners that discharge to 150 United States Environmental Protection Agency IX, Total Maximum Daily Load for Chloride in the Santa Clara River, Reach 3 (June 18, 2003) <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Santa%20Clara%20River%20Reach%203%20Chloride%20TMDL/final%20SCR%20 R3%20Cl%20TMDL.pdf> [as of May 20, 2021] (Santa Clara River Chloride Reach 3 TMDL)
151 Santa Clara River Chloride Reach 3 TMDL, p. 14.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-133
publicly treatment works (POTWS), POTW treatment chemicals, atmospheric deposition, pesticides and fertilizers, and indoor water use (e.g., chemicals, cleansers, food, etc.).152 The salts are then transported through POTW discharges and runoff to surface water, shallow groundwater, or accumulate on the watershed within soils. · Waste Load Allocation Translation
The Santa Clara River Chloride Reach 3 TMDL assigns a concentration- based chloride waste load allocation of 80 mg/L to Responsible Dischargers at the construction site’s discharge locations(s) for dry- weather discharges into Santa Clara River Reach 3.

Discharges that occur during dry-weather conditions are referred to as non-stormwater discharges (NSWDs) and are only authorized by this General Permit if dischargers meet the conditions of Order, Section IV.A to control the discharge of pollutants off the site. Order, Section IV.B prohibits all NSWDs not authorized under Section IV.A; therefore, all unauthorized NSWDs must be eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this General Permit, are authorized because these discharges are assumed to not commingle with stormwater associated with construction activities.

The Los Angeles Regional Water Quality Control Board may impose additional requirements on NSWDs if deemed necessary per a site- specific analysis.
· Compliance Actions and Schedule
Compliance with this General Permit’s requirements is consistent with the assumptions and requirements of the Santa Clara River Chloride Reach 3 TMDL and is consistent with the assigned chloride waste load allocation. If a BMP is observed failing, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the waste load allocation in the future. Responsible Dischargers that perform pollutant assessments and implement BMPs specific to preventing or controlling stormwater exposure with salts are expected to meet the assigned waste load allocation. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site- specific information about exceedances of the waste load allocation.

The Santa Clara River Chloride Reach 3 TMDL does not have an implementation plan, nor compliance deadline, as it was established by the U.S. EPA rather than the Los Angeles Regional Water Quality 152 Santa Clara River Chloride Reach 3 TMDL, p. 11-12.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-134
Control Board. Therefore, the discharger shall meet the assigned waste load allocation by the effective date of this General Permit. iii. Upper Santa Clara River Chloride TMDL153
The Los Angeles Regional Water Quality Control Board adopted the Revision of the Upper Santa Clara River Chloride TMDL on October 9, 2014, to address elevated chloride concentrations causing exceedances of water quality objectives for Reaches 5 and 6 of the Santa Clara River.

Chloride-impaired water bodies that are used for agricultural irrigation supply can negatively impact the growth of salt-sensitive crops. · Source Analysis
The primary sources of chloride into Reaches 5 and 6 of the river are discharges from the Saugus and Valencia Water Reclamation Plants, contributing roughly 70 percent of the load.154 Other NPDES dischargers, including those covered under this General Permit, are considered minor contributors of chloride to the Upper Santa Clara River. Therefore, construction stormwater dischargers are considered Responsible Dischargers for this TMDL.
· Waste Load Allocation Translation
The Responsible Dischargers have been assigned a waste load allocation of 100 mg/L as 3-month rolling average. Compliance with the 3-month rolling average is currently beyond the scope of the monitoring and sampling requirements of this General Permit. A requirement to calculate a 3-month rolling average would put an undue burden on the Responsible Dischargers. Therefore, the rolling average limit will be translated into a numeric action level of 100 mg/L, to be met at the construction discharge location(s), as shown in Table 14 below.

Translating the 3-month rolling average limit into a numeric action level with the same concentration ensures that the limit is stringent enough to achieve the surface water quality objectives.

Table 14 – Upper Santa Clara River Chloride Waste Load Allocation Translation Pollutant 3-Month Rolling Average (mg/L) Numeric Action Level (mg/L)
Chloride 100 100
153 Los Angeles Regional Water Quality Control Board, Upper Santa Clara River Chloride TMDL (October 9, 2014),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R14- 010_RB_BPA.pdf> [as of March 7, 2019]
154 Upper Santa Clara River Chloride TMDL, p. 4.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-135
Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to chloride, as is required in this General Permit, are expected to meet the translated numeric action level. Therefore, compliance with this General Permit’s requirements is consistent with the assumptions and requirements of the Upper Santa Clara River Chloride TMDL and is sufficient to achieve the assigned waste load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of chloride through the required pollutant source assessment shall compare all non-visible sampling and analytical results to the chloride numeric action level. If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs implemented and identify a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action level in the future. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site-specific information about exceedances of the numeric action level.

The Upper Santa Clara River Chloride TMDL assigns the waste load allocation to Responsible Dischargers upon the effective date of the TMDL. Because the TMDL did not specify a final compliance deadline for construction stormwater dischargers, the numeric action level is applicable upon the effective date of this General Permit. c. Diazinon TMDLs
One TMDL for diazinon applies to construction stormwater dischargers.

Diazinon is an organophosphate pesticide that does not sorb to sediment but is instead mobilized through soils by dissolving in water. Discharges of stormwater containing diazinon, can cause exceedances of water quality objectives for toxicity in aquatic life in inland surface and estuarine waters.

Diazinon was once used in both agricultural and urban settings but has since been banned for non-agricultural uses by the California Department of Pesticide Regulation.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-136
i. Chollas Creek Diazinon TMDL155
The San Diego Regional Water Quality Control Board adopted the Chollas Creek Diazinon TMDL on August 14, 2002, to address the impairment of the Chollas Creek Watershed due to diazinon.
· Source Analysis
The Chollas Creek Diazinon TMDL identifies urban stormwater flows as a significant source of diazinon and lists the Construction General Permit as a means of regulating discharges of diazinon.156 Therefore, construction stormwater dischargers covered by this General Permit are considered Responsible Dischargers. However, the TMDL did not include a separate waste load allocation assigned to construction stormwater discharges.
· Compliance Actions and Schedule
Compliance with this General Permit is consistent with the requirements and assumptions of this TMDL’s waste load allocation(s). No additional requirements are incorporated into this General Permit to implement the Chollas Creek Diazinon TMDL. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site-specific information about any exceedances of the waste load allocations.
d. Nutrients TMDLs
Seven Nutrient TMDLs apply to construction stormwater discharges and incorporate waste load allocations for one or more of the following pollutants:
nitrogen compounds (e.g., ammonia, nitrate, nitrite) and phosphorous (e.g., orthophosphates). Excessive nutrient loading to water bodies and watersheds can cause eutrophic effects that negatively impact beneficial uses related to recreation, wildlife, and drinking water supply.
155 San Diego Regional Water Quality Control Board, Chollas Creek Diazinon Total Maximum Daily Load (August 14, 2002)
<https://www.waterboards.ca.gov/sandiego/water_issues/programs/tmdls/chollascreek diazinon.html> [as of May 20, 2021]. (Chollas Creek Diazinon TMDL) 156 Chollas Creek Diazinon TMDL, p. 2 and 7.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-137
i. Pajaro River Basin Nutrients TMDL157
The Central Coast Regional Water Quality Control Board adopted the Pajaro River Basin Nutrients TMDL on July 30, 2015, to address the discharges of nitrogen compounds and orthophosphate within the Pajaro River Basin. These exceedances of nutrient and nutrient-related water quality objectives can have negative impacts on beneficial uses such as municipal and domestic drinking water supply (MUN, GWR) and a range of aquatic habitats uses (WILD, COLD, WARM, MIGR, SPWN, BIOL, RARE).158
· Source Analysis
Industrial and construction NPDES-permitted stormwater discharges were determined to be potential sources of ammonia, nitrate, and orthophosphate loading to receiving waters in the Pajaro River Basin. · Waste Load Allocation Translation
This Pajaro River Basin Nutrients TMDL assigns waste load allocations as concentration-based, single sample limits to construction stormwater dischargers for ammonia, nitrate, total nitrogen, and orthophosphate, to be met in the receiving waters. Therefore, dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL, if they identify sources of these pollutants on their site through the required pollutant source assessment. The waste load allocation for un-ionized ammonia is applied to all streams within the Pajaro River Basin, while waste load allocations for nitrate, total nitrogen, and orthophosphate are specific to individual water bodies in the basin. The waste load allocations are translated from single sample limits to numeric action levels, as shown in Tables 15 through 24 below.

Table 15 – All Streams in Pajaro River Basin – Un-Ionized Ammonia Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Un-ionized Ammonia 0.025 0.025
157 Central Coast Regional Water Quality Control Board, Total Maximum Daily Loads for Nitrogen Compounds and Orthophosphate in Streams of the Pajaro River Basin (July 30, 2015),
<https://www.waterboards.ca.gov/centralcoast/water_issues/programs/tmdl/docs/pajar o/nutrients/basin_plan_amend.pdf> [as of April 29, 2022] (Pajaro River Basin Nutrients TMDL)
158 Pajaro River Basin Nutrients TMDL, p. 1.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-138
Table 16 – All Streams in Pajaro River Basin (with MUN Beneficial Uses) Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Nitrate-N 10 10
Table 17 – Pajaro River (All Reaches) and Pajaro River Estuary Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Nitrate-N 3.9 3.9
Dry-Weather
Orthophosphate-P 0.14 0.14
Wet-Weather Nitrate-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
Table 18 – Corralitos Creek and Salsipuedes Creek (All Reaches) Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Nitrate-N 1.8 1.8
Dry-Weather
Orthophosphate-P 0.14 0.14
Wet-Weather Nitrate-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
Table 19 – Beach Road Ditch and McGowan Ditch Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Nitrate-N 3.3 3.3
Dry-Weather
Orthophosphate-P 0.14 0.14
Wet-Weather Nitrate-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-139
Table 20 – Llagas Creek (Downstream of Cheseboro Reservoir), Carnadero Creek, Uvas Creek, and Furlong Creek (All Reaches) Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Nitrate-N 1.8 1.8
Dry-Weather
Orthophosphate-P 0.05 0.05
Wet-Weather Nitrate-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
Table 21 – San Juan Creek and West Branch of San Juan Creek (All Reaches) Waste Load Allocation Translation
Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Nitrate-N 3.3 3.3
Dry-Weather
Orthophosphate-P 0.12 0.12
Wet-Weather Nitrate-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
Table 22 – Tequisquita Slough Waste Load Allocation Translation Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Nitrate-N 2.2 2.2
Dry-Weather
Orthophosphate-P 0.12 0.12
Wet-Weather Nitrate-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
Table 23 – Watsonville Slough, Harkins Slough, Gallighan Slough, and Struve Slough (All Reaches) Waste Load Allocation Translations Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Total
Nitrogen-N 2.1 2.1
Dry-Weather
Orthophosphate-P 0.14 0.14
Wet-Weather Total
Nitrogen-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-140
Table 24 – Millers Canal (All Reaches) Waste Load Allocation Translations Pollutant Waste Load Allocation
Single Sample Limit (mg/L)
Numeric Action Level
(mg/L)
Dry-Weather Total
Nitrogen-N 1.1 1.1
Dry-Weather
Orthophosphate-P 0.04 0.04
Wet-Weather Total
Nitrogen-N 8.0 8.0
Wet-Weather
Orthophosphate-P 0.3 0.3
The Pajaro River Basin Nutrients TMDL assigns concentration-based waste load allocation to Responsible Dischargers for dry-weather discharges into the individual water bodies listed in Tables 15 through

24. Non-stormwater discharges are authorized in this General Permit if Order, Section IV.A terms and conditions are met to control the discharge of pollutants from the construction site. Order, Section IV.B prohibits all non-stormwater dischargers not authorized under Order, Section IV.A; therefore, all unauthorized non-stormwater dischargers must be either eliminated or have regulatory coverage under a separate NPDES permit. Authorized non-stormwater dischargers, as defined in this General Permit, are authorized because these discharges do not commingle with stormwater associated with construction activity. The Regional Water Board may impose additional requirements on non- stormwater dischargers if deemed necessary per site-specific analysis.

This General Permit requires that Responsible Dischargers meet the assigned wet-weather waste load allocations as numeric action levels at the construction site’s discharge locations, rather than the applicable receiving waters as stated in the Pajaro River Basin Nutrients TMDL.

The decision to establish numeric action levels, instead of numeric effluent limitations, was made considering that construction stormwater discharges are not expected to contribute a significant load of nutrients to receiving waters. An exceedance of the waste load allocation in the receiving waters would likely be attributed to sources other than construction stormwater discharges. Since different sources of stormwater runoff are often comingled, it is difficult to identify where the nutrient loading originates. Monitoring at the discharge location would be more indicative of an exceedance of the nutrient-related water quality objectives that is associated with a specific construction site.

Furthermore, compliance monitoring at the receiving waters can be infeasible or impractical as Responsible Dischargers may have restricted access to or be far-removed from the compliance points.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-141
· Compliance Actions and Schedule
At the time the Pajaro River Basin Nutrient TMDL was written, NPDES stormwater-permitted construction sites were generally expected to be meeting the proposed waste load allocations through the requirements of the previous permit or any subsequent Construction General Permit.

However, available information did not conclusively demonstrate that all construction sites were meeting the waste load allocations.159 Therefore, in addition to complying with the requirements of this General Permit, Responsible Dischargers identifying on-site sources of ammonia, nitrate, total phosphorus, or total nitrogen shall compare all non-visible sampling and analytical results to the numeric action levels for the identified nutrients.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to nutrient sources, are expected to meet the numeric action levels. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the numeric action levels.

The Pajaro River Basin Nutrient TMDL’s implementation schedule indicates that the waste load allocations are to be achieved within 25 years of the TMDL’s effective date July 12, 2016. Therefore, the TMDL’s compliance deadline is July 12, 2041. Since the compliance deadline is in the far future, compliance with this General Permit is considered compliance with the TMDL. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by July 12, 2041.
ii. Los Angeles Area Lakes Nutrients TMDL160
The U.S. EPA adopted the Los Angeles Area Lakes TMDL on March 26, 2012, to address the impairment of Peck Road Park Lake, Echo Park, Legg 159 Pajaro River Basin TMDL, p. 21.
160 United States EPA Region IX, Los Angeles Area Lakes Total Maximum Daily Loads for Nitrogen, Phosphorus, Mercury, Trash, Organochlorine Pesticides and PCBs (March 26, 2012),
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-142
Lakes, and Puddingstone Reservoir due to nitrogen and phosphorus. Peck Road Park Lake, Echo Park Lake, and Legg Lakes are located in the Los Angeles River watershed and Puddingstone Reservoir is located in the San Gabriel River watershed.
· Source Analysis
Nutrient loadings into Peck Road Park Lake, Echo Park, Legg Lakes, and Puddingstone Reservoir originate from a variety of sources, including discharges from storm drain outlets containing construction stormwater discharges from sites within the watershed.
· Waste Load Allocation Translation
The Los Angeles Area Lakes TMDL assigns concentration-based waste load allocations for nitrogen and phosphorus to Responsible Dischargers at the site’s discharge location(s) for construction stormwater discharges into Peck Road Park Lake, Echo Park, Legg Lakes, and Puddingstone Reservoir. Therefore, dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL. The waste load allocations for nitrogen and phosphorus differ depending on the receiving waters. The waste load allocations assigned to Responsible Dischargers for nitrogen and phosphorus are translated as shown in Table 25 and Table 26 below. The waste load allocations were set at monthly averages. The TMDL also states that “[a] three-year average will be used to evaluate compliance.” Because of the variable nature of stormwater, monthly or yearly averages are not necessarily representative of pollutant loading, and the nitrogen waste load allocation was translated into a numeric action level.

In addition to the explanation set forth in Section I.G.5.d of this Fact Sheet, implementation of the TMDL through numeric action levels is consistent with the assumptions and requirements of the waste load allocations because it is expected that compliance with this Permit will prevent exceedances of the numeric action levels. This TMDL was developed by U.S. EPA, and the Regional Board has not yet adopted an implementation plan. The TMDL also states, “if applicable water quality criteria for ammonia, dissolved oxygen and pH, and the chlorophyll-α target are met in the lake, then the total phosphorus and total nitrogen allocations are considered attained.” Because an individual discharger <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Lakes/LALakesTMDLsEntireDocument.pdf> [as of May 20, 2021] (Los Angeles Area Lakes Nutrients TMDL)
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cannot determine whether the applicable water quality criteria were being met at the time of their discharge, the waste load allocation is more appropriately translated into an action level. As further explained in Section I.G.5.d of this Fact Sheet, dischargers must take corrective actions in response to any numeric action level exceedance and this iterative process will protect water quality consistent with the requirements and assumptions set forth in this TMDL.

Table 25 – Total Nitrogen Waste Load Allocation Translation Water Body Waste Load Allocation Monthly
Average (mg/L)
Numeric Action Level
(mg/L)
Peck Road Park Lake 3.61 3.61
Echo Park Lake 1.33 1.33
Legg Lakes 1.8 1.8
Puddingstone
Reservoir 2.0 2.0
Table 26 – Total Phosphorus Waste Load Allocation Translation Pollutant Waste Load Allocation Monthly
Average (mg/L)
Numeric Effluent
Limitation (mg/L)
Peck Road Park Lake 0.37 0.37
Echo Park Lake 0.16 0.16
Legg Lakes 0.64 0.64
Puddingstone
Reservoir 0.4 0.4
This General Permit requires that Responsible Dischargers meet the assigned waste load allocations at the construction site’s discharge location(s), which is consistent with requirements and assumptions of the TMDL.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of phosphorus and nitrogen shall compare all non-visible sampling and analytical results to the numeric action levels or numeric effluent limitations for the identified nutrients. If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels or numeric effluent limitations in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to nutrient sources, are expected to meet the numeric action levels or numeric effluent ORDER WQ 2022-0057-DWQ
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limitations. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the numeric action levels or numeric effluent limitations.

The Los Angeles Regional Water Quality Control Board has not adopted an Implementation Plan or a compliance schedule for the Los Angeles Area Lakes TMDL. The numeric action levels and numeric effluent limitations described above are applicable upon the effective date of this General Permit.
iii. Los Angeles River Nutrients TMDL161
The Los Angeles Regional Water Quality Control Board adopted the Los Angeles River Nutrients TMDL on December 6, 2012, to address impairment of the Los Angeles River due to nitrogen compounds (ammonia, nitrite, and nitrate) and related effects (algae, pH, odor, and scum). · Source Analysis
The TMDL lists urban runoff as a point source which includes stormwater runoff from construction sites and other urban runoff sources such as industrial, municipal, and the California Department of Transportation.162
· Waste Load Allocation Translation
The Los Angeles River Nutrients TMDL assigns concentration-based waste load allocations for nitrogen compounds to minor point sources, including construction stormwater runoff. Therefore, construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL. The waste load allocations for ammonia are given as one-hour averages and thirty-day averages, for discharges into the Los Angeles River above LA-Glendale Water Reclamation Plant, Los Angeles River below LA-Glendale Water Reclamation Plant, or to tributaries discharging into the Los Angeles River above or below the LA-Glendale Water Reclamation Plant.

Because stormwater is an intermittent discharge, only the acute one- hour averages are appropriate to apply to Responsible Dischargers. The waste load allocation translations from one-hour averages to numeric 161 Los Angeles Regional Water Quality Control Board, Los Angeles River Nitrogen Compounds and Related Effects TMDL (July 10, 2003),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R12- 010_RB_BPA.pdf> [as of May 20, 2021] (Los Angeles River Nutrients TMDL) 162 Los Angeles River Nutrients TMDL, p. 5.

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action levels for the three different reaches of the Los Angeles River are shown in Tables 27 through 29 below. The one-hour averages are appropriate to translate into action levels because of the variable nature of stormwater, and when the non-visible sampling requirements are triggered, the effluent sampling results are not averaged.

The Los Angeles River Nutrients TMDL assigns concentration-based waste load allocations for nitrate-nitrogen, nitrite-nitrogen, and nitrate- nitrogen plus nitrite-nitrogen as thirty-day averages to Responsible Dischargers into all reaches and tributaries of the Los Angeles River.

The waste load allocations are translated to numeric action levels as shown in Table 30 below, since compliance with monthly averages is not appropriate to monitor stormwater due to its intermittent and variable nature.

The May 2021 draft of the Construction Stormwater General Permit reissuance proposed a translation of the ammonia, nitrate-nitrogen, nitrite-nitrogen, and nitrate-nitrogen plus nitrite-nitrogen waste load allocations into numeric effluent limitations as the waste load allocations were concentration-based and assigned at the point of discharge.

However, the Permit was revised to implement nitrogen-based nutrient waste load allocations as numeric action levels because numeric action levels are consistent with the assumptions and requirements of the waste load allocations.

Implementation of the TMDL through numeric action levels is consistent with the assumptions and requirements of the waste load allocation because it is expected that compliance with this Permit will prevent exceedances of the waste load allocations. Consistent with the explanation set forth in Section I.G.5.d of this Fact Sheet, the critical condition identified in the TMDL is low flow conditions (p.8). The TMDL also indicates that a majority of nutrient loading originates from major point sources such as water reclamation plants and other publicly owned treatment works,163 while sources in stormwater runoff requires further evaluation.
163 For example, the principal source of nitrogen compounds identified in this TMDL are the water reclamation plants, which contribute 84.1 percent of the total dry weather nitrogen load (p.3). The TMDL states that stormwater may also contribute nitrate loads and that further evaluation of these sources is set forth in the implementation plan, but the implementation plan does not provide further detail about stormwater as a source.

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Table 27 – Los Angeles River above LA-Glendale WRP Waste Load Allocation Translation
Pollutant Waste Load Allocation One-
Hour Average (mg/L)
Numeric Action Level
(mg/L)
Ammonia 4.7 4.7
Table 28 – Los Angeles River below LA-Glendale WRP Waste Load Allocation Translation
Pollutant Waste Load Allocation One-
Hour Average (mg/L)
Numeric Action Level
(mg/L)
Ammonia 8.7 8.7
Table 29 – Los Angeles River Tributaries Waste Load Allocation Translation Pollutant Waste Load Allocation One-
Hour Average (mg/L)
Numeric Action Level
(mg/L)
Ammonia 10.1 10.1
Table 30 – Los Angeles River Tributaries Waste Load Allocation Translation Pollutant Translated Numeric Action Level (mg/L)
Nitrate-Nitrogen 8.0
Nitrite-Nitrogen 1.0
Nitrate plus Nitrite-Nitrogen 8.0
This General Permit requires that Responsible Dischargers meet the numeric action levels at the construction site’s discharge location(s), which is consistent with requirements and assumptions of the Los Angeles River Nutrients TMDL.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of ammonia, nitrate, or nitrite shall compare all non-visible sampling and analytical results to the numeric action levels for the identified nutrients.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to nitrogen compound sources, are expected to meet the assigned numeric action levels. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the numeric action levels.

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The Los Angeles River Nutrients TMDL’s final compliance deadline for the waste load allocations was March 23, 2004. Since this compliance deadline has already passed, the numeric action levels are applicable upon the effective date of this General Permit.
iv. Machado Lake Nutrients TMDL164
The Los Angeles Regional Water Quality Control Board adopted the Machado Lake Nutrients TMDL on May 1, 2008, to address the impairment of Machado Lake due to eutrophication, algae, ammonia, and odors caused by an excess of nutrient loadings. These pollutants can have negative impacts on the beneficial uses of Machado Lake including recreation (REC- 1 and REC-2), aquatic wildlife (WARM, WILD, RARE, and WET) and water supply (MUN).
· Source Analysis
Stormwater discharges from the municipal separate storm sewer system (MS4), California Department of Transportation, and general construction and industrial discharges are identified has point sources of nutrients into Machado Lake.
· Waste Load Allocation Translation
The Machado Lake Nutrients TMDL assigns waste load allocations as concentration-based monthly averages to construction stormwater dischargers for total phosphorus and total nitrogen based on in-lake concentrations. Therefore, dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL. The waste load allocations apply to discharges to Machado Lake or through the following subdrainage systems: Drain 553, Wilmington Drain, Project 77/510, and Walteria Lake. The waste load allocations are translated to numeric action levels, as shown in Table 31 below, because this TMDL assigned these waste load allocations in the receiving water (in-lake) instead of at the point of discharge from the construction site. This TMDL assigned the waste load allocations as monthly averages; however, precipitation events are intermittent and variable. Compliance with the waste load allocations based on monthly averages is inconsistent with the monitoring and reporting requirements in this General Permit. 164 Los Angeles Regional Water Quality Board, Total Maximum Daily Load for Eutrophic, Algae, Ammonia, and Odors (Nutrient) in Machado Lake (May 1, 2008), <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2008- 006_RB_BPA.pdf> [as of May 20, 2021] (Machado Lake Nutrients TMDL) ORDER WQ 2022-0057-DWQ
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Table 31 – Machado Lake Nutrient Waste Load Allocations Translation Pollutant Waste Load Allocation Monthly
Average (mg/L)
Numeric Action Level
(mg/L)
Total Phosphorus 0.1 0.1
Total Nitrogen 1.0 1.0
This General Permit requires Responsible Dischargers to meet the numeric action levels at the construction site’s discharge location(s), which is consistent with requirements and assumptions of the TMDL. · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of phosphorus and nitrogen shall compare all non-visible sampling and analytical results to the numeric action levels for the identified nutrients.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to nutrient sources, are expected to meet the numeric action levels. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the numeric action levels.

The Machado Lake Nutrients TMDL’s effective date was March 11, 2009, with a final compliance deadline set for September 11, 2018.

Since the compliance deadline for this TMDL has passed, the discharger shall comply with the numeric action levels by the effective date of this General Permit.
v. Santa Clara River Nitrogen Compounds TMDL165
The Los Angeles Regional Water Quality Control Board adopted the Santa Clara River Nitrogen Compounds TMDL on August 7, 2003, to address nutrient-related impairment of Santa Clara River Reach 3 and Reach 7. In specific, biostimulatory substances such as ammonia, nitrate, and nitrite can lead to excessive algae growth and low dissolved oxygen in the receiving water body.
165 Los Angeles Regional Water Quality Control Board, Santa Clara River Nitrogen Compounds TMDL (August 7, 2003),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2003- 011_RB_BPA.pdf> [as of April 28, 2022]
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· Source Analysis
The primary sources of these nitrogen compounds in the Santa Clara River can be attributed to local water reclamation and treatment plants.

However, stormwater discharges were also identified as potential point sources of the nitrogen compounds.
· Waste Load Allocation Translation
The Santa Clara River Nitrogen Compounds TMDL assigns
concentration-based waste load allocations for ammonia and nitrate plus nitrite as nitrogen to construction stormwater sources regulated under NPDES permits. Therefore, construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL.

Ammonia and nitrate plus nitrite as nitrogen waste load allocations are established to address both acute effects (one-hour average concentration) and chronic effects (30-day average concentration) on aquatic life. Because stormwater is an intermittent discharge, only the acute one-hour average waste load allocations for ammonia are appropriate to apply to Responsible Dischargers. The translation of one- hour average waste load allocations to numeric action levels for the two reaches of the Santa Clara River are shown in Table 32 and Table 33 below. The one-hour average waste load allocations appropriately translate into numeric action levels due to the variable nature of stormwater. Nitrate plus nitrite as nitrogen waste load allocations were not translated as they were only established as 30-day averages.

Table 32 – Santa Clara River Reach 3 Ammonia as Nitrogen Waste Load Allocation Translation
Pollutant Waste Load Allocation One-
Hour Average (mg/L)
Numeric Action Level
(mg/L)
Ammonia 4.2 4.2
Table 33 – Santa Clara River Reach 7 Ammonia as Nitrogen Waste Load Allocation Translation
Pollutant Waste Load Allocation One-
Hour Average (mg/L)
Numeric Action Level
(mg/L)
Ammonia 5.2 5.2
This General Permit requires that Responsible Dischargers comply with the numeric action levels at the construction site discharge location(s), consistent with requirements and assumptions of the TMDL.

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allocations into numeric effluent limitations as the waste load allocations were concentration-based and assigned at the point of discharge.

However, the Permit was revised to implement nitrogen-based nutrient waste load allocations as numeric action levels because numeric action levels are consistent with the assumptions and requirements of the waste load allocations.

As set forth in Section I.G.5.d of this Fact Sheet, the source analysis found that the principal source of ammonia, nitrite, and nitrate to the Santa Clara River is discharges from water reclamation plants and publicly owned public treatment works (BPA, p.2). The TMDL also acknowledged that stormwater discharge may contribute nitrate loads.

But the allocations were set at the water quality objectives for receiving waters. The most critical conditions for water quality in the Santa Clara River are low-flow conditions, in particular at the end of the dry season (p. 72).

The TMDL also noted that “mass emission monitoring data conducted for MS4 NPDES Permit compliance indicate that the MS4 discharges are below the waste load allocation in both wet and dry weather samples.”166 (p.62) CGP dischargers subject to this TMDL are located within a MS4. · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of ammonia, nitrate, and nitrite shall compare all non-visible sampling and analytical results to the numeric action levels for the identified nutrients.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to nitrogen compound sources, are expected to meet the numeric action levels. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the numeric action levels.

The Santa Clara River Nitrogen Compounds TMDL’s compliance deadline for the waste load allocations was March 23, 2004. Since this 166 Staff Report, p. 62, available at
https://www.waterboards.ca.gov/losangeles/board_decisions/basin_plan_amendment s/technical documents/2003-011/03 0523/StaffReport06-16.pdf.

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compliance deadline has passed, the numeric effluent limitations are applicable upon the effective date of this General Permit. vi. Ventura River Algae TMDL167
The Los Angeles Regional Water Quality Control Board adopted the Ventura River Algae TMDL on December 6, 2016, to address nutrient- related impairments in the Ventura River and its tributaries. Nutrient-related listings negatively impact beneficial uses such as water contact recreation, non-water contact recreation, warm and cold freshwater habitat, wetland habitat, rare/threated/endangered species habitat, migration of aquatic organisms, and spawning.
· Source Analysis
Discharges conveyed via the municipal separate storm sewer (MS4), including stormwater and non-stormwater discharges, are estimated to contribute 21.3 percent of nutrient loading in dry weather and 28.3 percent in wet weather.
· Waste Load Allocation Translation
The Ventura River Algae TMDL assigns concentration-based waste load allocations for nitrogen and phosphorus to construction stormwater dischargers during dry and wet-weather discharges. Therefore, construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL. No translation is necessary for the dry and wet-weather waste load allocations as they were already expressed as concentration-based limitations. 1) Dry-Weather Waste Load Allocations
The Ventura River Algae TMDL assigns concentration-based waste load allocations for dry-weather total nitrogen and total phosphorus, shown in Table 34 below, with compliance assessed by averaging two grab samples.

Discharges that occur during dry-weather conditions are referred to as non-stormwater and only are authorized in this General Permit if the conditions in Order Section IV.A are met to control the discharge of pollutants from the construction site. Authorized non-stormwater discharges, as defined in this General Permit, are authorized 167 Los Angeles Regional Water Quality Control Board, Total Maximum Daily Load for Algae, Eutrophic Conditions, and Nutrients in the Ventura River and its Tributaries (December 6, 2012)
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R12- 011_RB_BPA.pdf> [as of April 28, 2022] (BPA)
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because these discharges do not commingle with stormwater associated with construction activity. Order Section IV.B prohibits all NSWDs not authorized under Section IV.A; therefore, all unauthorized NSWDs must be either eliminated or have regulatory coverage under a separate NPDES permit. A dry-weather discharge to the Ventura River watershed with concentrations greater than the total nitrogen and total phosphorus waste load allocations would therefore be prohibited. The Regional Water Board may impose additional requirements on NSWDs if deemed necessary per site- specific analysis.

Table 34 – Ventura River Algae Dry-Weather Waste Load Allocations Pollutant Total Nitrogen Waste Load
Allocation (mg/L)
Total Phosphorus
Waste Load Allocation
(mg/L)
Dry weather 1.15 0.115
2) Wet-Weather Waste Load Allocations
The wet-weather waste load allocations for nitrate plus nitrite as nitrogen, or total nitrogen where indicated, in Table 35 below are expressed as event mean concentrations or the average
concentration for all samples taken per precipitation event resulting in discharge.

Table 35 – Ventura River Algae Wet-Weather Waste Load Allocations Reach Nitrate Plus Nitrate as Nitrogen Numeric
Action Levels (mg/L)
Estuary *
Reach 1 *
Reach 2 10
Cañada Larga 10
Reach 3 5
San Antonio Creek 5
Reach 4 5
Reach 5 5
* The waste load allocations for the Estuary and Reach 1 are for t otal nitrogen at a concentration of 7.4 mg/L
The May 2021 draft of the Construction Stormwater General Permit reissuance proposed a translation for nitrate-nitrogen plus nitrite- nitrogen and total nitrogen waste load allocations into numeric effluent limitations as the waste load allocations were concentration- based and assigned at the point of discharge. However, the Permit was revised to implement nitrogen-based nutrient waste load ORDER WQ 2022-0057-DWQ
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allocations as numeric action levels because numeric action levels are consistent with the assumptions and requirements of the waste load allocations.

The TMDL states that, “[t]he discharges from the general NPDES permits are intermittent and considered negligible for the purposes of this source assessment.” (Staff Report, p.40)168 Accordingly, “[t]he loadings from the general NPDES permits [were] not quantified” in the source assessment. (Staff Report, p.40) According to the TMDL, the critical condition for the TMDL is dry weather, “and it is the dry- weather loading that results in water quality impairments.” (BPA, p.5) “The watershed nutrient wet-weather loads are generally delivered directly to the ocean and thus do not contribute to exceedance of the biostimulatory substances…”) (BPA, p.8) “Based on the linkage analysis, wet-weather loads do not have a significant impact on receiving water quality in the Ventura River and its tributaries or the Estuary and biostimulatory objectives are attained.” (Staff Report, p.79) The TMDL acknowledged that maintaining existing discharge quality would ensure that no further loading would occur in the receiving water. (BPA, p.8) The wet-weather loads were set to attain site-specific water quality objectives, (Staff Report, p.79) but “[f]or Reach 1 and Estuary, Wet-weather waste load allocations for stormwater sources are equal to existing water quality in stormwater discharges.” (BPA, p.6) This suggests that the TMDL assumed that reductions in stormwater discharges were not necessary. Dry- weather waste load allocations were set at in-stream nutrient concentrations to meet biomass numeric targets. (Staff Report, p.76) All these statements support implementation of the TMDL through numeric action levels.

Although the implementation language specifies that the TMDL should be implemented as numeric water quality-based effluent limitations, the underlying assumptions contained in the TMDL support implementation via numeric action levels.
168 Los Angeles Regional Water Quality Control Board, Algae, Eutrophic Conditions, and Nutrients Total Maximum Daily Loads for Ventura River and Its Tributaries (December 6, 2012)
<https://www.waterboards.ca.gov/losangeles/board_decisions/basin_plan_amendmen ts/technical_documents/73_New/Docs/Mar%202013/Staff%20report_Final%20120612 .pdf> [as of June 28, 2022] (Staff Report)
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· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of nitrogen and/or phosphorus shall compare all non-visible sampling and analytical results to the numeric action level for the identified nutrients, when a wet-weather discharge occurs. If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels the future.

Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to nitrogen and phosphorous sources, are expected to meet the assigned numeric action levels. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the numeric action levels.

The Ventura River Algae TMDL’s compliance deadline for the waste load allocations was June 28, 2013. Since the compliance deadline has passed, the numeric action levels are applicable upon the effective date of this General Permit.
vii. San Diego Creek and Newport Bay Watershed Nutrients TMDL169 The Santa Ana Regional Water Quality Control Board adopted the San Diego Creek and Newport Bay Watershed Nutrients TMDL in 1998 to address nutrient-related impairments in Newport Bay, San Diego Creek, and its tributaries. Nutrients contribute to seasonal algal blooms that negatively impact recreational, aesthetic, and wildlife habit beneficial uses in these waters.
· Source Analysis
The predominant source of nutrients are the tailwaters from agricultural crops and from commercial nurseries, however, runoff from construction sites can also contribute to nutrient loading through the erosion of sediment containing phosphorus.
169 Santa Ana Regional Water Quality Control Board, Nutrient TMDL for the Newport Bay/San Diego Creek Watershed (1998)
<https://www.waterboards.ca.gov/santaana/water_issues/programs/tmdl/> [as of May 20, 2021] (San Diego Creek and Newport Bay Watershed Nutrients TMDL) ORDER WQ 2022-0057-DWQ
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· Waste Load Allocation Translation
Construction stormwater dischargers are assigned an annual, mass- based waste load allocation for total phosphorus, aiming to reduce the loading of phosphorus by 50 percent. Therefore, construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for this TMDL if they identify sources of phosphorus on their site via the required pollutant source assessment.

All construction sites were expected to achieve compliance with the annual waste allocation of 12,810 lbs/year total phosphorus by 2007.

Requiring Responsible Dischargers to directly implement the waste load allocation and sample for the pollutants(s) would be impractical, costly, and not aligned with the requirements of this General Permit. It is infeasible to translate a mass-based annual waste load allocation applicable to all construction stormwater discharges to an effluent limitation that is applicable to an individual site. As mentioned in the source analysis, phosphorus loadings from construction stormwater discharges are in particulate form and associated with wet weather.

Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of phosphorus through the required pollutant source assessment are to implement BMPs specific to preventing or controlling stormwater exposure to the sources of phosphorus. Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.D.2. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations.

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actions are applicable to the Responsible Dischargers upon the effective date of this General Permit.
e. Sediment TMDLs
Twenty-five (25) sediment TMDLs are translated for this General Permit.

Sediment is the loose sand, clay, silt, and other soil particles that settle at the bottom of a body of water. Sediment can be detrimental to aquatic life by interfering with photosynthesis, respiration, growth, reproduction, and oxygen exchange in water bodies.170 Sediment can be transported in construction site discharges due to excessive erosion.171 At construction sites, the rate of erosion is increased due to increased amount of exposed and disturbed soil.

Therefore, construction sites that discharge into the watersheds of these water bodies are considered Responsible Dischargers and shall comply with the requirements set forth in these TMDLs.
i. Albion River Sediment TMDL172
The United States Environmental Protection Agency (U.S. EPA) established the Albion River Sediment TMDL on December 20, 2001, to address the impairment on the Albion River and its tributaries due to sediment.

The implementation requirements for the Albion River Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy173 adopted on November 29, 2004. The North Coast Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment- related standards by all dischargers of sediment waste.174 Construction 170 California Stormwater Quality Association, Construction Stormwater Best Management Practice Handbook (August 2011), <http://www.casqa.org/> [as of May 20, 2021] (CASQA Construction BMP Handbook)
171 CASQA Construction BMP Handbook, p. 1-7.
172 United States Environmental Protection Agency Region IX, Albion River Sediment TMDL for Sediment (December 2001),
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/albion_rive r/pdf/albionfinaltmdl.pdf> [as of May 20, 2021] (Albion River Sediment TMDL) 173 North Coast Regional Water Quality Control Board, Total Maximum Daily Load Implementation Policy Statement for Sediment-Impaired Receiving Waters in the North Coast Region (November 29, 2004).
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/sediment_t mdl_implementation/> [as of May 20, 2021] (North Coast Sediment TMDL Implementation Policy)
174 North Coast Sediment TMDL Implementation Policy, p. 3.

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stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Albion River Sediment TMDL. · Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no significant point sources of sediment in the Albion River watershed.175
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Quality Control Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit.
ii. Big River Sediment TMDL176
The U.S. EPA established the Big River Sediment TMDL on December 20, 2001, to address the impairment of Big River Sediment TMDL and its tributaries due to sediment.

The implementation requirements for the Big River Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.177 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Big River Sediment TMDL.
175 Albion River Sediment TMDL, p. 35.
176 United States Environmental Protection Agency Region IX, Big River Total Maximum Daily Load for Sediment (December 2001)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/big_river/p df/bigfinaltmdl.pdf> [as of May 20, 2021] (Big River Sediment TMDL) 177 North Coast Sediment TMDL Implementation Policy, p. 3.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-158
· Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no significant point sources of sediment in the Big River Sediment TMDL watershed.178
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit.
iii. Eel River – Lower Main Sediment TMDL179
The U.S. EPA established the Eel River – Lower Main Sediment TMDL on December 18, 2007, to address the impairment of the Lower Eel River and its tributaries due to sediment.

The implementation requirements for the Eel River – Lower Main Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy180 adopted on November 29, 2004. The North Coast Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment- related standards by all dischargers of sediment waste.181 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Eel River – Lower TMDL. 178 Big River Sediment TMDL, p. 36.
179 United States Environmental Protection Agency Region IX, Lower Eel River Total Maximum Daily Loads for Temperature and Sediment (December 18, 2007) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_l ower/pdf/LER-TMDL-final-121807-signed.pdf> [as April 28, 2022] (Eel River-Lower Main Sediment TMDL)
180 North Coast Regional Water Quality Control Board, Total Maximum Daily Load Implementation Policy Statement for Sediment-Impaired Receiving Waters in the North Coast Region (November 29, 2004)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/sediment_t mdl_implementation/> [as of May 20, 2021] (North Coast Sediment TMDL Implementation Policy)
181 North Coast Sediment TMDL Implementation Policy, p. 3.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-159
· Waste Load Allocation Translation
The source analysis supporting the allocations in Table 36 evaluated sediment loading at a subwatershed scale. The source analysis did not attempt to distinguish sediment loading at the scale of specific land ownerships nor did the analysis distinguish loading between land areas subject to NPDES regulation, or land areas not subject to NPDES regulation. Therefore, this TMDL includes separate but identical load allocations for non-point sources and waste load allocations for diffuse NPDES-permitted sources for each subarea. The diffuse NPDES- permitted pollutant sources are addressed in the statewide NPDES municipal stormwater permit for the California Department of Transportation, this statewide Construction Stormwater General Permit, the statewide Industrial Stormwater General Permit, and the City of Fortuna NPDES municipal stormwater permit.182
Table 36 – Sediment Load Allocations for the Lower Eel River Watershed and its Tributaries
Sediment Source Load Allocation
(tons/mi2/year)
1955-2003 Loading
(tons/mi2/year)
Percent
Reduction
Road (Episodic) 9 43 80 percent
Road (Chronic) 17 115 85 percent
Bank Erosion 6 21 70 percent
Construction sites covered by this General Permit are considered to be human related sources of sediment to the watershed and therefore, Responsible Dischargers. Responsible Dischargers are not to exceed the load allocations assigned to roads (episodic and chronic) and bank erosion, as the allocations assigned to timber harvest and skid trails do not typically apply to construction sites. Responsible Dischargers calculate their annual loading by multiplying the area of the site with these load allocations.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. 182 Eel River – Lower Main Sediment TMDL, p. 64.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-160
iv. Eel River – Middle Fork Sediment TMDL183
The U.S. EPA established the Eel River – Middle Fork Sediment TMDL in December 2003 to address the impairment of the Middle Fork Eel River and tributaries due to sediment.

The implementation requirements for the Eel River – Middle Fork Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy adopted on November 29, 2004. The North Coast Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment- related standards by all dischargers of sediment waste.184 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Eel River – Middle Fork Sediment TMDL. · Waste Load Allocation Translation
This TMDL identified discharges under the Construction General Permit and Caltrans Statewide Permit as current and prospective point sources that may discharge sediment in the watershed. Discharges from these point sources cannot be readily determined and possible loading from these sources is not distinguished from general management-related loading in the source analysis. Therefore, this TMDL set the load allocations for nonpoint sources to also represent waste load allocations for point sources that would be covered by general NPDES permits.185 Table 37 – Sediment Load Allocations for the Middle Fork Eel River Watershed and its Tributaries (tons/mi2/yr)
Sediment Source Black
Butte
Elk
Creek
Round
Valley
Upper
Middle
Fork
Williams/
Thatcher
Basin-
wide
Load
Small Management
Sources 7 41 9 9 19 23
Percent Reduction 0
percent
32 percent
95 percent
0 percent
89 percent
70 percent
183 United States Environmental Protection Agency Region IX, Final Middle Fork Eel River Total Maximum Daily Loads for Temperature and Sediment (December 2003) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_ middle_fork/pdf/tmdl.pdf> [as of April 28, 2022] (Eel River – Middle Fork Sediment TMDL)
184 North Coast Sediment TMDL Implementation Policy.
185 Eel River – Middle Fork Sediment TMDL, p. 45.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-161
The construction sites covered by this General Permit are considered to be human related sources of sediment to the watershed. Responsible Dischargers are not to exceed the load allocations or reductions assigned to “small management sources.” These allocations vary by subwatershed, as noted in Table 37 above. Responsible Dischargers calculate their annual loading by multiplying the area of the site with the appropriate load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. v. Eel River – Middle Main Sediment TMDL186
The U.S. EPA established the Eel River – Middle Main Sediment TMDL on December 31, 2005, to address the impairment of the Middle Main Eel River (from Dos Rios to the South Fork Eel River) and its tributaries due to sediment. A portion of the watershed is part of the Round Valley Indian Country. This TMDL does not apply to lands under tribal jurisdiction.

The implementation requirements for the Eel River – Middle Main Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.187 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Eel River – Middle Main Sediment TMDL.
186 United States Environmental Protection Agency Region IX, Final Middle Main Eel River and Tributaries Total Maximum Daily Loads for Temperature and Sediment (December 31, 2005)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_ middle_main/pdf/mainmdl-eel-final.pdf> [as of April 28, 2022] (Eel River – Middle Main Sediment TMDL)
187 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-162
· Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) for construction sites because this source is not significant.188 · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. vi. Eel River – North Fork Sediment TMDL189
The U.S. EPA established the Eel River – North Fork Sediment TMDL on December 30, 2002, to address the impairment of the North Fork Eel River and its tributaries due to sediment. These TMDLs do not apply to lands under tribal jurisdiction.

The implementation requirements for the Eel River – North Fork Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy adopted on November 29, 2004. The North Coast Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment- related standards by all dischargers of sediment waste.190 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Eel River – North Fork Sediment TMDL. · Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no significant point sources of sediment in the North Fork Eel River watershed.191
188 Eel River – Middle Main Sediment TMDL, p. 45.
189 United States Environmental Protection Agency Region IX, Final North Fork Eel River Total Maximum Daily Loads for Sediment and Temperature (December 30, 2002) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_n orth_fork/pdf/final.pdf> [as of April 28, 2022] (Eel River – North Fork Sediment TMDL) 190 North Coast Sediment TMDL Implementation Policy.
191 Eel River – North Fork Sediment TMDL, p. 23.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-163
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. vii. Eel River – Upper Main Sediment TMDL192
The U.S. EPA established the Eel River – Upper Main Sediment TMDL on December 29, 2004, to address the Impairment of the Upper Main Eel River (including Tomki Creek, Outlet Creek, and Lake Pillsbury) and its tributaries due to sediment.

The implementation requirements for the Eel River – Upper Main Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The North Coast Sediment Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.193 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Eel River – Upper Main Sediment TMDL.
· Waste Load Allocation Translation
This TMDL identified discharges under the Construction General Permit and Caltrans Statewide Permit as current and prospective point sources that may discharge sediment in the watershed and are therefore Responsible Dischargers. Discharges from these point sources cannot be readily determined and possible loading from these sources is not distinguished from general management-related loading in the source analysis. Therefore, this TMDL set the load allocations for nonpoint 192 United States Environmental Protection Agency Region IX, Final Upper Main Eel River and Tributaries (including Tomki Creek, Outlet Creek and Lake Pillsbury) Total Maximum Daily Loads for Temperature and Sediment (December 29, 2004) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_u pper_main/pdf/uer-tmdl-final-12-28.pdf> [as of May 20, 2021] (Eel River – Upper Main Sediment TMDL)
193 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-164
sources to also represent waste load allocations for point sources that would be covered by general NPDES permits.194
Table 38 – Sediment Load Allocations for the Upper Main Eel River Watershed and its Tributaries
Sediment Source Load Allocation
(tons/mi2/year)
1940-2004 Loading
(tons/mi2/year)
Percent
Reduction
Large Features (>3,000 yds3) 36 71 49 percent
Road Related (Small Features) 14 28 50 percent
Construction sites covered by this General Permit are considered to be human (land management) related sources of sediment to the watershed. Responsible Dischargers are not to exceed the load allocations assigned to road related projects or “large features” as this General Permit regulates projects that disturb an acre or greater of land.

Responsible Dischargers calculate their annual loading by multiplying the area of the site with these load allocations.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. viii. Eel River – South Fork Sediment TMDL195
The U.S. EPA established the Eel River – South Fork TMDL on December 16, 1999, to address the impairment of the South Fork Eel River and its tributaries due to sediment. These TMDLs do not apply to lands under tribal jurisdiction.

The implementation requirements for the Eel River – South Fork Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy adopted on November 29, 2004. The North Coast Sediment TMDL Implementation Policy requires the use of existing 194 Eel River – Upper Main Sediment TMDL, p. 54.
195 United States Environmental Protection Agency Region IX, South Fork Eel River Total Maximum Daily Loads for Sediment and Temperature (December 16, 1999) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_s outh_fork/pdf/eel.pdf> [as of April 28, 2022] (Eel River – South Fork Sediment TMDL) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-165
permitting and enforcement tools to pursue compliance with sediment- related standards by all dischargers of sediment waste.196 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Eel River – South Fork Sediment TMDL. · Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no significant point sources of sediment in the North Fork Eel River watershed.197
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. ix. Gualala River Sediment TMDL198
The U.S. EPA established the Gualala River Sediment TMDL in December 2001 to address the impairment of the Gualala River and its tributaries due to sediment.

The implementation requirements for the Gualala River Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL
Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.199 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Gualala River Sediment TMDL.
196 North Coast Sediment TMDL Implementation Policy.
197 Eel River – North Fork Sediment TMDL, p. 23
198 United States Environmental Protection Agency Region IX, Gualala River Total Maximum Daily Load for Sediment (December, 2001)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/gualala_riv er/110707/gualalafinaltmdl.pdf> [as of May 20, 2021] (Gualala River Sediment TMDL) 199 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-166
· Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no significant individual point sources of sediment in the Gualala River watershed.200
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. x. Mad River Sediment TMDL201
The U.S. EPA established the Mad River Sediment TMDL on December 21, 2007, to address the impairment of the Mad River and its tributaries due to sediment.

The implementation requirements for the Mad River Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.202 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Mad River Sediment TMDL.
· Waste Load Allocation Translation
The source analysis evaluated sediment loading at a subwatershed scale. The source analysis did not attempt to distinguish sediment loading at the scale of specific land ownerships nor did it distinguish loading between land areas subject to NPDES regulation and land areas not subject to NPDES regulation. Therefore, this TMDL includes separate but identical load allocations for nonpoint sources and waste 200 Gualala River Sediment TMDL, p. 17.
201 United States Environmental Protection Agency Region IX, Mad River Total Maximum Daily Loads for Sediment and Turbidity (December 21, 2007) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/mad_river/ pdf/Mad-TMDL-122107-signed.pdf> [as of May 20, 2021] (Mad River Sediment TMDL) 202 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-167
load allocations for diffuse point sources. Construction activities permitted under this General Permit are considered diffuse point sources and are therefore Responsible Dischargers for this TMDL. This TMDL assigns a waste load allocation for permitted construction activities equivalent to the load allocation for roads.203
Table 39 – Sediment Load Allocations for the Mad River Watershed Sediment Source Load Allocation
(tons/mi2/year)
1940-2004 Loading
(tons/mi2/year)
Percent
Reduction
Roads (Total Sediment) 174 1,540 89 percent
Responsible Dischargers are not to exceed the load allocations for total sediment. Responsible Dischargers are required to calculate their project site annual loading by multiplying the area of the site with this load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocation. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. xi. Mattole River Sediment TMDL204
The U.S. EPA established the Mattole River Sediment TMDL on December 30, 2002, to address the impairment of the Mattole River and its tributaries due to sediment.

The implementation requirements for the Mattole River Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL
Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.205 The discharge of soil, silt, bark, 203 Mad River Sediment TMDL, p. 91.
204 United States Environmental Protection Agency Region IX, Mattole River Total Maximum Daily Loads for Sediment and Temperature (December 30, 2002) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/mattole_riv er/110707/mattole.pdf> [as of May 20, 2021] (Mattole River Sediment TMDL) 205 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-168
sawdust, or other organic and earthen material from construction activities in quantities deleterious to fish, wildlife, or other beneficial uses is prohibited.206 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Mattole River Sediment TMDL.
· Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no point sources of sediment in the Mattole River watershed.207
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. xii. Navarro River Sediment TMDL208
The U.S. EPA established the Navarro River Sediment TMDL in December 2000 to address the impairment of the Navarro River and its tributaries due to sediment.

The implementation requirements for the Navarro River Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL
Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.209 The discharge of soil, silt, bark, sawdust, or other organic and earthen material from construction activities in quantities deleterious to fish, wildlife, or other beneficial uses is 206 Mattole River Sediment TMDL p. 9.
207 Mattole River Sediment TMDL, p. 41.
208 United States Environmental Protection Agency Region IX, Navarro River Total Maximum Daily Loads for Temperature and Sediment (December 2000) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/navarro_ri ver/110708/navarro.pdf> [as of May 20, 2021] (Navarro River Sediment TMDL) 209 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-169
prohibited.210 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Navarro River Sediment TMDL.
· Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no known point sources of sediment in the Navarro River and its tributaries.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. xiii. Noyo River Sediment TMDL211
The U.S. EPA established the Noyo River Sediment TMDL on December 16, 1999, to address the impairment of Noyo River due to sediment.

The implementation requirements for the Noyo River Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.212 The discharge of soil, silt, bark, sawdust, or other organic and earthen material from construction activities in quantities deleterious to fish, wildlife, or other beneficial uses is prohibited.213 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Noyo River Sediment TMDL. 210 Navarro River Sediment TMDL, p. 3.
211 United States Environmental Protection Agency Region IX, Noyo River Total Maximum Daily Load for Sediment (December 16, 1999)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/noyo_river/ pdf/noyo.pdf> [as of May 20, 2021] (Noyo River Sediment TMDL) 212 North Coast Sediment TMDL Implementation Policy.
213 Noyo River Sediment TMDL, p. 10.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-170
· Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources equal to zero (0) because there are no point sources of sediment in Noyo River.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. xiv. Scott River Sediment TMDL214
The North Coast Regional Water Quality Control Board adopted the Scott River Sediment TMDL on December 7, 2005, to address the impairment of Scott River due to sediment.

The implementation requirements for the Scott River Sediment TMDL in this General Permit are based on the Scott River TMDL Action Plan215 which describes the specific implementation actions necessary to fulfill the obligations of the Sediment TMDL Implementation Policy. The Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.216 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Scott River Sediment TMDL.
214 United States Environmental Protection Agency Region IX, Scott River Total Maximum Daily Load for Sediment (December 7, 2005)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/scott_river/ > [as of May 20, 2021] (Scott River Sediment TMDL)
215 North Coast Regional Water Quality Control Board, Action Plan for the Scott River Sediment and Temperature TMDLs (August 11, 2006)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/scott_river/ 060307/bpl/Basin_Plan_Language.pdf> [as of May 20, 2021] (Scott River TMDL Action Plan)
216 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-171
· Waste Load Allocation Translation
Construction sites covered by this General Permit are considered to be anthropogenic related sources of sediment to the watershed.

Responsible Dischargers are not to exceed the sum of load allocations assigned to road surface erosion and large or small discrete streamside features, which totals to 69 tons/mi2/year.217 Responsible Dischargers calculate their annual loading by multiplying the area of the site with this load allocation.
· Compliance Actions and Schedule
The Scott River TMDL Action Plan describes the implementation actions necessary to achieve the TMDL within 40 years of U.S. EPA approval of the action plan or September 8, 2046. Since the compliance deadline is in the far future, compliance with this General Permit is considered compliance with the TMDL. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by September 8, 2046. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocation. xv. Ten Mile River Sediment TMDL218
The U.S. EPA established the Ten Mile River Sediment TMDL in December 2000 to address the impairment of Ten Mile River due to sediment.

The implementation requirements for the Ten Mile River Sediment TMDL in this General Permit are based on the North Coast TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL
Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.219 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Ten Mile River Sediment TMDL.
217 Scott River TMDL Action Plan, p. 4-5.00.
218 United States Environmental Protection Agency Region IX, Ten Mile River Total Maximum Daily Load for Sediment (December 2000)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/ten_mile_ri ver/pdf/tenmile.pdf> [as of May 20, 2021] (TMDL Mile River Sediment TMDL) 219 North Coast Sediment TMDL Implementation Policy.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-172
· Waste Load Allocation Translation
This TMDL set a sediment waste load allocation for point sources at zero (0) as there are no point sources of discharge in the basin.220 · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Quality Control Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit.
xvi. Trinity River Sediment TMDL221
The U.S. EPA established the Trinity River Sediment TMDL on December 20, 2001, to address the impairment of the Trinity River and its tributaries due to sediment. This TMDL does not apply to lands under tribal jurisdiction and South Fork Trinity River.

The implementation requirements for the Trinity River Sediment TMDL in this General Permit are based on the Sediment TMDL Implementation Policy adopted on November 29, 2004. The Sediment TMDL
Implementation Policy directs the use of existing permitting and enforcement tools to pursue compliance with sediment-related standards by all dischargers of sediment waste.222
· Waste Load Allocation Translation
This TMDL identified discharges under the Construction General Permit from construction sites larger than 5 acres as current and prospective point sources that may discharge sediment in the watershed and are therefore considered Responsible Dischargers. The source analysis evaluated sediment loading at a subarea scale. The source analysis did not attempt to distinguish sediment loading at the scale of specific land ownerships nor did it distinguish between land areas subject to NPDES 220 Ten Mile River Sediment TMDL, p. 5.
221 United States Protection Agency Region IX, Trinity River Total Maximum Daily Load for Sediment (December 20, 2001)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/trinity_river /pdf/finaltrinitytmdl.pdf> [as of September 7, 2018] (Trinity River Sediment TMDL) 222 North Coast Sediment TMDL Implementation Policy.

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FACT SHEET FS-173
regulation and land areas not subject to NPDES regulation. Therefore, this TMDL includes separate but identical load allocations for nonpoint sources and waste load allocations for each subarea.223 Table 40 – TMDL and Allocations by Source Category for Upper Area (tons/mi2/year)
Source
Categories
Reference
Subwatersheds1
Westside
Tributaries2
Upper
Trinity3
East Fork
Tributaries4
Eastside
Tributaries5
Total
Management 281 105 690 65 60
Percent
Reduction 25 percent 33 percent 46
percent 83 percent 37 percent
1 Stuarts Fork, Swift Creek, Coffee Creek
2 Stuart Arm Area, Stoney Creek, Mule Creek, East Fork Stuart Fork, West Side Trinity Lake, Hatchet Creek, Buckeye Creek
3 Upper Trinity River, Tangle Blue, Sunflower, Graves, Bear Upper Trinity Mainstem Area, Ramshorn Creek, Ripple Creek, Minnehaha Creek, Snowslide Gulch Area, Scorpion Creek
4 East Fork Trinity, Cedar Creek, Squirrel Gulch Area
5 East Side Tributaries, Trinity Lake
Table 41 – TMDL and Allocations by Source Category for Upper Middle Area (tons/mi2/year)
Source
Categories
Weaver
and
Rush
Creeks
Deadwood
Creek,
Hoadley
Gulch,
and Poker
Bar Area
Lewiston
Lake
Area
Grass
Valley
Creek1
Indian
Creek
Reading
and
Browns
Creek
Total
Management 169 68 49 44 81 66
Percent
Reduction
41 percent 88 percent 74
percent
97 percent
96 percent
82 percent
1 The rate in Grass Valley Creek do not account for the amount of sediment trapped by Buckhorn Dam and Hamilton Ponds
223 Trinity River Sediment TMDL, p. 58.

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FACT SHEET FS-174
Table 42 – TMDL and Allocations by Source Category for Lower Middle Area (tons/mi2/year)
Source
Categories
Reference
Subwatersheds1
Canyon
Creek2
Upper
Tributaries3
Middle
Tributaries4
Lower
Tributaries5
Total
Management
(tons/mi2/year)
24 326 67 53 55
Percent
Reduction 0 percent 87
percent 50 percent 35 percent 39 percent
1 New River, Big French, Manzanita, North Fork, East Fork, North Fork 2 Canyon Creek
3 Dutch, Soldier, Oregon Gulch, Conner Creek Area
4 Big Bar Area, Prairie Creek, Little French Creek
5 Swede, Italian, Canadian, Cedar Flat, Mill, McDonald, Hennessy, Quinby Creek Area, Hawkins, Sharber
Table 43 – TMDL and Allocations by Source Category for Lower Area (tons/mi2/year)
Source
Categories
Reference
Subwatersheds1
Mill
Creek
and Tish
Tang
Willow
Creek
Campbell
Creek and
Supply
Creek
Lower
Mainstem
Area and
Coon Creek2
Total
Management
(tons/mi2/year)
528 210 94 1961 63
Percent
Reduction 11 percent 74
percent
91 percent 87 percent 44 percent
1 Horse Linto Creek
2 Since background rates for Lower Mainstem Area and Coon Creek were not available from GMA (2001), EPA used the same rate as was calculated for the Quinby Creek Area, which is immediately upstream, because Quinby Creek Area is comparable in size and underlain by the same geology type (Galice Formation).

The U.S. EPA expects the waste load allocations to be evaluated on a ten-year rolling average basis because of the natural variability in sediment delivery rates and does not expect the load allocation to be met for every square mile within a source category.224 Responsible Dischargers are not to exceed the load allocations or reductions assigned to the “Total Management” source category, provided in tons/mi2/yr. These allocations vary by subwatershed, as noted in Table 40 through Table 43 above. Responsible Dischargers calculate their 224 Trinity River Sediment TMDL, p. 63.

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NPDES No. CAS000002
FACT SHEET FS-175
annual loading by multiplying the area of the site with the appropriate load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H.

The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. xvii. Van Duzen River Sediment TMDL225
The U.S. EPA established the Van Duzen River Sediment TMDL on December 16, 1999, to address the impairment of the Van Duzen River and its tributaries due to sediment. These TMDLs do not apply to lands under tribal jurisdiction.

The implementation requirements for the Van Duzen River Sediment TMDL in this General Permit are based on the North Coast Sediment TMDL Implementation Policy adopted on November 29, 2004. The North Coast Sediment TMDL Implementation Policy requires the use of existing permitting and enforcement tools to pursue compliance with sediment- related standards by all dischargers of sediment waste.226 Construction stormwater dischargers covered under this General Permit are considered Responsible Dischargers for the Van Duzen River Sediment TMDL. · Waste Load Allocation Translation
This TMDL set the sediment waste load allocation for point sources at zero (0) because there are no point sources of sediment in the Van Duzen River watershed.227
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and the Sediment TMDL Requirements in Attachment H. 225 United States Environmental Protection Agency Region IX, Van Duzen River and Yager Creek Total Maximum Daily Load for Sediment (December 16, 1999) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/vanduzen_ river/pdf/vanduzen.pdf> [as of May 20, 2021] (Van Duzen River Sediment TMDL) 226 North Coast Sediment TMDL Implementation Policy.
227 Van Duzen River Sediment TMDL, p. 46.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-176
The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocation. The North Coast Sediment TMDL Implementation Policy does not include an implementation date for this TMDL. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit. xviii. Lagunitas Creek Sediment TMDL228
The San Francisco Bay Regional Water Quality Control Board adopted the Lagunitas Creek Sediment TMDL on June 11, 2014, to address the impairment of Lagunitas Creek due to sediment. Point sources of sediment in the watershed contribute minimal sediment loading and are associated with municipal and construction stormwater runoff, which are regulated through NPDES permits. Construction sites that discharge into the Lagunitas Creek watershed are therefore considered Responsible Dischargers.
· Waste Load Allocation Translation
The Lagunitas Creek Sediment TMDL set the sediment waste load allocation for construction stormwater runoff at 30 tons/year, which is equivalent to the current load from construction sites. Per the implementation measures of this TMDL, complying with the requirements of this General Permit is appropriate in addressing this waste load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocation.

The final compliance deadline for the Lagunitas Creek Sediment TMDL is June 11, 2034. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by June 11, 2034.
228 San Francisco Bay Regional Water Quality Control Board, Lagunitas Creek Fine Sediment Reduction and Habitat Enhancement Plan (March 10, 2014), <https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/TMDLs/lag unitascrksediment/LagunitasSedimentHabitat%20StaffReportPublicReviewDraft.pdf> [as of April 28, 2022] (Lagunitas Creek Sediment TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-177
xix. Napa River Sediment TMDL229
The San Francisco Bay Regional Water Quality Control Board adopted the Napa River Sediment TMDL on September 9, 2009, to address the impairment of Napa River due to sediment. Point sources of sediment that were identified as contributors of sediment to the watershed are associated with urban stormwater runoff, including construction stormwater runoff, and wastewater treatment plants, which are regulated by NPDES permits.

Construction sites that discharge into the Napa River watershed are therefore considered Responsible Dischargers.
· Waste Load Allocation Translation
The Napa River Sediment TMDL set the sediment waste load allocation for construction stormwater runoff at 500 tons/year, which is equivalent to the current load from construction sites. Per the implementation measures of this TMDL, complying with the requirements of this General Permit is appropriate in addressing this waste load allocation. · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocation.

The final compliance deadline for the Napa River Sediment TMDL is September 9, 2029. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by September 9, 2029.
xx. Pescadero and Butano Creek Sediment TMDL230
The San Francisco Bay Regional Water Quality Control Board adopted the Pescadero and Butano Creek Sediment TMDL on June 13, 2018, to 229 San Francisco Bay Regional Water Quality Control Board, Napa River Sediment Reduction and Habitat Enhancement Plan (September 15, 2009), <https://www.waterboards.ca.gov/rwqcb2/water_issues/programs/TMDLs/napariverse dimenttmdl.html#:~:text=The%20Napa%20River%20Sediment%20TMDL,healthy%20f ishery%20in%20this%20watershed.> [as of April 28, 2022] (Napa River Sediment TMDL)
230 San Francisco Bay Regional Water Quality Control Board, Pescadero-Butano Watershed Sediment TMDL and Habitat Enhancement Plan (December 11, 2018), ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-178
address the impairment of Pescadero and Butano Creek due to sediment.

The only known point sources of sediment to the watershed are associated with stormwater runoff from state highways, municipalities, and construction sites; which are regulated by NPDES permits. Construction sites that discharge into the Pescadero-Butano Creek watershed are therefore considered Responsible Dischargers.
· Waste Load Allocation Translation
The Pescadero and Butano Creek Sediment TMDL set the sediment waste load allocation for construction stormwater runoff at 150 tons/year, which is equivalent to the current load from construction sites. Per the implementation measures of this TMDL, complying with the requirements of this General Permit is appropriate in addressing this waste load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations.

The final compliance deadline for the Pescadero and Butano Creek Sediment TMDL is June 13, 2038. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by June 13, 2038.
xxi. Sonoma Creek Sediment TMDL231
The San Francisco Bay Regional Water Quality Control Board adopted the Sonoma Creek Sediment TMDL on December 10, 2008, to address the impairment of Sonoma Creek due to sediment. The only known point sources of sediment to the watershed are associated with urban stormwater runoff from state highways, municipalities, industrial facilities, and construction sites; which are regulated by NPDES permits. Construction <https://www.waterboards.ca.gov/sanfranciscobay/water_issues/programs/TMDLs/pe scadero/BPA%20FINAL.pdf> [as of May 20, 2021] (Pescadero and Butano Creek Sediment TMDL)
231 San Francisco Bay Regional Water Quality Control Board, Sonoma Creek Watershed Sediment TMDL and Habitat Enhancemnt Plan (December 12, 2008), <https://www.waterboards.ca.gov/rwqcb2/water_issues/programs/TMDLs/napariverse dimenttmdl.html> [April 28, 2022] (Sonoma Creek Sediment TMDL) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-179
sites that discharge into the Sonoma Creek watershed are therefore considered Responsible Dischargers.
· Waste Load Allocation Translation
The Sonoma Creek Sediment TMDL set the sediment waste load allocation for construction stormwater runoff at 300 tons/year, which is equivalent to the current load from construction sites. Per the implementation measures of this TMDL, complying with the requirements of this General Permit is appropriate in addressing this waste load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocation.

The final compliance deadline for the Sonoma Creek Sediment TMDL is December 10, 2028. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by December 10, 2028.
xxii. San Lorenzo River Sediment TMDL232
The Central Coast Regional Water Quality Control Board adopted the San Lorenzo River Sediment TMDL on May 16, 2003, to address the sediment related impairment of San Lorenzo River which is accelerated by anthropogenic watershed disturbances. The source analysis did not distinguish sediment loading between point and nonpoint sources, but rather assigned load allocations to water bodies within the San Lorenzo River watershed. Construction activities were included under the load allocation for Other Urban and Rural Lands sediment category. Therefore, construction sites covered under this General Permit are considered Responsible Dischargers.
232 Central Coast Regional Water Quality Control Board, San Lorenzo River Total Maximum Daily Load and Implementation Plan for Sediment Including Carbonera Creek, Lompico Creek, and Shingle Mill Creek (May 16, 2003), <https://www.waterboards.ca.gov/centralcoast/water_issues/programs/tmdl/docs/san_ lorenzo/sediment/index.html> [as of May 20, 2021] (San Lorenzo River Sediment TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-180
· Waste Load Allocation Translation
The San Lorenzo River Sediment TMDL did not establish a waste load allocation for construction sites, as it is included in the load allocation for the Other Urban and Rural Lands sediment category as indicated in Table 44 below.

Table 44 – Other Urban and Rural Land Load Allocations for San Lorenzo River Sediment TMDL
Water Body Allocation (tons/yr)
Carbonara Creek 2,622
Lompico Creek 965
Shingle Mill Creek 310
San Lorenzo River 43,368
Per the San Lorenzo River Sediment TMDL implementation plan, complying with the requirements of this General Permit is appropriate to meet the load allocations.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about excessive sediment loading.

The final compliance deadline for the San Lorenzo River Sediment TMDL is May 16, 2028. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by May 16, 2028.
xxiii. Squaw Creek Sediment TMDL233
The Lahontan Regional Water Quality Control Board adopted the Squaw Creek Sediment TMDL in April 2006 to address the impairment of Squaw Creek due to sediment. Accelerated hillslope erosion from land disturbances related to development in natural erosion-prone areas contribute to excess sediment delivery to the creek. Therefore, construction sites covered under this General Permit are considered Responsible Dischargers. 233 Lahontan Regional Water Quality Control Board, Total Maximum Daily Load for Sediment, Squaw Creek, Placer County (April 2006),
<https://www.waterboards.ca.gov/lahontan/water_issues/programs/tmdl/squaw_creek/ docs/basin_plan_amendment_final.pdf> [as of May 20, 2021] (Squaw Creek Sediment TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-181
· Waste Load Allocation Translation
There are currently no NPDES-regulated point sources in the watershed; therefore, the waste load allocation is zero (0).234 Additionally, the load allocations are not viewed as appropriate for discharge specifications in permits as they are broad estimates. Based on the assumptions for assigning the requirements of this TMDL, complying with the requirements of this General Permit is appropriate in addressing this waste load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about excessive sediment loading.

The final compliance deadline for the Squaw Creek Sediment TMDL was estimated to be 20 years, or April 2026. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by April 2026.
xxiv. Truckee River Sediment TMDL235
The Lahontan Regional Water Quality Control Board adopted the Truckee River Sediment TMDL in May 2008 to address the impairment of the Middle Truckee River Watershed due to sediment discharges during high-flow events such as those caused by thunderstorms. Primary sources of sediment include runoff from urban areas, dirt roads, legacy erosion sites, and graded ski runs. Although not explicitly stated, construction sites within urban areas or that utilize dirt roads, covered under this General Permit, can contribute to sediment loading in the Truckee River watershed and are therefore considered Responsible Dischargers.
· Waste Load Allocation Translation
This TMDL set a total waste load allocation for all sediment point sources at 4,936 tons/yr. The source analysis did not attempt to distinguish sediment loading at the scale of specific land ownerships. 234 Squaw Creek Sediment TMDL, p. 2.
235 Lahontan Regional Water Quality Control Board, Total Maximum Daily Load for Sediment Middle Truckee River Watershed (May 2008),
<https://www.waterboards.ca.gov/lahontan/water_issues/programs/tmdl/truckee/docs/ adopted_basinplan_amendment.pdf> [as of May 20, 2021] (Truckee River Sediment TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-182
NPDES-regulated point sources are expected to achieve compliance through the requirements of their respective NPDES permits. Per the implementation plan of the Truckee River Sediment TMDL, compliance with this General Permit is appropriate in addressing this waste load allocation.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about excessive sediment loading.

The final compliance deadline for the Truckee River Sediment TMDL was estimated to be 20 years, or May 2028. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance by May 2028.
xxv. San Diego Creek and Newport Bay Sediment TMDL236
The Santa Ana Regional Water Quality Control Board adopted the San Diego Creek and Newport Bay Sediment TMDL on April 16, 1999, to address the erosion in the San Diego Creek watershed and resultant siltation in Newport Bay. Anthropogenic activities such as extensive grading for development and increased runoff due to urbanization contribute to sediment loading in this watershed. Construction sites covered under this General Permit are considered Responsible Dischargers for this TMDL. · Load Allocation Translation
The San Diego Creek and Newport Bay Sediment TMDL assigns a load allocation of 13,000 tons/yr to construction sites that discharge to Newport Bay and 13,000 tons/yr to construction sites that discharge into the San Diego Creek watershed. The load allocations are shared amongst all construction sites within the Newport Bay/San Diego Creek watershed and are implemented as a 10-year running annual average.

The primary implementation measure for this TMDL is complying with the requirements of this General Permit which is expected to be appropriate to address this load allocation.
236 Santa Ana Regional Water Quality Control Board, Basin Plan Amendment Total Maximum Daily Load for Sediment in the Newport Bay/San Diego Creek Watershed (April 16, 1999)
<https://www.waterboards.ca.gov/santaana/water_issues/programs/tmdl/docs/tmdl02. pdf> [as of May 20, 2021] (San Diego Creek and Newport Bay Sediment TMDL) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-183
Responsible Dischargers shall comply with the requirements of this General Permit upon its effective date. The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about excessive sediment loading.

The San Diego Creek and Newport Bay Sediment TMDL does not include a deadline to achieve compliance. Therefore, Responsible Dischargers are required to comply with this TMDL upon the effective date of this General Permit.
xxvi. Los Peñasquitos Lagoon Sediment TMDL237
The San Diego Regional Water Quality Control Board adopted the Los Peñasquitos Lagoon Sediment TMDL on June 13, 2012, to address the impairment of Los Peñasquitos Lagoon due to sediment.

The watershed sources of sediment consist of point and non-point source discharges in the watershed draining into Los Peñasquitos Lagoon.

Anthropogenic activities such as land development exacerbate erosive processes by exposing sediment and creating more impervious surfaces which increases the velocity and volume of runoff. The Los Peñasquitos Lagoon Sediment TMDL identifies construction stormwater discharges as contributing sediment to the Lagoon and are therefore considered Responsible Dischargers.238 According to the Los Peñasquitos Lagoon Sediment TMDL staff report, the potential contribution of pollutant loadings from construction stormwater is low because non-stormwater discharges are prohibited or authorized under strict permit circumstances.239 · Waste Load Allocation Translation
The Los Peñasquitos Lagoon Sediment TMDL assigns a final waste load allocation of 2,580 tons/year to the combined responsible parties for discharges into the Los Peñasquitos Lagoon Watershed.240 Responsible 237 San Diego Regional Water Quality Control Board, Amendment to the Water Quality Control Plan for the San Diego Basin (9) to Incorporate the Sediment Total Maximum Daily Load (TMDL) for Los Peñasquitos Lagoon (June 13, 2012) <https://www.waterboards.ca.gov/sandiego/board_decisions/adopted_orders/2012/R9 -2012-0033_Attach_A.pdf> [as of May 20, 2021] (Los Peñasquitos Lagoon Sediment TMDL)
238 Los Peñasquitos Lagoon Sediment TMDL, p. A-5.
239 San Diego Regional Water Quality Control Board, Sediment TMDL for Los Peñasquitos Lagoon Staff Report (June 13, 2012),
<https://www.waterboards.ca.gov/sandiego/water_issues/programs/tmdls/docs/los_pe nasquitos_lagoon/updates071212/Staff_Report.pdf> [as of May 20, 2021] 240 Los Peñasquitos Lagoon Sediment TMDL, p. A-6.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-184
parties include: Phase I Municipal Separate Storm Sewer Systems (MS4s) co-permittees (the County of San Diego, City of San Diego, City of Del Mar, and City of Poway), Phase II MS4 permittees, the California Department of Transportation, and general construction and industrial stormwater NPDES permittees. The Phase I MS4 co-permittees and the California Department of Transportation are responsible for assuming the lead role in coordinating and carrying out the necessary actions, compliance monitoring requirements, and successful implementation of the adaptive management framework required as part of this TMDL.

Responsible Dischargers are expected to cooperate with all responsible parties to reduce their collective sediment load.

Responsible Dischargers are required to monitor sediment discharges from their sites to demonstrate progress towards compliance with final waste load allocations.241 Monitoring flow rates for construction stormwater discharges is not required for all dischargers in this General Permit and is specific to Responsible Dischargers located in the Los Peñasquitos Lagoon Watershed to assess the correlation between flow and sediment deposition in this water body.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit and are required to provide an estimate of a representative flow rate from their construction site for at least one precipitation event that generates discharge within the reporting year.

Monitoring flow rate values should be consistent with the monitoring, calculation, and reporting methods and framework used by the Phase I MS4 co-permittees. Responsible Dischargers shall submit the representative flow estimate as a PDF attachment to the Annual Report required in this General Permit.242 The Regional Water Board may assign additional monitoring, reporting, and BMP requirements upon obtaining site specific information about exceedances of the waste load allocations.

Compliance actions will be required upon the effective date of this General Permit. The final compliance deadline for the Los Peñasquitos Lagoon TMDL is July 14, 2034. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or 241 Los Peñasquitos Lagoon Sediment TMDL, p. A-8.
242 Unless another alternative electronic method in SMARTS is provided by the Water Boards.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-185
interim targets to progress towards the required final compliance by July 14, 2034.
f. Temperature TMDLs
Seven Temperature TMDLs, established by the U.S. EPA, are applicable to construction stormwater dischargers. These include the Temperature TMDLs for the Mattole River,243 Navarro River,244 Scott River245 and the Lower Main,246 Middle Main,247 North Fork,248 and Upper Main249 extents of the Eel River. 243 United States Environmental Protection Agency Region IX, Mattole River TMDL for Sediment and Temperature (December 30, 2002),
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/mattole_riv er/110707/mattole.pdf> [as of May 20,2021] (Mattole River Temperature TMDL) 244 United States Environmental Protection Agency Region IX, Navarro River TMDL for Sediment and Temperature (November 2004),
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/navarro_ri ver/110708/navarro.pdf> [as of May 20, 2021] (Navarro River Temperature TMDL) 245 North Coast Regional Water Quality Control Board, Scott River TMDL (June 2018), Ch. 4, p. 65,
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/scott_river > [as of April 28,2022] (Scott River Temperature TMDL)
246 United States Environmental Protection Agency Region IX, Lower Eel River Total Maximum Daily Loads for Temperature and Sediment (December 18, 2007) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_l ower/pdf/LER-TMDL-final-121807-signed.pdf> [as of April 28, 2022] (Eel River – Lower Main Temperature TMDL)
247 United States Environmental Protection Agency Region IX, Final Middle Main Eel River and Tributaries (from Dos Rios to the South Fork) Total Maximum Daily Loads for Temperature and Sediment (December 31, 2005)
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_ middle_main/pdf/mainmdl-eel-final.pdf> [April 28, 2022] (Eel River – Middle Main Temperature TMDL)
248 United States Environmental Protection Agency Region IX, North Fork Eel River Total Maximum Daily Loads for Sediment and Temperature (December 30, 2002) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_n orth_fork/pdf/final.pdf> [as of April 28, 2022] (Eel River – North Fork Temperature TMDL)
249 United States Environmental Protection Agency Region IX, Final Upper Main Eel River and Tributaries (including Tomki Creek, Outlet Creek and Lake Pillsbury) Total Maximum Daily Loads for Temperature and Sediment (December 29, 2004) <https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/eel_river_u per_main/pdf/uer-tmdl-final-12-28.pdf> [as of April 28, 2022] (Eel River – Upper Main Temperature TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-186
Stream temperature is a critical physical characteristic of aquatic habitats that directly impacts salmonid species. Metabolism, food requirements, growth rates, timing of adult migration upstream, timing of juvenile migration downstream, and sensitivity to diseases are all affected by stream temperature.

Although stream temperatures in Northern California naturally provide a wide range of summer conditions for rearing salmonids, the removal of riparian vegetation from road building and urbanization are amongst the sources observed to increase stream temperatures. Excessive sediment input also raises stream temperature by widening stream channels, filling pools, and eliminating riparian vegetation during flood events.250 The requirements set forth in these TMDLs apply to all point sources within the watersheds of these water bodies, which was assumed to include construction stormwater discharges. Therefore, dischargers covered under this General Permit are considered Responsible Dischargers for the Temperature TMDLs.

The Temperature TMDLs for the Klamath River, Shasta River, and the Middle Fork of the Eel River were not translated for this General Permit. These TMDLs had no known point sources that increase stream temperature and therefore did not assign any waste load allocations.
· Waste Load Allocation Translation
The Temperature TMDLs define the waste load allocations in two different ways:

1. The TMDL for the Lower Main Eel River assigns a waste load allocation of “zero (0) net increase in receiving water temperature” to construction sites subject to this General Permit.

2. The TMDLs for the Mattole River, Navarro River, Scott River and the Middle Main, North Fork, and Upper Main extents of the Eel River set the waste load allocation at zero (0), as no point sources are considered to contribute to the total loading of the respective water bodies.

The two waste load allocation definitions will be translated similarly and require that the Responsible Dischargers do not produce discharges that result in elevated stream temperatures.

The implementation requirements for the Temperature TMDLs in this General Permit are based on the Temperature Implementation Policy adopted by the North Coast Regional Water Quality Control Board on March 13, 2014. The North Coast Temperature Implementation Policy requires the use of existing permitting and enforcement tools such as NPDES permits to pursue compliance with the water quality objectives for temperature. 250 Eel River – Upper Main Temperature TMDL, p. 7.

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NPDES No. CAS000002
FACT SHEET FS-187
Additionally, the Temperature Implementation Policy251 relies on the Sediment TMDL Implementation Policy252 as a means of addressing elevated water temperatures associated with excess sediment discharges.253 The effective implementation of erosion and sediment controls, as well as meeting post-construction standards, required by this General Permit are expected to achieve the waste load allocation.

Therefore, complying with the requirements of this General Permit is consistent with the assumptions and requirements of the Temperature and Sediment TMDL Implementation Policies.
· Compliance Actions and Schedule
Compliance with this General Permit’s requirements is consistent with the assumptions and requirements of the Temperature Implementation Policy and is sufficient to achieve the assigned waste load allocation. Responsible Dischargers that implement BMPs specific to preventing or controlling stormwater exposure with sediment and comply with post-construction standards are expected to meet the assigned waste load allocation. If a BMP is observed failing, the Responsible Discharger shall evaluate the BMPs being used and implement a strategy in the site’s SWPPP to prevent potential exceedances of the waste load allocation in the future. The Regional Water Quality Control Boards may assign additional monitoring, reporting, and BMP requirements upon obtaining site-specific information about exceedances of the waste load allocation.

The North Coast Temperature Implementation Policy does not include an implementation deadline for Temperature TMDLs. Therefore, Responsible Dischargers are required to comply with the Temperature TMDLs upon the effective date of this General Permit, as listed in Table H-2 of Attachment H. 251 North Coast Regional Water Quality Control Board, Policy for the Implementation of the Water Quality Objectives for Temperature (March 13, 2014), <https://www.waterboards.ca.gov/northcoast/water_issues/programs/basin_plan/temp erature_amendment/> [as of May 20, 2021], (North Coast Temperature Implementation Policy)
252 North Coast Regional Water Quality Control Board, Total Maximum Daily Load Implementation Policy Statement for Sediment-Impaired Receiving Waters in the North Coast Region (November 29, 2004),
<https://www.waterboards.ca.gov/northcoast/water_issues/programs/tmdls/sediment_t mdl_implementation/> [as of May 20, 2021] (North Coast Sediment TMDL Implementation Policy)
253 North Coast Temperature Implementation Policy, p.4.200.

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FACT SHEET FS-188
g. Metals and Toxics TMDLs
Seventeen (17) Metals and/or Toxics TMDLs are translated for this General Permit. Metals can be toxic to aquatic life and cause impairments of beneficial uses within water bodies. Many of the artificial surfaces of the urban environment (e.g., galvanized metal, paint, automobiles, or preserved wood) contain metals, which enter stormwater as the surfaces corrode, flake, dissolve, decay, or leach.254
Other toxic pollutants in stormwater include organochlorine (OC) pesticides (chlordane, DDD, DDE, DDT, dieldrin, and toxaphene), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs), which can contribute to the impairment of beneficial uses within water bodies. The use of these pollutants has been banned for many years because of potential human health and environmental harm, however, the physio-chemical properties of the pollutants allow them to persist in the environment, bioaccumulate through the food web, and pose risks to aquatic life, wildlife, and human health.

The primary transport mechanism for the metals and toxics is the mobilization of fine sediment via stormwater and authorized NSWDs. OC pesticides, PAHs, PCBs, and metals have an affinity for organic matter and will partition from water and sorb to organic substances such as sediment. Sediment and particulates transported through construction stormwater discharges eventually settle in the bed of the receiving water.

Some of the TMDLs addressed in this Section have receiving water sediment numeric targets translated to dry-weight sediment concentration waste load allocations to be met by Responsible Dischargers at the site’s discharge location(s). The sediment targets address receiving waterbed-toxicity. Because these TMDLs associate receiving waterbed-toxicity targets to discharges of metals, OC pesticides, PAHs, and PCBs bound to sediment particulates, these TMDLs are addressed by implementing sediment control measures so that sediment-bound particulates do not leave a construction site’s area and settle in the receiving waterbed via stormwater discharges and authorized NSWDs.

This General Permit currently requires implementation of site-specific erosion and sediment controls to minimize sediment in construction runoff. The site- specific erosion control requirements address erosion in downstream channels and banks, upgradient run-on flow diversion conveyances, and cut and fill slopes.
254 CASQA, California Stormwater Best Management Practice Handbook: Construction (July 2015). <https://www.casqa.org/resources/bmp-handbooks/construction>. [as of May 20, 2021]. (CASQA Construction BMP Handbook).

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NPDES No. CAS000002
FACT SHEET FS-189
In addition, Responsible Dischargers with the potential to discharge into a TMDL watershed, water body, or reach are required to install erosion controls that will result in predicted erosion rates that are as protective as pre- construction conditions (e.g., undisturbed vegetation for the area) for each phase of the construction project. The Responsible Discharger shall use RUSLE2 to calculate the predicted erosion rates, as described in Attachment H.

Sediment produced by erosion occurring in channels is not estimated by RUSLE2255. This General Permit controls channel erosion by requiring engineered conveyance of up gradient run-on water, channel and streambank erosion control, and peak flowrate and volume controls.

Other TMDLs addressed in this Section assign waste load allocations to Responsible Dischargers in one of the following ways:
· A fixed concentration-based waste load allocation as a solution of effluent, where a concentration-based waste load allocation is assigned directly to Responsible Dischargers at the point of discharge;
· A fixed concentration-based waste load allocation as dry-weight sediment, where a concentration-based waste load allocation is assigned directly to Responsible Dischargers at the point of discharge;
· A hardness-based floating concentration waste load allocation, where the waste load allocation is hardness dependent on receiving water; or · A waste load allocation that assigned both a mass-based waste load allocation and a concentration-based waste load allocation Concentration-based waste load allocations, where applicable, were translated into numeric action levels or numeric effluent limitations for Responsible Dischargers to comply with.
i. Ballona Creek Metals TMDL256
The Los Angeles Water Quality Control Board (Los Angeles Regional Water Quality Control Board) adopted the Ballona Creek Metals TMDL on 255 USDA-Agricultural Research Service, DRAFT User’s Reference Guide Revised Universal Soil Loss Equation Version 2 (May 2008), p. 22-23 <http://fargo.nserl.purdue.edu/rusle2_dataweb/userguide/RUSLE2_User_Ref_Guide_ 2008.pdf> [as of May 20, 2021]
256 Los Angeles Regional Water Quality Control Board, Proposed Amendment to the Water Quality Control Plan – Los Angeles Region to incorporate the Ballona Creek Metals TMDL
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/Ballon a20Metals/R13-010M_RB_BPA.pdf> [as of April 28, 2022] (Ballona Creek Metals TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-190
September 6, 2007, to address the impairment of Ballona Creek and Sepulveda Canyon Channel due to copper, lead, and zinc. · Source Analysis
Storm drains convey a large percentage of metals loadings during dry weather. During wet weather, most of the metals loadings in Ballona Creek are in particulate form and are associated with wet-weather storm flows.257
· Waste Load Allocation Translation
1) Dry-Weather Waste Load Allocation
The Ballona Creek Metals TMDL assigns a dry-weather waste load allocation of zero (0) for Responsible Dischargers. Non-Stormwater Discharges (NSWDs) are authorized in this General Permit if Order, Section IV.A terms and conditions are met to control the discharge of pollutants from the construction site. Order, Section IV.B prohibits all NSWDs not authorized under Order, Section IV.A; therefore, all unauthorized NSWDs must be either eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this General Permit, are authorized because these discharges do not comingle with stormwater associated with construction activity. The Regional Water Board may impose additional requirements on NSWDs if deemed necessary per site- specific analysis.
2) Wet-Weather Waste Load Allocations
The Ballona Creek Metals TMDL assigns mass-based waste load allocations per construction area in grams per day per acre (g/day/acre) for copper, lead, and zinc. The waste load allocations for metals are shown in Table 45 below.

Table 45 – Ballona Creek and Sepulveda Channel Waste Load Allocations Pollutant Waste Load Allocation (g/day/acre)
Copper 1.673 x 10-10 x Daily storm volume (L)
Lead 9.369x 10-10 x Daily storm volume (L)
Zinc 1.279 x 10-9 x Daily storm volume (L)
Directly implementing the copper, lead, and zinc waste load allocations will result in a unique mass load for each Responsible Discharger dependent on the area of the construction site. Requiring 257 Ballona Creek Metals TMDL, p. 3.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-191
Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most metal loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment control, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the copper, lead, and zinc, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the identified metals. Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The TMDL’s final compliance deadline was January 11, 2015. Since this compliance deadline has passed, the Responsible Dischargers shall comply with the requirements of this General Permit and the RUSLE2 modeling requirements in Attachment H, Section I.G.2, upon the effective date of this General Permit.
ii. Ballona Creek Estuary Toxics TMDL258
The Los Angeles Regional Board adopted the Ballona Creek Estuary Toxics TMDL on July 7, 2005, to address the impairment of Ballona Creek and Ballona Creek Estuary (Ballona Watershed) due to cadmium, chlordane, copper, DDT, lead, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), silver, toxicity in sediment, and zinc. Chlordane and DDT are organochlorine (OC) pesticides. The Ballona Creek Estuary Toxics 258 Los Angeles Regional Water Quality Control Board, Proposed Amendment to the Water Quality Control Plan – Los Angeles Region to incorporate the Ballona Creek Estuary Toxic Pollutants TMDL
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/Ballon a%20Toxics/R13-010T_RB_BPA.pdf> [as of May 20, 2021] (Ballona Creek Estuary Toxics TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-192
does not include a TMDL for PAHs because recent data does not show PAH levels exceeding the numeric targets.259
· Source Analysis
The Ballona Creek Estuary Toxics TMDL identifies urban stormwater as a substantial source of metals and the most prevalent metals in urban stormwater are consistently associated with particulates. As a result, metals have the potential to accumulate in estuarine sediments where they may pose a toxicity risk. A majority of organic constituents in stormwater such as PAHs, phthalates, and OC compounds are also associated with particulates.260
· Waste Load Allocation Translation
The Ballona Creek Estuary Toxics TMDL assigns grouped mass-based waste load allocations per construction area in grams per year per acre (g/yr/ac) for cadmium, chlordane, copper, DDT, lead, PAHs, PCBs, silver, toxicity in sediment, and zinc. The waste load allocations for are shown in Table 46 below.

Table 46 – Ballona Creek Estuary Waste Load Allocations Pollutant Waste Load Allocation (g/yr/ac)
Cadmium 0.1
Copper 3
Lead 4
Silver 0.1
Zinc 13
Chlordane 0.00011
DDTs 0.00016
Total PCBs 0.00028
Directly implementing the waste load allocations will result in a unique mass load for each Responsible Discharger dependent on the area of construction site. Requiring Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most metal and toxic pollutant loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
259 Ballona Creek Estuary Toxics TMDL, p. 2.
260 Ballona Creek Estuary Toxics TMDL, p. 3.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-193
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the metals and toxic pollutants, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the identified metals and toxic pollutants.

Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The TMDL’s final compliance deadline was January 11, 2015. Since this compliance deadline has passed, the Responsible Dischargers shall comply with the requirements of this General Permit and the RUSLE2 modeling requirements in Attachment H, Section I.G.2, upon the effective date of this General Permit.
iii. Calleguas Creek Metals and Selenium TMDL261
The Los Angeles Water Quality Control Board (Los Angeles Water Board) adopted the Calleguas Creek Metals and Selenium TMDL on October 13, 2016, to address the impairment of Calleguas Creek, Mugu Lagoon, and Revolon Slough due to copper, mercury, nickel, and selenium. · Source Analysis
The significant sources of metals and selenium in the watershed include urban runoff, agricultural runoff, POTW effluent, and groundwater. Open space was also a significant source for mercury.

Higher loads were delivered during wet weather for all constituents due to the association between metals and particulate matter. The source analysis indicates that naturally occurring metals and selenium may be contributing sources in soil. The Calleguas Creek Metals and Selenium 261 Los Angeles Regional Water Quality Control Board, Total Maximum Daily Load for Metals and Selenium in the Calleguas Creek, its Tributaries and Mugu Lagoon <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R16- 007_RB_BPA.pdf> [as of May 20, 2021] Calleguas Creek Metals and Selenium TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-194
TMDL includes plans for special studies to further assess natural sources of metals in soil.262
· Waste Load Allocation Translation
1) Dry-weather Waste Load Allocations
The Calleguas Creek Metals and Selenium TMDL assigns
concentration-based waste load allocations for dry-weather. Non- Stormwater Discharges (NSWDs) are authorized in this General Permit if Order, Section IV.A terms and conditions are met to control the discharge of pollutants from the construction site. Order, Section IV.B prohibits all NSWDs not authorized under Order, Section IV.A; therefore, all unauthorized NSWDs must be either eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this General Permit, are authorized because these discharges do not commingle with stormwater associated with construction activity. The Regional Water Board may impose additional requirements on NSWDs if deemed necessary per site-specific analysis.
2) Wet-weather Interim Waste Load Allocations for Copper The Calleguas Creek Metals and Selenium TMDL assigns an interim concentration-based wet-weather waste load allocation for copper to “Permitted Stormwater Dischargers (PSDs)” to be met at the receiving water. Responsible Dischargers are identified as a PSDs as defined in the Calleguas Creek Metals and Selenium TMDL.263 The interim wet daily maximum concentration-based waste load allocation will be translated into a numeric action level for Responsible Dischargers until the final waste load allocations apply. The interim waste load allocations were translated into numeric action levels as shown in Table 47 below. The numeric action levels are in mg/L to be consistent with the reporting units in SMARTS.

Table 47 – Calleguas Creek, Conejo Creek, and Revolon Slough Interim Wet- Weather Waste Load Allocations
Water body Waste Load Allocation
for Copper (ug/L)
Total Copper Numeric
Action Level (mg/L)
Calleguas and Conejo
Creek 204 0.204
Revolon Slough 204 0.204
262 Calleguas Creek Metals and Selenium TMDL, p. 4, p. 13. 263 Calleguas Creek Metals and Selenium TMDL, p. 19.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-195
3) Wet-weather Final Waste Load Allocations Copper, Nickel, and Selenium
The Calleguas Creek Metals and Selenium TMDL assigns a final mass-based wet-weather waste load allocations for copper, nickel, and selenium in pounds per day to “Permitted Stormwater Dischargers (PSDs)” to be met in the water column of Calleguas Creek or Revolon Slough. The waste load allocation for copper, nickel, and selenium are shown in Table 48 below.

Table 48 – Calleguas Creek, Conejo Creek, and Revolon Slough Interim Wet- Weather Waste Load Allocations
Pollutant
Waste Load Allocation for
Calleguas Creek and Conejo
Creek (lbs/d)
Waste Load Allocation for
Revolon Slough (lbs/d)
Copper* (0.00054*Q^2*0.032*Q – 0.17)*WER
– 0.06 (0.0002*Q2+0.0005*Q)*WER
Nickel** 0.014*Q^2+0.82*Q 0.027*Q^2+0.47*Q
Selenium** (a) 0.027*Q^2+0.47*Q
*The approved site-specific WER of 1.51 for Mugu Lagoon is used to calculate the assigned waste load allocations for discharges to Calleguas and Conejo Creek to ensure the downstream standard is achieved. Permitted stormwater dischargers may apply a WER of up to 3.69 for discharges to upstream reaches, with the exception of Reaches 4 and 5, to calculate the assigned waste load allocations. If a WER of greater than 1.51 is applied, permitted stormwater dischargers shall be required to provide detailed quantitative analysis to demonstrate that the waste load allocations as modified by the WER are protective of downstream reaches. No site specific WER for Revolon Slough was approved so default WER value of 1 is applied. Regardless of the final WERs, total copper loading shall not exceed current loading. **Current loads do not exceed loading capacity during wet weather. Sum of all loads cannot exceed loads presented in the table. Q: Daily storm volume (cfs). (a) Selenium allocations have not been developed for this reach as it is not on the 303(d) list.

Directly implementing the final copper, nickel, and selenium waste load allocations will result in a unique mass load for each Responsible Discharger dependent on the daily stormwater flows and area of construction site. Requiring Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most metal loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-196
a) Comply with the site-specific erosion and sediment control, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
4) Wet-weather Interim Limits and Final Waste Load Allocations for Mercury
The Calleguas Creek Metals and Selenium TMDL assigns mass- based interim and final waste load allocations for mercury pounds per year (lbs/yr) to “Permitted Stormwater Dischargers (PSDs)” to be met at the receiving water. The waste load allocations for mercury are shown in Table 49 below.

Table 49 – Interim Limits and Final Waste Load Allocations for Mercury in Suspended Sediment for Calleguas Creek and Revolon Slough Flow Range
Calleguas
Creek Interim
(lb/yr)
Calleguas
Creek Final
(lb/yr)
Revolon
Slough
Interim (lb/yr)
Revolon
Slough Final
(lb/yr)
0-15,000
Million Gallons
per Year

3.3 0.4 1.7 0.1
15,000-25,000
Million Gallons
per Year

10.5 1.6 4 0.7
Above 25,000
Million Gallons
per Year

64.6 9.3 10.2 1.8
Directly implementing the copper and nickel waste load allocations will result in a unique mass load for each Responsible Discharger dependent on the range of stormwater flows and area of
construction site. Requiring Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most metal loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment control, and post-construction requirements in this General Permit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-197
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
The TMDL’s interim compliance deadline was March 27, 2007. Since this compliance deadline has passed, the interim waste load allocations shall be met by the effective date of this General Permit.

Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers shall compare all non-visible sampling and analytical results to the numeric action level for copper. If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the waste load allocations in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to copper, nickel, selenium, and mercury sources are expected to meet the assigned waste load allocations.

The TMDL’s final compliance deadline was March 27, 2022. Since this compliance deadline has passed, the Responsible Dischargers shall comply with the erosion and sediment control requirements of this General Permit and RUSLE2 modeling requirements in Attachment H, Section I.G.2, upon the effective date of this General Permit. iv. Calleguas Creek OC Pesticide and PCBs TMDL264
The Los Angeles Regional Water Quality Control Board adopted the Calleguas Creek OC Pesticide and PCBs TMDL on June 9, 2006, to address the impairment of Calleguas Creek Watershed due to organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs).

Eleven of fourteen reaches in the watershed are identified as impaired for these toxic pollutants on the 2002 303(d) list.
264 Los Angeles Regional Water Quality Control Board, Total Maximum Daily Loads (TMDLs) for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs) and Siltation in Calleguas Creek, its Tributaries, and Mugu Lagoon (July 7, 2005), <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/2005- 010_RB_BPA.pdf> [as of May 20, 2021] (Calleguas Creek OC Pesticides and PCBs TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-198
· Source Analysis
The largest sources of OC pesticides and PCBs in the watershed were estimated to be agricultural runoff and residues from past uses, respectively. Urban runoff is considered a minor source of OC pesticides and PCBs. Both impairing contaminants are known to bind to sediments and fine particles, which are transported to the watershed through runoff and erosion.
· Waste Load Allocation Translation
The Calleguas Creek OC Pesticide and PCBs TMDL assigns interim and final waste load allocations for pollutants in sediment for stormwater permittees, shown in Table 50 and Table 51 below. Although not specifically identified in the TMDL, waste load allocations were interpreted as applicable to construction stormwater dischargers due to the sediment and erosion intensive activities associated with construction. Therefore, construction stormwater dischargers are considered Responsible Dischargers for the Calleguas Creek OC Pesticide and PCBs TMDL.

Table 50 – Interim Sediment Waste Load Allocations (ng/g) for Stormwater Permittees
Constituent Mugu
Lagoon*
Calleguas
Creek
Revolon
Slough
Arroyo
Las
Posas
Arroyo
Simi
Conejo
Creek
Chlordane 3.3 3.3 0.9 3.3 3.3 3.3
4,4-DDD 2.0 2.0 2.0 2.0 2.0 2.0
4,4-DDE 2.2 1.4 1.4 1.4 1.4 1.4
4,4-DDT 0.3 0.3 0.3 0.3 0.3 0.3
Dieldrin 4.3 0.2 0.1 0.2 0.2 0.2
PCBs 180.0 120.0 130.0 120.0 120.0 120.0
Toxaphene 360.0 0.6 1.0 0.6 0.6 0.6
* Mugu Lagoon subwatershed includes Duck Pond/Agricultural Drain/Mugu/Oxnard Drain #2
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-199
Table 51 – Final Sediment Waste Load Allocations (ng/g) for Stormwater Permittees
Constituent Mugu
Lagoon*
Calleguas
Creek
Revolon
Slough
Arroyo
Las
Posas
Arroyo
Simi
Conejo
Creek
Chlordane 3.3 3.3 0.9 3.3 3.3 3.3
4,4-DDD 2.0 2.0 2.0 2.0 2.0 2.0
4,4-DDE 2.2 1.4 1.4 1.4 1.4 1.4
4,4-DDT 0.3 0.3 0.3 0.3 0.3 0.3
Dieldrin 4.3 0.2 0.1 0.2 0.2 0.2
PCBs 180.0 120.0 130.0 120.0 120.0 120.0
Toxaphene 360.0 0.6 1.0 0.6 0.6 0.6
* Mugu Lagoon subwatershed includes Duck Pond/Agricultural Drain/Mugu/Oxnard Drain #2
Compliance with the sediment-based waste load allocations is measured as an in-stream annual average at the base of each subwatershed where the dischargers are located. Requiring Responsible Dischargers to sample for the pollutant(s) within the receiving waters would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, OC pesticide and PCB loading are associated with sediment and fine particles transported by runoff. Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of organochlorine compounds associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the organochlorine compounds. Furthermore, Responsible Dischargers are to comply with the RUSLE 2 modeling requirements in Attachment H, Section I.G.2.

The Calleguas Creek OC Pesticide and PCBs TMDL’s interim compliance deadline for the TMDLs was March 26, 2007. Since the deadline has already passed, Responsible Dischargers shall comply with ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-200
the interim waste load allocations through the requirements of this General Permit and the RUSLE2 modeling requirements in Attachment H, Section I.G.2, upon the effective date of this General Permit.

Compliance with the final waste load allocations shall be achieved by March 26, 2027.
v. Colorado Lagoon Toxics TMDL265
The Los Angeles Regional Water Quality Control Board adopted the Colorado Lagoon Toxics TMDL on October 1, 2009, to address the impairment of Colorado Lagoon due to metals, organochlorine (OC) pesticides (chlordane, DDT, and dieldrin), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and sediment toxicity. · Source and Linkage Analysis
The Colorado Lagoon watershed is divided into five sub-basins that discharge stormwater and urban dry weather runoff to Colorado Lagoon.266 The impairing contaminants in sediment are associated with fine-grained particles that are primarily delivered to the sediments through suspended solids in stormwater and urban runoff.267 Therefore, construction sites covered under this General Permit are considered Responsible Dischargers for the Colorado Lagoon Toxics TMDL. · Waste Load Allocation Translation
The Colorado Lagoon Toxics TMDL assigns concentration-based waste load allocations for lead, zinc, OC pesticides, PAHs, and PCBs to be met at the construction site’s discharge point(s) for discharges into Colorado Lagoon.268 The waste load allocations are shown in Table 52 below. 265 Los Angeles Regional Water Quality Control Board, Total Maximum Daily Load for Organochlorine (OC) Pesticides, Polychlorinated Biphenyls (PCBs), Sediment Toxicity, Polycyclic Aromatic Hydrocarbons (PAHs), and Metals for Colorado Lagoon (October 1, 2009),
<https://www.waterboards.ca.gov/water_issues/programs/tmdl/docs/coloradolagoonto xicity/signedresolutionr09_005_amendments.pdf> [as of April 29, 2022] (Colorado Lagoon Toxics TMDL)
266 Colorado Lagoon Toxics TMDL, p. 3.
267 Colorado Lagoon Toxics TMDL, p. 4.
268 Colorado Lagoon Toxics TMDL, p. 5, 10.

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FACT SHEET FS-201
Table 52 – Colorado Lagoon Waste Load Allocations
Pollutants Waste Load Allocation Suspended Sediment-
Associated Contaminants (ug/dry kg)
Chlordane 0.50
Dieldrin 0.02
Lead 46,700.00
Zinc 150,000.00
PAHs 4,022.00
PCBs 22.70
DDT 1.58
Requiring Responsible Dischargers to sample for the pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most metal loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the toxic pollutants associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the organochlorine compounds. Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The final compliance deadline for the Colorado Lagoon Toxics TMDL was July 28, 2018. Since the deadline has already passed, Responsible Dischargers shall comply with the waste load allocations through the requirements of this General Permit and the RUSLE2 modeling requirements in Attachment H, Section I.G.2, upon the effective date of this General Permit.

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FACT SHEET FS-202
vi. Los Angeles Area Lakes Waters Toxics TMDL269
The U.S. EPA adopted the Los Angeles Area Lakes Toxics TMDL on March 26, 2012, to address the impairment in three of the nine assessed lakes in the Los Angeles Region due to organochlorine (OC) pesticides (chlordane, dieldrin, DDT) and polychlorinated biphenyls (PCBs). The three identified lakes for OC pesticides and PCBs impairments are Peck Road Park Lake, Echo Park Lake, and Puddingstone Reservoir. Peck Road Park Lake and Echo Park Lake are located in the Los Angeles River watershed.

Puddingstone Reservoir is located in the San Gabriel River watershed. · Source Analysis
The manufacturing and use of OC pesticides and PCBs are currently banned and no additional allowances for new sources of discharges are expected in the Los Angeles Area Lakes Toxics TMDL. Source control BMPs and pollutant removal are the most suitable courses of action to reduce OC pesticides and PCBs. The TMDL identified many historic and current loadings of pollutants into Peck Road Park Lake, Echo Park Lake, and Puddingstone Reservoir including construction sites that would be covered under this General Permit. Therefore, construction stormwater dischargers are considered Responsible Dischargers for the Los Angeles Area Lakes Toxics TMDL.
· Waste Load Allocation Translation
The Los Angeles Area Lakes TMDL assigns concentration-based waste load allocations for OC pesticides and PCBs in the water column to be met at the construction site’s discharge location(s) into Peck Road Park Lake, Echo Park Lake, and Puddingstone Reservoir, summarized in Table 53 through Table 55 below.

Table 53 – Peck Road Park Lake Toxics Waste Load Allocation Pollutant Waste Load Allocation – Water Column
(mg/L)
Chlordane 5.9 X 10-7
Dieldrin 1.4 X 10-7
Total DDTs 5.9 X 10-7
Total PCBs 1.7 X 10-7
269 Los Angeles Regional Water Quality Control Board, Los Angeles Area Lakes Waters Toxics TMDL (May 2011)
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Lakes/LALakesTMDLsEntireDocument.pdf> [as of April 28, 2022] (Los Angeles and Long Beach Harbor Water TMDL)
ORDER WQ 2022-0057-DWQ
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FACT SHEET FS-203
Table 54 – Echo Park Lake Toxics Waste Load Allocation
Pollutant Waste Load Allocation – Water Column
(mg/L)
Chlordane 5.9 X 10-7
Dieldrin 1.4 X 10-7
Total PCBs 1.7 X 10-7
Table 55 – Puddingstone Reservoir Toxics Waste Load Allocation Pollutant Waste Load Allocation – Water Column
(mg/L)
Chlordane 5.7 X 10-7
Dieldrin 1.4 X 10-7
Total DDTs 5.9 X 10-7
Total PCBs 1.7 X 10-7
The May 2021 draft of the Construction Stormwater General Permit reissuance proposed a translation of the waste load allocations into numeric effluent limitations. However, the translated numeric effluent limitations for chlordane, DDT, dieldrin, and PCBs in the Los Angeles Area Lakes Toxics TMDL were below the respective reporting limits for the constituents and would render determining compliance at the point of discharge infeasible.

Dischargers that discharge to the applicable Los Angeles Area Lakes waterbodies are to conduct a soil screening investigation for chlordane, DDT, dieldrin, and PCBs (as applicable) as part of the pollutant source assessment to determine whether they are Responsible Dischargers per Attachment H, Section I.G.5. Dischargers are considered Responsible Dischargers if the TMDL analytes are measured above their respective reporting limits and will be required to comply with a numeric effluent limitation of 100 mg/L total suspended solids (TSS) as the applicable limitation for each of the applicable TMDL-pollutants identified through the soil screening investigation.

State Water Board staff reviewed literature270 and concluded that measurements of total suspended solids at the point of discharge, 270 Nasrabadi T, Ruegner H, Schwientek M, Bennett J, Fazel Valipour S, Grathwohl P (2018) “Bulk metal concentrations versus total suspended solids in rivers: Time- invariant & catchment-specific relationships.”;
Washington Department of Ecology (2004) “A Total Maximum Daily Load Evaluation for Chlorinated Pesticides and PCBs in the Walla Walla River.”; Angela Gorgoglione, Fabián A. Bombardelli, Bruno J. L. Pitton, Lorence R. Oki, Darren L. Haver and Thomas M. Young (2018) “Role of Sediments in Insecticide Runoff from Urban Surfaces: Analysis and Modeling.”
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FACT SHEET FS-204
following a non-visible pollutant monitoring trigger, are the most reasonable way to assess presence of chlordane, DDT, dieldrin, and PCBs, as these organic pollutants are readily sorbed to sediment.

The measurement of total suspended solids at or above of 100 mg/L is an appropriate indicator of the presence of chlordane, DDT, dieldrin, and PCBs in runoff, if the pre-project soil analysis (described in Attachment H, Section I.G.5) demonstrated these pollutants are present in the soil.

There is a strong positive correlation between total suspended solids and chlordane, DDT, dieldrin, and PCBs, indicating that concentrations of pollutants increase and decline proportionally with the TSS concentrations. If the constituents were measured in the soil at or above the reporting limit, a small fraction will be in the TSS sample as well. · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of toxic pollutants associated with the impaired water bodies, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the metals.

Furthermore, the Responsible Discharger shall compare all non-visible sampling and analytical results to the TSS numeric effluent limitation to address toxic pollutants associated with the impairment of the water body. Exceedances of the TSS numeric effluent limitation equates to an exceedance of each applicable TMDL-specific pollutant identified in the soil screening investigation.

The Los Angeles Regional Water Quality Control Board has not adopted an Implementation Plan or a compliance schedule for the toxic pollutants addressed by the Los Angeles Area Lakes Toxics TMDL. Therefore, Responsible Dischargers are required to achieve compliance with the TSS numeric effluent limitation by the effective date of this General Permit.
vii. Los Angeles and Long Beach Harbor Waters TMDL271
The Los Angeles Regional Water Quality Control Board adopted the Los Angeles and Long Beach Harbor Waters TMDL on May 5, 2011, to address 271 Los Angeles Regional Water Quality Control Board, Total Maximum Daily Load for Toxic Pollutants in Dominguez Channel and Greater Los Angeles and Long Beach Harbor Waters (May 2011)
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R11- 008_RB_BPA.pdf> [as of May 20, 2021] (Los Angeles and Long Beach Harbor Waters TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-205
the impairment and affected benthic communities of the Dominguez Channel, Greater Los Angeles, and Long Beach Harbor Waters due to cadmium, certain polyaromatic hydrocarbon (PAH) compounds, chlordane, chromium, copper, DDT, dieldrin, lead, mercury, polychlorinated biphenyls (PCBs), toxaphene, toxicity, and zinc.
· Source Analysis
Chromium, copper, lead, mercury, PAHs, and zinc are currently deposited into the watershed via urban runoff and then washed into storm drains and channels that discharge to the Dominguez Channel and Greater Harbor Waters. Organochlorine (OC) pesticides (chlordane, DDT, dieldrin) and PCBs are legacy pollutants and remain present in the environment. Urban runoff and rainfall mobilize OC pesticides, PAHs, and PCBs bound to fine-grained particles, which are then washed into storm drains and channels that discharge to the Dominguez Channel and Greater Harbor Waters. Runoff from construction sites covered under this General Permit has the potential to transport these toxic pollutants into the waters. Therefore, construction stormwater dischargers are considered Responsible Dischargers for the Los Angeles and Long Beach Harbor Waters Toxics TMDL.
· Waste Load Allocation Translation
1) Dominguez Channel and Torrance Lateral Freshwater Wet Weather Interim Waste Load Allocations
This TMDL assigns interim concentration-based waste load allocations for copper, lead, and zinc to Responsible Dischargers to be met at the construction site’s discharge location(s) for discharges into the Dominguez Channel or Torrance Lateral. The interim concentration-based waste load allocations will be translated to numeric action levels as an interim target for Responsible Dischargers until the final waste load allocations apply. The compliance deadline of the interim waste load allocations is upon effective date of the TMDL and therefore, apply at that time. The interim numeric action levels are shown in Table 56 below.

Table 56 – Dominguez Channel and Torrance Lateral Interim Waste Load Allocation Translation
Pollutant Waste Load Allocation
(ug/L)
Interim Numeric Action Level
(mg/L)
Total Copper 207.51 0.20751
Total Lead 122.88 0.12288
Total Zinc 898.87 0.89887
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-206
2) Dominguez Channel and Torrance Lateral Wet-Weather Final Waste Load Allocations
This TMDL assigns wet-weather final concentration-based waste load allocations for copper, lead, and zinc to Responsible Dischargers to be met at the construction site’s discharge location(s) for discharges into the Dominguez Channel (above Vermont Avenue).

Exxon Mobil Torrance Refinery and “all other dischargers” are assigned concentration-based waste load allocations of copper, lead, and zinc equal to the sediment targets to be met at the construction site’s discharge location(s) for discharges into the Dominguez Channel and Torrance Lateral, shown in Table 57 below.

Responsible Dischargers are assumed to be included in the “all other dischargers” definition. The concentration-based waste load allocations are translated into numeric effluent limitations. However, the numeric effluent limitations are not immediately effective because the compliance deadline for attaining the waste load allocation for dischargers into Dominguez Channel and Torrance Lateral is beyond this General Permit’s term.

Table 57 – Dominguez Channel and Torrance Lateral Final Waste Load Allocation Pollutant Waste Load Allocation* (mg/L)
Total Copper 0.0097
Total Lead 0.0427
Total Zinc 0.0697
*Hardness used = 50 mg/L. Recalculated concentration-based allocations using ambient hardness at the time of sampling are considered consistent with the assumptions and requirements of these waste load allocations. In addition to the waste load allocations above, samples collected during flow conditions less than the 90th percentile of annual flow rates must demonstrate that the acute and chronic hardness dependent water quality criteria provided in the CTR are achieved.

The May 2021 draft of the Construction Stormwater General Permit reissuance proposed a translation for the final total copper, lead, and zinc waste load allocations into numeric effluent limitations as the waste load allocations were concentration-based and assigned at the point of discharge. However, this General Permit incorporates a soil screening investigation and a total suspended solids numeric effluent limitation to assess compliance with the final waste load allocations for total copper, lead, and zinc.

Starting at the effective date of the final waste load allocations, March 23, 2032, dischargers that discharge to the Dominguez Channel and Torrance Lateral are to conduct a soil screening investigation for ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-207
copper, lead, and zinc as part of the pollutant source assessment to determine whether they are Responsible Dischargers per Attachment H Section I.G.5. Dischargers are considered Responsible Dischargers if the TMDL analytes are measured above the analytical reporting limit and will be required to comply with a numeric effluent limitation of 100 mg/L total suspended solids (TSS) as the applicable limitation for each of the applicable TMDL-pollutants identified through the soil screening investigation, instead of the numeric effluent limitations for total copper, lead, and zinc.

State Water Board staff reviewed literature272 and concluded that measurements of TSS at the point of discharge, following a non- visible pollutant monitoring trigger, are the most reasonable way to assess the presence of copper, lead, and zinc, as these metals are a readily sorbed to sediment, which is the most common pollutant discharged from construction sites and can be managed effectively with BMPs.

Staff determined the measurement of TSS at or above 100 mg/L is an appropriate indicator of the presence of copper, lead, and zinc in runoff, if the pre-project soil monitoring (described in Attachment H, Section I.G.5) demonstrated these pollutants are present in the soil.

There is a strong positive correlation between TSS and metals, indicating that concentrations of pollutants increase and decline proportionally with the TSS concentrations. If the constituents were measured in the soil at or above the analytical reporting limit, a small faction will be in the TSS sample as well.
3) Dominguez Channel Estuary and Greater Los Angeles and Long Beach Harbor Waters Interim Sediment Waste Load Allocations This TMDL assigns concentration-based interim sediment waste load allocations for copper, lead, zinc, DDT, PAHs, and PCBs to Responsible Dischargers for discharges into the Dominguez Channel Estuary and Greater Harbor Waters, shown in Table 58 below. 272 Nasrabadi T, Ruegner H, Schwientek M, Bennett J, Fazel Vailpour S, Grathwohl P (2018) “Bulk metal concentrations versus total suspended solids in rivers: Time- invariant & catchment-specific relationships.”
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-208
Table 58 – Dominguez Channel Estuary and Greater Harbor Waters Interim Sediment Waste Load Allocations in mg/kg sediment
Water Body Copper Lead Zinc DDT PAHs PCBs
Dominguez Channel
Estuary 220.0 510.0 789.0 1.727 31.60 1.490
Long Beach Inner Harbor 142.3 50.4 240.6 0.070 4.58 0.060 Los Angeles Inner Harbor 154.1 145.5 362.0 0.341 90.30 2.107 Long Beach Outer Harbor
(inside breakwater) 67.3 *46.7 150 0.075 *4.022 0.248
Los Angeles Outer Harbor
(inside breakwater) 104.1 *46.7 150 0.097 *4.022 0.310
Los Angeles River Estuary 53.0 *46.7 183.5 0.254 4.36 0.683 San Pedro Bay
Near/Offshore Zones 76.9 66.6 263.1 0.057 *4.022 0.193
Los Angeles Harbor –
Cabrillo Marina 367.6 72.6 281.8 0.186 36.12 0.199
Los Angeles Harbor –
Consolidated Slip 1470.0 1100.0 17050 1.724 386.00 1.920 Los Angeles Harbor –
Inner Cabrillo Beach 129.7 *46.7 163.1 0.145 *4.022 0.033 Fish Harbor 558.6 116.5 430.5 40.5 2102.7 36.6
*Values are also the final allocation
Directly implementing the final waste load allocations would be impractical, costly, and not aligned with the monitoring requirements in this General Permit. As mentioned above, this TMDL associates bed toxicity with discharges of metals, OC pesticides, PAHs, and PCBs bound to sediment particulates. Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment control, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
4) Dominguez Channel Estuary and Greater Harbor Waters Final Water-Column Waste Load Allocations
This TMDL assigns concentration-based final waste load allocations for the metals and organic compounds identified in Table 57 and Table 58 below. The waste load allocations are to be met in the water column for discharges to Dominguez Channel Estuary and the Greater Harbor Waters. Greater Harbor Waters include Inner and ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-209
Outer Harbor, Main Channel, Consolidated Slip, Southwest Slip, Fish Harbor, Cabrillo Marina, Inner Cabrillo Beach, Los Angeles River Estuary, and San Pedro Bay. The concentration-based waste load allocations are translated to numeric action levels because the waste load allocations are assigned to be met in the receiving waters and not at the point of discharge. The assigned waste load allocations of copper, lead, and zinc are based on the Criteria Chronic Concentration, and are inappropriate to assign to stormwater discharges. Therefore, the California Toxics Rule (CTR) Criterion Maximum (acute) Concentration is applied to Responsible Dischargers. The units are converted from ug/L to mg/L to be consistent with the reporting units in SMARTS. The numeric action levels assigned to Responsible Dischargers are shown in Table 59 and Table 60 below.

Table 59 – Dominguez Channel Estuary Final Water Column Waste Load Allocation Translations
Pollutant
Waste
Load
Allocation
(ug/L)
Dissolved Saltwater
Criterion Maximum
Concentration
(ug/L)
Total Saltwater
Criterion Maximum
Concentration
(ug/L)
Numeric
Action Level
(mg/L)
4,4-DDT 0.00059 5.9 X10-7
Chlordane 0.00059 5.9 X10-7
Dieldrin 0.00014 1.4 X10-7
Total Copper 3.73 4.8 5.8** 0.0058
Total Lead 8.53 210 221** 0.221
PAHs 0.049 4.9 X10-5
Total PCBs 0.00017 1.7 X10-7
Total Zinc 85.6 90 95** 0.095
* CTR human health criteria were not established for total PAHs. Therefore, the CTR criterion for individual PAHs of 0.049 μg/L is applied individually to benzo(a)anthracene, benzo(a)pyrene, and chrysene. The CTR criterion for Pyrene of 11,000 μg/L is assigned as an individual waste load allocation to Pyrene. Other PAH compounds in the CTR shall be screened as part of the TMDL monitoring.
**Values were rounded to match Criterion significant figures.

Table 60 – Greater Harbor Final Water Column Waste Load Allocation Translations
Pollutant
Waste
Load
Allocation
(ug/L)
Dissolved Saltwater
Criterion Maximum
Concentration
(ug/L)
Total Saltwater
Criterion Maximum
Concentration
(ug/L)
Numeric
Action Level
(mg/L)
4,4-DDT 0.00059 5.9 X10-7
Total Copper 3.73 4.8 5.8** 0.0058
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-210
Pollutant
Waste
Load
Allocation
(ug/L)
Dissolved Saltwater
Criterion Maximum
Concentration
(ug/L)
Total Saltwater
Criterion Maximum
Concentration
(ug/L)
Numeric
Action Level
(mg/L)
Total Lead 8.53 210 221** 0.221
Total PCBs 0.00017 1.7 X10-7
Total Zinc 85.6 90 95** 0.095
**Values were rounded to match Criterion significant figures. 5) Dominguez Chanel Estuary, Consolidated Slip, and Fish Harbor Final Sediment Waste Load Allocations
This TMDL assigns concentration-based final sediment waste load allocations for cadmium, chromium, and mercury to be met at the construction site’s discharge point(s) for discharges into Consolidated Slip and Fish Harbor, cadmium discharges into Dominguez Channel Estuary and Consolidated Slip, and chromium discharges into Consolidated Slip.

Table 61 – Dominguez Channel Estuary, Consolidated Slip and Fish Harbor Final Sediment Waste Load Allocations
Pollutant Waste Load Allocation (mg/kg sediment)
Cadmium* 1.2
Chromium** 81
Mercury*** 0.15
* Applies to Dominguez Channel Estuary and Consolidated Slip ** Applies to Consolidated Slip
*** Applies to Consolidated Slip and Fish Harbor
Directly implementing the final waste load allocations would be impractical, costly, and not aligned with the monitoring requirements in this General Permit. As mentioned above, this TMDL associates bed toxicity with discharges of metals bound to sediment particulates.

Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment control, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that discharge into the ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-211
Dominguez Channel or the Torrance Lateral, and identify on-site sources of copper, lead, and zinc through the required pollutant source assessment, shall compare all non-visible sampling and analytical results to the applicable interim numeric action levels for the metals.

Responsible Dischargers that discharge into the Dominguez Channel Estuary or the Greater Harbor waters, and that identify on-site sources of the metals and toxic pollutants listed in Table 60 and Table 61 are to implement BMPs specific to preventing or controlling stormwater contact with those metals and toxic pollutants. Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2, in order to address applicable interim sediment-based waste load allocations.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the interim numeric action levels and TSS numeric effluent limitations in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to the metals and toxic pollutant sources are expected to meet the assigned numeric action levels and TSS numeric effluent limitations.

The effective date of the TMDL, March 23, 2012, is the interim compliance deadline. Since this compliance deadline has passed, the requirements to meet the interim numeric action levels shall be met by the effective date of this General Permit. Responsible Dischargers are to comply with the final numeric action levels and TSS numeric effluent limitations by March 23, 2032, the final compliance deadline for the Los Angeles and Long Beach Harbor. Future reissuances of this General Permit may incorporate additional or revised compliance requirements or interim targets to progress towards the required final compliance when a final numeric action level or TSS numeric effluent limitation applies.
viii. Los Angeles River Metals TMDL273
The Los Angeles Regional Water Quality Control Board adopted the Los Angeles River Metals TMDL on April 9, 2015, to address the impairment of 273 Los Angeles Regional Water Quality Control Board, Amendment to the Water Quality Control Plan for the Los Angeles Region to Revise the Los Angeles River and Tributaries Metals TMDL (April 2015)
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R15- 004_BPA_CH_7.pdf> [as of May 20, 2021] (Los Angeles River Metals TMDL) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-212
Los Angeles River and its tributaries due to cadmium, copper, lead, selenium, and zinc.
· Source Analysis
Dry weather loading from storm drains contributes a large percentage of the loading because of low flows but high concentration of dissolved metals. During wet weather most metals loadings are in the particulate form where stormwater flows contribute a large percentage of cadmium, copper, lead, and zinc loading. Studies are underway to evaluate whether selenium levels represent a “natural condition” for this watershed.274
· Waste Load Allocation Translation
1) Dry-weather Waste Load Allocations
The Los Angeles River Metals TMDL assigns concentration-based waste load allocations for dry-weather. Non-Stormwater Discharges (NSWDs) are only authorized in this General Permit if the terms and conditions in Order, Section IV.A are met to control the discharge of pollutants from the construction site. Order, Section IV.B prohibits all NSWDs not authorized under Order, Section IV.A; therefore, all unauthorized NSWDs must be either eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this General Permit, are authorized because these discharges do not commingle with stormwater associated with construction activity. The Regional Water Board may impose additional requirements on NSWDs if deemed necessary per site- specific analysis.
2) Wet-weather Waste Load Allocations
The Los Angeles River Metals TMDL assigns a mass-based waste load allocation per construction area in grams per day per acre (g/d/ac) for cadmium, copper, lead, and zinc at the construction site’s discharge point(s) for discharges into the Los Angeles River or tributaries (Los Angeles River Watershed).275 In addition, daily storm volume flows are required to calculate the waste load allocation for each metal. The waste load allocations are shown in Table 62 below.

Directly implementing the copper, lead, and zinc waste load allocations would result in a unique mass load for each Responsible Discharger depended on the daily stormwater flows and the 274 Los Angeles River Metals TMDL, p. 4.
275 Los Angeles River Metals TMDL, p. 13.

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NPDES No. CAS000002
FACT SHEET FS-213
construction site’s acreage. Requiring Responsible Dischargers to calculate the site-specific mass load of a pollutant would be impractical, costly, and not aligned with the monitoring requirements in this General Permit.

The Los Angeles River Metals TMDL Staff Report allows for compliance to be assessed based on concentration. Additionally, the TMDL Staff Report states, “the wet-weather mass-based waste load allocations for the general construction and industrial stormwater permittees (Table 6-12) will be incorporated into watershed specific general permits. Concentration-based permit conditions may be set to achieve the mass-based waste load allocations. These concentration-based conditions would be equal to the concentration- based waste load allocations assigned to the other NPDES permits.” This TMDL states “each general construction stormwater permit holder will be subject to site-specific BMPs and monitoring requirements to demonstrate compliance with the final waste load allocations.”276 Therefore, it is consistent with the requirements and assumptions of the waste load allocation to apply the Los Angeles River Metals TMDL Numeric Targets as concentration-based numeric action levels (permit conditions).

The numeric action level iterative process in this General Permit requires dischargers to implement and evaluate performance of site- specific BMPs to demonstrate compliance with applicable waste load allocations. The units are converted from ug/L to mg/L to be consistent with the reporting units in SMARTS. The translated numeric action levels are shown in Table 62 below and a WER of

3.97 is used for copper.
276 Los Angeles River Metals TMDL, p. 23.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-214
Table 62 – Los Angeles River Waste Load Allocations Translation for Total Recoverable Metals
Pollutant Waste Load Allocation
(g/d/ac)
Numeric Target
(ug/L)
Numeric Action Level
(mg/L)
Cadmium* WER x (7.6 x 10-12) x daily
volume (L) – (4.8 x 10-6) WER x 3.1 0.0031
Copper** WER x (4.2 x 10-11) x daily
volume (L) – (2.6 x 10-5) WER x 17 0.06749
Lead* WER x (4.2 x 10-11) x daily
volume (L) – (8.7 x 10-5) WER x 94 0.094
Zinc* WER x (3.9 x 10-10) x daily
volume (L) – (2.2 x 10-4) WER x 159 0.159
* WER(s) have a default value of 1.0 unless site-specific WER(s) are approved. **The WER for this constituent is 3.97.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that discharge into the Los Angeles River or its tributaries, and that identify on-site sources of cadmium, copper, lead, and/or zinc through the required pollutant source assessment, shall compare all non-visible sampling and analytical results to the applicable numeric action levels for the identified metals.

Responsible Dischargers shall install, operate, and maintain site-specific BMPs to address identified on-site sources of cadmium, copper, lead, and/or zinc.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to the sources of metals are expected to meet the numeric action levels.

The final compliance deadline for the Los Angeles River Metals TMDL was January 11, 2016. Since this compliance deadline has passed, the numeric action levels are applicable upon the effective date of this General Permit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-215
ix. Los Cerritos Channel Metals TMDL277
The U.S. EPA adopted the Los Cerritos Metals TMDL on March 17, 2010, to address the impairment of Los Cerritos Channel due to copper, lead, and zinc.
· Source Analysis
Sources of metals from construction sites include sediment-bound metals, construction materials, and equipment used on construction sites. Additionally, in highly urbanized Los Cerritos Channel freshwater watershed, re-development of former industrial sites has a higher potential to discharge sediments laden with metals. During wet-weather, runoff from construction sites has the potential to contribute metals loadings to the Channel. Building materials and construction waste exposed to stormwater can leach and contribute metals to waterways.278 Therefore, construction sites covered under this General Permit are considered Responsible Dischargers for the Los Cerritos Channel Metals TMDL.
· Waste Load Allocation Translation
1) Dry-weather Waste Load Allocation
The Los Cerritos Channel Metals TMDL assigns a concentration- based waste load allocation for dry-weather. Non-Stormwater Discharges (NSWDs) are authorized in this General Permit if Order, Section IV.A terms and conditions are met to control the discharge of pollutants from the construction site. Order, Section IV.B prohibits all NSWDs not authorized under Order, Section IV.A; therefore, all unauthorized NSWDs must be either eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this General Permit, are authorized because these discharges do not commingle with stormwater associated with construction activity. The Regional Water Board may impose additional requirements on NSWDs if deemed necessary per site- specific analysis.
277 U.S. Environmental Protection Agency Region IX, Los Cerritos Channel Total Maximum Daily Loads for Metals (March 2010)
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Los%20Cerritos%20Channel%20Metals%20TMDL/03-18-10LosCerritosChannel- metalsTMDLs.pdf> [as of April 28, 2022]
278 Los Cerritos Channel Metals TMDL, p. 20.

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2) Wet-weather Waste Load Allocations
The Los Cerritos Channel Metals TMDL assigns a mass-based waste load allocation per construction area in grams per day per acre (g/day/ac) for copper, lead, and zinc for discharges into the Los Cerritos Channel. In addition, daily storm volume flows are required to calculate the waste load allocation for each metal. The mass- based waste load allocations are shown in Table 63 below.

Table 63 – Los Cerritos Mass-based Waste Load Allocations Pollutant Waste Load Allocation (g/day/ac)
Copper 0.497 x 10-3 x daily volume(L)
Lead 2.835 x 10-3 x daily volume(L)
Zinc 4.860 x 10-3 x daily volume(L)
Directly implementing the copper, lead, and zinc mass-based waste load allocations would result in a unique mass load for each Responsible Discharger, dependent on the daily stormwater flows and the construction site’s acreage. Requiring Responsible Dischargers to calculate the site-specific mass loading of a pollutant(s) is impractical, costly, and not aligned with the monitoring requirements of this this General Permit. The Los Cerritos Channel TMDL Implementation Plan279 requires incorporation of the waste load allocations in this General Permit as wet-weather permit limitations expressed as event mean concentrations.

The term permit limitation in the TMDL implementation plan is defined as “a water-quality based effluent limitation or a receiving water limitation…permittees may demonstrate compliance with wet - weather waste load allocations in any one of three ways. First, general industrial and construction storm water permittees may be deemed in compliance with permit limitations if they demonstrate that there are no exceedances of the permit limitations at their discharge points or outfalls. Second, general industrial and construction storm water permittees may be deemed in compliance with permit limitations if they demonstrate that there are no exceedances of the permit limitations in the receiving water at, or downstream of, the 279 Los Angeles Regional Water Quality Control Board, Amendment to the Water Quality Control Plan – Los Angeles Region to Incorporate the Implementation Plan for the Total Maximum Daily Loads for Metals in the Los Cerritos Channel <https://www.waterboards.ca.gov/losangeles/board_decisions/basin_plan_amendmen ts/technical_documents/99_New/Los%20Cerritos%20Metals%20implementation%20p lan%20and%20schedule%20BPA_rev%20053013.pdf> [as of April 28, 2022] (Los Cerritos Channel Metals TMDL Implementation Plan)
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permittee's outfalls. Third, if permittees provide a quantitative demonstration that control measures and best management practices (BMPs) will achieve wet-weather waste load allocations consistent with the schedule in Table 7-20.2, then compliance may be demonstrated by implementation of those control measures and BMPs, subject to Executive Officer approval.”280 The assigned mass- based waste load allocations require site-specific calculations that are incompatible with the monitoring and reporting requirements in this General Permit. Therefore, it is consistent with the requirements and assumptions of the waste load allocations to implement the Los Cerritos Channel Metals TMDL Numeric Targets as concentration- based numeric action levels to align the mass-based waste load allocations to the requirements in this General Permit. The TMDL implementation plan provided Responsible Dischargers the above- stated three options for demonstrating waste load allocation compliance. The option implemented in this General Order is to implement the TMDL-specific numeric action levels at the point of discharge for the Responsible Discharger’s construction site. The assigned concentration based numeric action levels are shown in Table 64 below. The units are converted from ug/L to mg/L to be consistent with the reporting units in SMARTS.

Table 64 – Los Cerritos Channel Waste Load Allocations (Concentration-based, Total Recoverable)
Pollutant Numeric Targets (ug/L) Numeric Action Levels (mg/L) Copper 9.8 0.0098
Lead 55.8 0.0558
Zinc 95.6 0.0956
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that discharge into the Los Cerritos Channel and that identify on-site sources of copper, lead, and zinc through the required pollutant source assessment, shall compare all non-visible sampling and analytical results to the applicable numeric action levels for the identified metals.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible 280 Los Cerritos Channel Metals TMDL Implementation Plan, p. 4-5.

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Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to the metals’ sources are expected to meet the assigned numeric action levels.

The TMDL’s final compliance deadline was September 30, 2017. Since this compliance deadline has passed, the numeric action levels are applicable upon the effective date of this General Permit. x. Machado Lake Toxics TMDL281
The Los Angeles Regional Water Quality Control Board adopted the Machado Lake Toxics TMDL on September 2, 2010, to address the impairment of Machado Lake due to chemical group organochlorine (OC) pesticides (chlordane, DDT, dieldrin) and polychlorinated biphenyls (PCBs). · Source Analysis
The point sources of OC pesticides and PCBs into Machado Lake are stormwater and urban runoff discharges from the municipal separate storm sewer system (MS4), the California Department of Transportation, and general construction and industrial dischargers. Therefore, construction sites covered under this General Permit are considered Responsible Dischargers for the Machado Lake Toxics TMDL.

OC pesticides are no longer legally sold or used, but remain ubiquitous in the environment, bound to fine-grained particles. The chemicals are transported to new locations when these particles become waterborne.

The more recent small discharges of OC pesticides and PCBs to Machado Lake most likely come from the erosion of pollutant-laden sediment further up in the watershed. Urban runoff and rainfall higher in the watershed mobilize the particles, which are then washed into storm drains and channels that discharge to the lake. Stormwater and urban runoff discharges to Machado Lake occur through the Wilmington Drain, Project 77, and Project 510 subdrainage systems. The estimated contributions of OC pesticides and PCBs from point sources is much smaller than the estimated contribution from internal lake sediments.

However, a waste load allocation is assigned to ongoing point source discharges to the lake.
281 Los Angeles Regional Water Quality Control Board, Machado Lake Pesticides and PCBs TMDL (September 2, 2010),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R10- 008_RB_BPA.pdf> [as of May 20, 2021] (Machado Lake Toxics TMDL) ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-219
· Waste Load Allocation Translation
The Machado Lake Toxics TMDL assigns a suspended sediment concentration-based waste load allocations for OC pesticides and PCBs to be met at the construction site’s discharge location(s) for discharges into Machado Lake, shown in Table 65 below.

Table 65 – Machado Lake Toxics Waste Load Allocations
Pollutant Waste Load Allocation of Suspended Sediment-
Associated Contaminants (ug/kg dry weight)
Chlordane 3.24
DDD (all congeners) 4.88
DDE (all congeners) 3.16
DDT (all congeners) 4.16
Dieldrin 1.9
Total DDTs 5.28
Total PCBs 59.8
Requiring Responsible Dischargers to directly implement the waste load allocation and sample for the pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most toxic pollutants loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the toxic pollutants associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the toxic pollutants.

Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The Machado Lake Toxics TMDL’s final compliance deadline was September 30, 2019. Since this compliance deadline has passed, ORDER WQ 2022-0057-DWQ
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FACT SHEET FS-220
compliance with the waste load allocations shall be met upon the effective date of this General Permit.
xi. Marina del Rey Toxics TMDL282
The Los Angeles Regional Water Quality Control Board adopted the Marina del Rey Toxics TMDL on February 6, 2014, to address the impairment of Marina del Rey Harbor due to chlordane, copper, DDT, dieldrin, fish consumption advisory, lead, polychlorinated biphenyls (PCBs), sediment toxicity, and zinc. During the development of this TMDL, review of available data indicated that dieldrin is no longer a cause of impairment, and that there is a dissolved copper impairment in the water column and sediment. · Source Analysis
Urban stormwater has been recognized as a substantial source of metals. Numerous researchers have documented that the most prevalent metals in urban stormwater (i.e., copper, lead, and zinc) are consistently associated with suspended solids. Because metals are typically associated with fine particles in stormwater runoff, they have the potential to accumulate in marine sediments where they may pose a toxicity risk. A majority of organic constituents in stormwater are also associated with particulates. Once the particles accumulate in the sediments in the harbor, the sediments themselves can become a source through re-suspension and are thus assigned load allocations.

Therefore, construction sites covered under this General Permit are considered Responsible Dischargers for the Marina del Rey Toxics TMDL.

In addition to stormwater runoff, copper-based anti-fouling paints are recognized as substantial sources of dissolved copper in the water column and sediments. Site-specific modeling indicated that 100 percent of copper loading came from copper-based anti-fouling hull paint and hull cleaning activities. Direct deposition of airborne particles to the water surface may be a minor source responsible for contributing metals and organic pollutants to the Marina del Rey Harbor.283
282 Los Angeles Regional Water Quality Control Board, Amendment to the Water Quality Control Plan – Los Angeles Region to incorporate the Marina del Rey Harbor Toxic Pollutants TMDL (February 6, 2014),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R14- 004_RB_BPA.pdf> [as of May 20, 2021] (Marina del Rey Harbor Toxics TMDL) 283 Marina del Rey Harbor Toxics TMDL, p. 3-4.

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FACT SHEET FS-221
· Waste Load Allocation Translation
The Marina del Rey Toxics TMDL assigns a mass-based waste load allocation per construction area in grams per day per acre (g/day/ac) or milligrams per day per acre (mg/day/ac) for chlordane, copper, total DDTs, Dichlorodiphenyldichloroethylene (p,p’-DDE), lead, total PCBs, and zinc for discharges into the Marina del Rey Harbor. The mass-based waste load allocations are shown in Table 66 and Table 67 below.

Table 66 – Marina del Rey Toxics Metals Waste Load Allocations Pollutant Waste Load Allocation (g/yr/ac)
Copper 1.9
Lead 2.6
Zinc 8.5
Table 67 – Marina del Rey Toxics OC Pesticides Waste Load Allocations Pollutant Waste Load Allocation (mg/yr/ac)
Chlordane 0.03
Total PCBs 1.3
Total DDTs 0.09
p,p’-DDE 0.12
Requiring Responsible Dischargers to directly implement the waste load allocation and sample for the pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most toxic pollutants loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
100 percent of the copper loadings into the Marina del Rey Harbor comes from the leaching of antifouling hull paint and from hull cleaning operations. Therefore, the copper numeric target will not be assigned to Responsible Dischargers and compliance with this waste load allocation shall be through compliance with this General Permit.

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· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the metals and toxic pollutants associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the metals and toxic pollutants. Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The Marina del Rey Toxics TMDL’s final compliance deadline was March 22, 2016. Since this compliance deadline has passed, the waste load allocations shall be met upon the effective date of this General Permit. xii. Oxnard Drain No. 3 Toxics TMDL284
The U.S. EPA adopted the Oxnard Drain No. 3 Toxics TMDL on October 6, 2011, to address the impairment of the Oxnard Drain No. 3 due to bifenthrin, chlorpyrifos, organochlorine (OC) pesticides (chlordane, DDT, dieldrin, and toxaphene), polychlorinated biphenyls, and sediment toxicity. · Source Analysis
The Oxnard Drain No. 3 Toxics TMDL identifies historic and current loadings of toxic pollutants, including construction sites that would be covered under this General Permit. During wet weather, discharges from construction sites have the potential to contribute toxic pollutant loadings. However, dry weather discharges have less potential to contribute to toxic pollutant loadings as non-stormwater discharges authorized by this General Permit are only authorized when they do not cause or contribute to a violation of any water quality standard.

Therefore, construction sites covered under this General Permit are considered Responsible Dischargers for the Oxnard Drain No. 3 Toxics TMDL.
· Waste Load Allocation Translation
The Oxnard Drain No. 3 Toxics TMDL assigns a concentration-based waste load allocation to construction stormwater discharges for 4,4’- 284 United States EPA Region IX, Total Maximum Daily Loads for Pesticides, PCBs, and Sediment Toxicity in Oxnard Drain No.3 (October 6, 2011), <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /Oxnard%20Drain%20No.%203%20Pesticides%20PCBs%20and%20Sediment%20T oxicity%20TMDL/oxnard-drain-3-tmdl-10-2011.pdf> [as of April 28, 2022] (Oxnard Drain No. 3 Toxics TMDL)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
FACT SHEET FS-223
DDD, 4,4’-DDE, 4,4’-DDT, bifenthrin, chlorpyrifos, dieldrin, total chlordane, total PCBs, and toxaphene expressed as water, bed sediment and suspended sediment concentrations in ug/kg to be met at the construction site’s discharge location(s) for discharges into the Oxnard Drain No. 3. OC pesticides and PCBs have an affinity for organic matter and will partition from water to organic substances such as sediment, benthic organisms, and fish, so the sediment allocations are applied, shown in Table 68 below.

Table 68 – Oxnard Drain No. 3 Waste Load Allocations
Pollutant Waste Load Allocation of Suspended Sediment-
Associated Contaminants (ug/kg dry weight)
4,4’-DDD 2.0
4,4’-DDE 2.2
4,4’-DDT 0.3
Bifenthrin -
Chlordane, Total 3.3
Chlorpyrifos -
Dieldrin 4.3
PCBs, Total 180
Sediment Toxicity -
Toxaphene 360
Requiring Responsible Dischargers to directly implement the waste load allocation and sample for the pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most toxic pollutants loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the toxic pollutants associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the toxic pollutants.

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Furthermore, Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The Los Angeles Regional Water Quality Control Board has not adopted an Implementation Plan or a compliance schedule for the toxic pollutants addressed by the Oxnard Drain No. 3 Toxics TMDL. Therefore, Responsible Dischargers are required to achieve compliance with the waste load allocations upon the effective date of this General Permit. xiii. San Gabriel River Metals and Selenium TMDL285
The U.S. EPA adopted the San Gabriel River Metals TMDL on March 26, 2007, to address the impairment of San Gabriel River, estuary, and tributaries due to copper, lead, selenium, and zinc. A TMDL was not developed for the elevated levels of selenium in Reach 6 during dry weather conditions because the sources of selenium appear to be related to natural levels of selenium in the soils.
· Source Analysis
Sources of metals from construction sites include sediment-bound metals, construction materials, and equipment used on construction sites. Building materials and construction waste exposed to stormwater can leach and contribute metals to waterways. During dry weather, the potential contribution of metals loading from Responsible Dischargers is low.286
· Waste Load Allocation Translation
1) Dry-weather Waste Load Allocation
The San Gabriel River Metals TMDL assigns concentration-based and mass-based waste load allocations for dry-weather discharges of copper and selenium. Non-Stormwater Discharges (NSWDs) are authorized in this General Permit if Order, Section IV.A terms and conditions are met to control the discharge of pollutants from the construction site. Order, Section IV.B prohibits all NSWDs not authorized under Order, Section IV.A; therefore, all unauthorized NSWDs must be either eliminated or have regulatory coverage under a separate NPDES permit. Authorized NSWDs, as defined in this 285 U.S. Environmental Protection Agency Region IX, Total Maximum Daily Loads for Metals and Selenium San Gabriel River and Impaired Tributaries (March 26, 2007) <https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /San%20Gabriel%20River%20Metals%20TMDL/final_sangabriel_metalstmdl_3-27-

07.pdf> [as of May 20, 2021] (San Gabriel River Metals TMDL) 286 San Gabriel River Metals TMDL, p. 22.

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General Permit, are authorized because these discharges do not commingle with stormwater associated with construction activity. The Regional Water Board may impose additional requirements on NSWDs if deemed necessary per site-specific analysis.
2) Wet-weather Waste Load Allocations
The San Gabriel River Metals TMDL assigns a mass-based waste load allocation per construction area in kilograms per day (kg/d) for lead for discharges into the San Gabriel River Reach 2 watershed (all upstream reaches and tributaries) and Coyote Creek or its tributaries.

The waste load allocations are shown in Table 69 and Table 70 below.

Table 69 – San Gabriel River Reach 2 Watershed Waste Load Allocation Pollutant Waste Load Allocation (kg/d)
Lead 0.8
Table 70 – Coyote Creek Watershed Waste Load Allocations Pollutant Waste Load Allocation (kg/d)
Copper 0.513
Lead 2.07
Zinc 3.0
The San Gabriel River Metals TMDL Implementation Plan287 requires incorporation of the waste load allocations in this General Permit as permit limitations expressed as event mean concentrations. The term permit limitation is defined in the TMDL compliance plan as “a water- quality based effluent limitation or a receiving water
limitation…permittees may demonstrate compliance with wet -weather waste load allocations in any one of three ways. First, general industrial and construction storm water permittees may be deemed in compliance with permit limitations if they demonstrate that there are no exceedances of the permit limitations at their discharge points or outfalls. Second, general industrial and construction storm water permittees may be deemed in compliance with permit limitations if they demonstrate that there are no exceedances of the permit 287 Los Angeles Regional Water Quality Control Board, Amendment to the Water Quality Control Plan – Los Angeles Region to Incorporate the Implementation Plan for the Total Maximum Daily Loads for Metals and Selenium in the San Gabriel River and Impaired Tributaries (June 6, 2013)
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/docs/R13- 004_RB_BPA.pdf> [as of May 20, 2021] (San Gabriel River Metals TMDL Implementation Plan)
ORDER WQ 2022-0057-DWQ
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limitations in the receiving water at, or downstream of, the permittee's outfalls. Third, if permittees provide a quantitative demonstration that control measures and best management practices (BMPs) will achieve wet-weather waste load allocations consistent with the schedule in Table 7-20.2, then compliance may be demonstrated by implementation of those control measures and BMPs, subject to Executive Officer approval.”288
The assigned mass-based waste load allocations require site-specific calculations that are incompatible with the monitoring and reporting requirements in this General Permit. Therefore, it is consistent with the requirements and assumptions of the waste load allocations to implement the San Gabriel River Metals and Selenium TMDL Numeric Targets as concentration-based numeric action levels to align the mass-based waste load allocations to the requirements in this General Permit. The TMDL implementation plan provided Responsible Dischargers the three above-stated options for demonstrating waste load allocation compliance and the appropriate option is to implement the TMDL-specific numeric action levels at the point of discharge for the Responsible Discharger’s construction site.

The assigned concentration-based numeric action levels are shown in Table 71 and Table 72 below. The units are converted from ug/L to mg/L to be consistent with the reporting units in SMARTS.

Table 71 – San Gabriel River Reach 2 Watershed Waste Load Allocation Translation (concentration-based, total recoverable)
Pollutant Numeric Targets (ug/L) Numeric Action Levels (mg/L) Lead 166 0.166
Table 72 – Coyote Creek Watershed Waste Load Allocations (concentration- based, total recoverable)
Pollutant Numeric Targets (ug/L) Numeric Action Levels (mg/L) Copper 27 0.027
Lead 106 0.106
Zinc 158 0.158
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that discharge into the San Gabriel River and that identify on-site sources of copper, lead, and zinc through the required pollutant source assessment, shall compare all 288 San Gabriel River Metals TMDL Implementation Plan, p. 4-5.

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non-visible sampling and analytical results to the applicable numeric action levels for the identified metals.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to the metals sources are expected to meet the numeric action levels.

The San Gabriel River Metals TMDL’s final compliance deadline was September 30, 2017. Since this compliance deadline has passed, the numeric action levels are applicable upon the effective date of this General Permit.
xiv. Santa Monica Bay Toxics TMDL289
The U.S. EPA adopted the Santa Monica Bay Toxics TMDL on March 26, 2012, to address the impairment for Santa Monica Bay due to DDTs and polychlorinated biphenyls (PCBs). Santa Monica Bay, as defined in this TMDL, is Point Dume to Point Vicente and the Palos Verdes shelf from Point Vicente to Point Fermin.
· Source Analysis
DDTs are organochlorine insecticides widely used in the past on agricultural crops and to control disease-carrying insects. The United States banned the use of DDTs in 1972, except for public health emergencies involving insect diseases and control of body lice. Although use of DDTs is limited, it can persist in the environment, adhering strongly to soil particles. PCBs are mixtures of up to 209 individual chlorinated compounds (known as congeners). In 1976, the manufacturing of PCBs was prohibited because of evidence that they build up in the environment and can cause harmful health effects. Similar to DDTs, PCBs adhere to soil and can be transported into watersheds via erosion and stormwater runoff. Studies within the watershed indicated that concentrations of DDTs and PCBs in stormwater may exceed human health criteria. Therefore, construction sites covered 289 U.S. Environmental Protection Agency Region IX, Santa Monica Bay Total Maximum Daily Loads for DDTs and PCBs (March 26, 2012),
<https://www.waterboards.ca.gov/losangeles/water_issues/programs/tmdl/Established /SantaMonica/FinalSantaMonicaBayDDTPCBsTMDL.pdf> [as of May 20, 2021] (Santa Monica Bay Toxics TMDL)
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FACT SHEET FS-228
under this General Permit are considered Responsible Dischargers for the Santa Monica Bay Toxics TMDL.
· Waste Load Allocation Translation
The Santa Monica Bay Toxics TMDL assigns mass-based waste load allocations of 0.16 g/yr for DDT and 0.82 g/yr for PCBs to be met at the construction site’s discharge location(s) for discharges into Santa Monica Bay. The waste load allocations are based on the aggregate area represented by individual permittees covered under this General Permit, which is roughly 0.56 percent of the watershed’s total area.

Table 73 shows the waste load allocation below.

Table 73 – Santa Monica Bay Toxics Waste Load Allocations Pollutant Waste Load Allocation (g/yr)
DDTs 0.16
PCBs 0.82
Permittees covered under this General Permit are not expected to perform individual sampling. Requiring Responsible Dischargers to directly implement the waste load allocation and sample for the pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most toxic pollutants loadings in this watershed are in particulate form and associated with wet-weather flows. Therefore, the following will address this TMDL:
1) Comply with the site-specific erosion and sediment control, and post- construction requirements in this General Permit.
2) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre- construction (e.g., undisturbed vegetation for the area) conditions.

Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.
· Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of the toxic pollutants associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the toxic pollutants.

Furthermore, Responsible Dischargers are to comply with the RUSLE 2 modeling requirements in Attachment H, Section I.G.2.

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FACT SHEET FS-229
The Los Angeles Regional Water Quality Control Board has not adopted an Implementation Plan or a compliance schedule for the toxic pollutants addressed by the Santa Monica Bay Toxics TMDL. Therefore, Responsible Dischargers are required to achieve compliance with the waste load allocations upon the effective date of this General Permit. xv. San Diego Creek and Newport Bay Toxics TMDL 290,291 The U.S. EPA adopted the San Diego Creek and Newport Bay Toxics TMDL on June 14, 2002, to address the impairments of San Diego Creek and Newport Bay due to cadmium, chlordane, chlorpyrifos, chromium, copper, DDT, diazinon, dieldrin, lead, mercury, polychlorinated biphenyls (PCBs), selenium, toxaphene, and zinc. However, the Santa Ana Regional Water Quality Control Board adopted a separate Revised Organochlorine Compounds (chlordane, DDT, dieldrin, PCBs, and toxaphene) TMDL on July 15, 2011, which revises the loading capacities in the U.S. EPA TMDL based on an updated impairment assessment. For the purpose of this General Permit and factsheet, both TMDLs will be addressed as a single San Diego Creek and Newport Bay Toxics TMDL.
· Source Analysis
The San Diego Creek and Newport Bay Toxics TMDL provides source analyses specific to the pollutant categories: metals, organochlorine compounds, chromium, and mercury. These pollutants are known to adsorb or adhere to sediment which are transported through the watershed via soil erosion and runoff. Surface runoff from natural background and man-made contributions are estimated to be the largest source of metals within San Diego Creek and its tributaries. The largest source of dissolved metals (except copper) to Upper and Lower Newport Bay are thought to be freshwater-borne loads from San Diego Creek.

Likewise, the main source of continual loadings of organochlorine pollutants to the Newport Bay watershed is also attributed to erosion of 290 United States EPA, Total Maximum Daily Loads for Toxic Pollutants San Diego Creek and Newport Bay, California (June 14, 2002),
<https://www.waterboards.ca.gov/santaana/water_issues/programs/tmdl/docs/sd_crk_ nb_toxics_tmdl/summary0602.pdf> [as of May 20, 2021] (San Diego Creek and Newport Bay Toxics TMDL)
291 Santa Ana Regional Water Quality Control Board, Revised Organochlorine Compounds TMDLs for San Diego Creek, Upper and Lower Newport Bay (July 15, 2015),
<https://www.waterboards.ca.gov/rwqcb8/water_issues/programs/tmdl/docs/oc/2011- 0037/FINAL/R8-2011-0037_Attachment2_Final_BPA.PDF> [as of May 20, 2021] (San Diego Creek and Newport Bay Toxics TMDL)
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surface soils or in-stream sediments, primarily from San Diego Creek.

Construction activities have the potential to exacerbate erosion within the watershed, therefore construction sites covered under this General Permit are considered Responsible Dischargers.

Chlorpyrifos, chromium, diazinon, dieldrin, mercury, and selenium are not translated for this General Permit as construction stormwater discharges are not identified as sources of these pollutants. · Waste Load Allocation Translation
The San Diego Creek and Newport Bay Toxics TMDL assigns waste load allocations for various metals (cadmium, copper, lead, and zinc) and organochlorine compounds (chlordane, DDT, PCBs, and toxaphene) to Responsible Dischargers to be met at the site’s discharge location(s) for dischargers into Newport Bay or San Diego Creek and its tributaries.

The following list details the water bodies and their associated pollutants with assigned waste load allocations:
1) San Diego Creek: cadmium, copper, lead, zinc, DDT, and toxaphene The San Diego Creek and Newport Bay Toxics TMDL assigns concentration-based waste load allocations for cadmium, copper, lead, and zinc to the category “Other NPDES permittees” which includes Responsible Dischargers in addition to seven other NPDES permits. The TMDL does not specifically identify construction stormwater dischargers as a major source of metals to the impaired waterbodies or divide the waste load allocations between permitted dischargers. Furthermore, the TMDL includes an option for the Water Boards to conduct a permit-specific analysis to divide the waste load allocations; however, conducting the analysis on a discharge flow, volume, and timing basis is not aligned with the framework of this General Permit.

The waste load allocations are assigned to Responsible Dischargers to be met at the construction site’s discharge location(s) for discharges into San Diego Creek and its tributaries including the Santa Ana-Delhi Channel, Big Canyon Channel, East Costa Mesa Channel, and other tributaries into San Diego Creek (San Diego Creek Watershed). Therefore, these waste load allocations are translated as concentration-based numeric action levels applied at the point(s) of discharge from the Responsible Discharger’s construction site. The waste load allocations are hardness dependent, meaning the receiving water body hardness must be known to calculate the waste load allocations.

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Receiving water body hardness is dependent on receiving water body flow. The U.S. EPA calculated the hardness-dependent criteria for cadmium, copper, lead, and zinc as shown in Table 5-2 of the San Diego Toxics TMDL with the following CTR equation:

CMC = WER X (Acute Conversion Factor) X
(exp{mA[ln (hardness)]+bA})
Where CMC stands for criterion maximum concentration, WER is the water effect ratio, and mA and bA are constants, specific to each metal. Hardness is defined as the concentration of calcium carbonate (CaCO3) in the water column and has the units of milligram per liter (mg/L). Freshwater aquatic life criteria for certain metals are expressed as a function of hardness because hardness and/or water quality characteristics that are usually correlated with hardness can reduce or increase the toxicity of some metals. The site-specific hardness is used to calculate the metal numeric targets.

Only one hardness value is selected to be representative of the receiving water body instead of requiring Responsible Dischargers to sample for receiving water body hardness in concurrence with taking a discharge sample to calculate the metal criteria. This is consistent with the approach taken in many hardness-dependent TMDLs of assigning a hardness value based on existing data. The U.S. EPA and the Santa Ana Regional Water Quality Control Board staff evaluated daily flow records of the San Diego Creek for 19 years.

The TMDL developed multiple receiving water hardness values based on flow and did not assign one hardness value to be representative of the San Diego Creek water body. A hardness of 197mg/L was calculated as the average hardness for large flows and is selected as the typical hardness value associated with a precipitation event flow at San Diego Creek. Table 5-2 of the San Diego Toxics TMDL shows how the California Toxics Rule (CTR) equation was used to calculate the acute concentration criteria at a hardness of 197 mg/L.

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Table 74 – San Diego Creek Watershed Waste Load Allocation Translation Parameter CTR Equation
Total Criteria
with 197
hardness in
mg/L
Total
freshwater
acute
concentration
Numeric Action
Level mg/L*
Cadmium (exp(1.128*ln(hardness)-3.6867)) 0.0097 0.0097
Copper (exp(0.9422*ln(hardness)-1.7)) 0.027 0.027
Lead (exp(1.273*ln(hardness)-1.460)) 0.194 0.194
Zinc (exp(0.8473*ln(hardness)+0.884)) 0.21 0.21
*Values are rounded to reflect the significant figures of each respective pollutant An average hardness of San Diego Creek was selected to calculate the criteria for translating each pollutant into a numeric action level in the San Diego Toxics TMDL because it is not feasible or practical to require Responsible Dischargers to collect the ambient hardness of the receiving water body in concurrence with each monitoring sample.

The Revised Organochlorine Compounds TMDL assigns mass- based waste load allocations for total DDT and toxaphene on an annual basis to Responsible Dischargers in the San Diego Creek watershed, shown in Table 76 below. Requiring Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most organochlorine compound loadings in this watershed are in the form of fine sediment transported through erosion. The TMDL’s implementation plan intends to use source control to reduce the loading of organochlorine compounds into the watershed, which is aligned with the requirements of this General Permit. Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment controls, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.

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2) Upper Newport Bay: cadmium, copper, lead, zinc, chlordane, DDT, and PCBs
Mass-based waste load allocations for dissolved cadmium, copper, lead, and zinc are assigned to be met in the receiving water of Upper Newport Bay. Concentration-based waste load allocations for cadmium, copper, lead, and zinc in Upper Newport Bay are assigned to Other NPDES Dischargers, which includes construction stormwater dischargers. However, the TMDL does not specifically identify construction stormwater dischargers as a major source of metals to the impaired waterbodies or divide the waste load allocations between permitted dischargers. The TMDL includes an option for the Water Boards to conduct a permit-specific analysis to dive the waste load allocations; however, conducting the analysis on a discharge flow, volume, and timing basis is not aligned with the framework of this General Permit. Therefore, these waste load allocations are translated as concentration-based numeric action levels applied to the point(s) of discharge from the Responsible Discharger’s construction site. The concentration-based waste load allocations are translated into total concentrations using the CTR conversion factor for saltwater acute criteria. The numeric action levels are shown in Table 75 below.

The Revised Organochlorine Compounds TMDL assigns mass- based waste load allocations for chlordane, DDT, and PCBs on an annual basis to Responsible Dischargers in Upper Newport Bay, shown in Table 76 below. Requiring Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most organochlorine compound loadings in this watershed are in the form of fine sediment transported through erosion. The TMDL’s implementation plan intends to use source control to reduce the loading of organochlorine compounds into the watershed, which is aligned with the requirements of this General Permit. Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment controls, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.

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3) Lower Newport Bay: copper, lead, zinc, chlordane, DDT, and PCBs Mass-based waste load allocations for dissolved copper, lead, and zinc are assigned to be met in the receiving water of Lower Newport Bay. Concentration-based waste load allocations for copper, lead, and zinc in Lower Newport Bay are assigned to Other NPDES Dischargers, which includes construction stormwater dischargers.

However, the TMDL does not specifically identify construction stormwater dischargers as a major source of metals to the impaired waterbodies or divide the waste load allocations between permitted dischargers. The TMDL includes an option for the Water Boards to conduct a permit-specific analysis to dive the waste load allocations; however, conducting the analysis on a discharge flow, volume, and timing basis is not aligned with the framework of this General Permit.

Therefore, these waste load allocations are translated as concentration-based numeric action levels applied to the point(s) of discharge from the Responsible Discharger’s construction site. The concentration-based waste load allocations are translated into total concentrations using the CTR conversion factor for saltwater acute criteria. The numeric action levels are shown in Table 75 below.

The Revised Organochlorine Compounds TMDL assigns mass- based waste load allocations for chlordane, DDT, and PCBs on an annual basis to Responsible Dischargers in Lower Newport Bay, shown in Table 76 below. Requiring Responsible Dischargers to calculate the construction site’s specific mass loading of a pollutant(s) would be impractical, costly, and not aligned with the requirements of this General Permit. However, as mentioned in the source analysis, most organochlorine compound loadings in this watershed are in the form of fine sediment transported through erosion. The TMDL’s implementation plan intends to use source control to reduce the loading of organochlorine compounds into the watershed, which is aligned with the requirements of this General Permit. Therefore, the following will address this TMDL:
a) Comply with the site-specific erosion and sediment controls, and post-construction requirements in this General Permit.
b) For each phase of the construction project, install erosion controls that will result in predicted erosion rates that are as protective as pre-construction (e.g., undisturbed vegetation for the area) conditions. Calculate the predicted erosion rates by using RUSLE2 modeling as described in Attachment H.

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4) Rhine Channel Area of Lower Newport Bay: copper, lead, and zinc Mass-based waste load allocations for dissolved, copper, lead, and zinc are assigned to be met in the receiving water of the Rhine Channel. Concentration-based waste load allocations for copper, lead, and zinc in Lower Newport Bay are assigned to Other NPDES Dischargers, which includes construction stormwater dischargers.

However, the TMDL does not specifically identify construction stormwater dischargers as a major source of metals to the impaired waterbodies or divide the waste load allocations between permitted dischargers. The TMDL includes an option for the Water Boards to conduct a permit-specific analysis to dive the waste load allocations; however, conducting the analysis on a discharge flow, volume, and timing basis is not aligned with the framework of this General Permit.

Therefore, these waste load allocations are translated as concentration-based numeric action levels applied to the point(s) of discharge from the Responsible Discharger’s construction site. The concentration-based waste load allocations are translated into total concentrations using the CTR conversion factor for saltwater acute criteria. The numeric action levels are shown in Table 75 below.

Table 75 – Upper Newport Bay, Lower Newport Bay and Bay Segments, and Rhine Channel Metals Waste Load Allocation Translation
Parameter
Dissolved
saltwater acute
TMDLs and
allocations (ug/L)
CTR Conversion
Factor for saltwater
acute criteria
Total saltwater acute
concentration
Numeric Action Level
(mg/L)
Cadmium* 42 0.994 0.042**
Copper 4.8 0.83 0.00578**
Lead 210 0.951 0.221**
Zinc 90 0.946 0.095**
*Applies to Upper Newport Bay only
**Values are rounded to reflect the significant figures of each respective pollutant Table 76 – San Diego Creek, Upper Newport Bay and Lower Newport Bay Organochlorine Compounds Waste Load Allocations
Parameter Total DDT
(g/yr)
Chlordane
(g/yr)
Total PCBs
(g/yr)
Toxaphene
(g/yr)
San Diego Creek 99.8 1.5
Upper Newport Bay 40.3 23.4 23.2
Lower Newport Bay 14.9 8.6 60.7
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· Compliance Actions and Schedule
1) Metals
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that discharge into San Diego Creek, Upper Newport Bay, Lower Newport Bay, or the Rhine Channel and that identify on-site sources of cadmium, copper, lead, and zinc through the required pollutant source assessment, shall compare all non-visible sampling and analytical results to the applicable numeric action levels for the identified metals.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric action levels in the future. Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to the metals’ sources are expected to meet the numeric action levels.

The Santa Ana Regional Water Quality Control Board has not adopted an Implementation Plan or a compliance schedule for the metals addressed by the San Diego Creek and Newport Bay Toxics TMDL. Therefore, Responsible Dischargers are required to achieve compliance with the translated numeric action levels by the effective date of this General Permit.
2) Organochlorine Compounds
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that identify on-site sources of organochlorine compounds associated with the impaired water body, through the required pollutant source assessment, are to implement BMPs specific to preventing or controlling stormwater exposure to the organochlorine compounds. Furthermore,
Responsible Dischargers are to comply with the RUSLE2 modeling requirements in Attachment H, Section I.G.2.

The Revised Organochlorine Compounds TMDL’s final compliance deadline for the TMDLs is December 31, 2020. Therefore, Responsible Dischargers shall comply with the requirements of this General Permit and the RUSLE2 modeling requirements in
Attachment H, Section I.G.2, upon the effective date of this General Permit.

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xvi. Chollas Creek Metals TMDL292
The San Diego Regional Water Quality Control Board adopted the Chollas Creek Metals TMDL on June 13, 2007, to address the impairment of Chollas Creek due to dissolved copper, lead, and zinc.
· Source Analysis
The major urban runoff contributors of copper, lead, and zinc into Chollas Creek include freeways, commercial, and industrial land uses.293 Construction erosion is a potential source of metals in Chollas Creek.294 Sediment is assumed to not reside in Chollas Creek long enough to allow metal concentrations to build to high enough levels that the sediment becomes a source to the creek.295 However, construction sites covered under this General Permit are identified as Responsible Dischargers for the Chollas Creek Metals TMDL.
· Waste Load Allocation Translation
The Chollas Creek Metals TMDL assigns waste load allocations for dissolved copper, lead, and zinc to Responsible Dischargers to be met at the construction discharge location(s).

The waste load allocations for dissolved copper, lead, and zinc are concentration-based and set equal to 90 percent of the numeric targets, which is the CTR acute criteria, shown in Table 77 below. 292 San Diego Regional Water Quality Control Board, A Resolution Adopting an Amendment to the Water Quality Control Plan for the San Diego Basin (9) to Incorporate Total Maximum Daily Loads for Dissolved Copper, Lead, and Zinc in Chollas Creek, Tributary to San Diego Bay, and to Revise the Toxic Pollutants Section of Chapter 3 to Reference the California Toxics Rule (June 2007) <https://www.waterboards.ca.gov/sandiego/water_issues/programs/tmdls/docs/chollas creekmetals/update011509/R9-2007-0043_Signed.pdf> [as of May 20, 2021] (Chollas Creek Metals TMDL)
293 Chollas Creek Metals TMDL, p. 3.
294 San Diego Regional Water Quality Control Board, Total Maximum Daily Loads for Dissolved Copper, Lead, and Zinc in Chollas Creek, Tributary to San Diego Bay (May 2007)
<https://www.waterboards.ca.gov/sandiego/water_issues/programs/tmdls/docs/chollas creekmetals/update011509/Technical_Report.pdf> [as of May 20, 2021] (Chollas Creek Metals TMDL Technical Report)
295 Chollas Creek Metals TMDL Technical Report, p. 49-50.

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Table 77 – Chollas Creek Metals Waste Load Allocations
Pollutant 90 Percent of Dissolved Metal Concentration Numeric Targets (ug/L)
Dissolved Copper (0.90) X (0.96) X exp(0.9422 X ln[hardness] – 1.700) X WER Dissolved Lead (0.90) X [1.46203 – 0.145712 X ln(hardness)] X exp(1.273 X ln[hardness] – 1.460) X WER
Dissolved Zinc (0.90) X (0.978) X exp(0.8473 X ln[hardness] + 0.884) X WER The CTR acute criteria for dissolved copper, lead, and zinc are calculated using water effect ratios (WER), which represents the correlation between the concentrations present in the water column and the concentrations that are biologically available and toxic to aquatic life.

The San Diego Regional Water Board adopted Resolution R9-2017- 0015 which established site-specific WERs for dissolved copper (6.998) and zinc (1.711) in Chollas Creek. In the absence of a site-specific WER, such as for lead, a default value of 1.0 is used.

The CTR acute criteria calculation also requires receiving water body hardness, which results in a floating target that would differ at each sample because the receiving water body hardness is dependent on receiving water body flow. Hardness is defined as the concentration of calcium carbonate (CaCO3) in the water column and has the units of milligram per liter (mg/L). Freshwater aquatic life criteria for certain metals are expressed as a function of hardness because hardness and/or water quality characteristics that are usually correlated with hardness can reduce or increase the toxicities of some metals.

Known site-specific hardness data is used to calculate the waste load allocation instead of requiring Responsible Dischargers to calculate their metal limit by sampling the receiving water body hardness in concurrence with taking a discharge sample. This is consistent with the approach taken in many hardness dependent TMDLs of assigning a hardness value based on existing data. Hardness data for Chollas Creek was obtained by Regional Board TMDL staff from California Integrated Water Quality System (CIWQS). Data analysis was conducted on hardness results from wet-weather sampling events from the Chollas Creek TMDL watershed with sample dates ranging from 1994 to 2017.

All results obtained were marked as part of the Chollas Creek TMDL project, however not all stations had specific location information.

Statistics run on the data set produced a hardness geometric mean of

94.07 mg/L. Table 78 below shows how the CTR equation was used to calculate the acute concentration criteria at a hardness of 94.07 mg/L.

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Table 78 – Chollas Creek Dissolved Metals Waste Load Allocation Translation Pollutant CTR equation
Total Criteria
(ug/L) using
hardness of

94.07 mg/L
90 Percent of
Total Criteria
as the Waste
Load
Allocation
(ug/L)
Translated
Numeric
Effluent
Limitations
(mg/L)*
Copper 6.998 X (exp(0.9422 X
ln[hardness] - 1.7)) 92.4823777 83.23413993 0.083
Lead 1 X (exp(1.273 X
ln[hardness] - 1.460)) 75.5324136 67.97917227 0.068
Zinc 1.711 X (exp(0.8473 X
ln[hardness] + 0.884)) 194.6576544 175.181889 0.175
*Values are rounded to reflect the significant figures of each respective pollutant A geometric mean hardness of Chollas Creek was selected to calculate the criteria for translating each pollutant into a numeric effluent limitation in the Chollas Creek Metals TMDL because it is not feasible or practical to require Responsible Dischargers to collect the ambient hardness of the receiving water body in concurrence with each monitoring sample.

Therefore, Responsible Dischargers are assigned numeric effluent limitations for dissolved copper, lead, and zinc for discharges to Chollas Creek to be met at the construction site’s discharge location(s). · Compliance Actions and Schedule
Responsible Dischargers shall comply with the requirements of this General Permit. Responsible Dischargers that discharge into Chollas Creek and that identify on-site sources of copper, lead, and zinc through the required pollutant source assessment, shall compare all non-visible sampling and analytical results to the applicable numeric effluent limitations for the identified metals.

If an exceedance or failure of a BMP is observed, the Responsible Discharger shall evaluate the BMPs being used and identify and implement a strategy in the site’s SWPPP to prevent potential exceedances of the numeric effluent limitations in the future.

Responsible Dischargers that perform the required pollutant source assessment and implement BMPs specific to preventing or controlling stormwater exposure to the metals’ sources are expected to meet the numeric effluent limitations.

The Chollas Creek Metals TMDL’s final compliance deadline is October 22, 2028. As an interim target, Responsible Dischargers shall apply the translated numeric effluent limitation values as numeric action levels up until the compliance date of October 22, 2028. Future reissuances of this General Permit may incorporate additional or revised compliance ORDER WQ 2022-0057-DWQ
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requirements or interim targets to progress towards the required final compliance when a numeric effluent limitation applies.

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ATTACHMENT A A-1

ATTACHMENT A

ACRONYMS AND TERMS

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCIATED

WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)
Acronym or
Term
Definition
ASBS Areas of Special Biological Significance
ASTM American Society of Testing and Materials; Standard Test Method for Particle-Size Analysis of Soils
ATS Active Treatment System
BAT Best Available Technology Economically Achievable
BCT Best Conventional Pollutant Control Technology
BMP Best Management Practice
BOD Biochemical Oxygen Demand
CBPELSG California Board of Professional Engineers, Land Surveyors and Geologists
CCR California Code of Regulations
CEQA California Environmental Quality Act
CFR Code of Federal Regulations
CGP NPDES General Permit for Stormwater Discharges Associated with Construction and Land Disturbance Activities
CIWQS California Integrated Water Quality System
COI Change of Information
CPESC Certified Professional in Erosion and Sediment Control CPSWQ Certified Professional in Storm Water Quality
CSMP Construction Site Monitoring Program
CTR California Toxics Rule
CWA Clean Water Act
CWC California Water Code
DAR Duly Authorized Representative
DDD Dichlorodiphenyldichloroethane
DDE Dichlorodiphenyldichloroethylene
DDT Dichlorodiphenyltrichloroethane
DWQ Division of Water Quality
ELAP Environmental Laboratory Accreditation Program
ELG Effluent Limitation Guidelines
JTU Jackson Turbidity Units
LID Low Impact Development
LOEC Lowest Observed Effect Concentration
LRP Legally Responsible Person
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LUP Linear Underground and Overhead Projects
MATC Maximum Allowable Threshold Concentration
MDL Method Detection Limit
MRP Monitoring and Reporting Program
MS4 Municipal Separate Storm Sewer System
NAL Numeric Action Level
NEL Numeric Effluent Limitation
NEPA National Environmental Policy Act
NOAA National Oceanic and Atmospheric Administration
NOEC No Observed Effect Concentration
NOI Notice of Intent
NONA Notice of Non-Applicability
NOT Notice of Termination
NPDES National Pollutant Discharge Elimination System
NRCS Natural Resources Conservation Service
NTR National Toxics Rule
NTU Nephelometric Turbidity Units
O&M Operation and Maintenance
OC Organochlorine
PAH Polycyclic Aromatic Hydrocarbon
PCB Polychlorinated Biphenyl
POTW Publicly Owned Treatment Works
PRD Permit Registration Document
Previous Permit State Water Board Order 2009-009-DWQ, as amended by Orders 2010-0014-DWQ and 2012-0006-DWQ
QA/QC Quality Assurance and Quality Control
QAPrP Quality Assurance Program Plan
QSD Qualified SWPPP Developer
QSP Qualified SWPPP Practitioner
Regional Water
Board
Regional Water Quality Control Board
RUSLE Revised Universal Soil Loss Equation
RUSLE2 Revised Universal Soil Loss Equation 2
SMARTS Stormwater Multiple Application and Report Tracking System State Water
Board
State Water Resources Control Board
SWAMP Surface Water Ambient Monitoring Program
SWMM Storm Water Management Model
SWPPP Storm Water Pollution Prevention Plan
TDS Total Dissolved Solids
TMDL Total Maximum Daily Load
TSS Total Suspended Solids
USC United States Code
U.S. EPA United States Environmental Protection Agency
USGS United States Geological Survey
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Water Boards Collectively, the State Water Resources Control Board and the Regional Water Quality Control Boards
WDID Waste Discharge Identification Number
WLA Waste Load Allocation
WER Water Effect Ratio
WET Whole Effluent Toxicity
WQO Water Quality Objective
WQS Water Quality Standard
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ATTACHMENT B B-1

ATTACHMENT B

GLOSSARY

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCIATED

WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)
70 Percent Final Cover
For final construction site stabilization, 70 percent final cover is the permanent vegetative cover that is evenly established over 70 percent of all disturbed and exposed areas of soil (non-paved or non-built). In areas that naturally have low vegetative coverage (e.g., deserts), 70 percent of natural conditions is acceptable.

Active Areas of Construction
Active areas of construction are all areas subject to land surface disturbance activities related to the project including, but not limited to, project staging areas, immediate access areas and storage areas. All previously active areas of construction are considered active areas (unless temporarily defined as inactive areas) until final stabilization is complete.

Active Treatment System
An active treatment system is a treatment technology that employs chemical coagulation, chemical flocculation, or electrocoagulation to reduce turbidity caused by fine suspended sediment, and/or to control pH levels. An active treatment system relies on enclosed computerized systems with pumps, filters, and real-time controls.

Acute Toxicity
Acute toxicity in water is caused by chemical stimuli that rapidly induce a negative effect on aquatic life; in aquatic toxicity tests, acute toxicity is demonstrated by an effect observed within 96 hours or less.

Aerial Deposition
Aerial deposition is the deposition of airborne particulates from construction activities or nearby activities that settle onto surfaces. Such particulates can include, but are not limited to, metals, nutrients, organics, sediment, and trash.

Ancillary Facility
An ancillary facility is a support area required for construction activities of the linear underground and overhead project permitted area. The ancillary facility may be located adjacent to or within the linear underground and overhead project alignment (i.e., transmission/distribution right-of-way) or may be regionally located away from the linear underground and overhead project alignment. Ancillary areas include, but are not limited to, new access roads, helicopter landing zones, laydown yards, staging areas, substations, valve stations, etc.

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ATTACHMENT B B-2
Best Available Technology Economically Achievable (BAT) As defined by U.S. EPA, BAT is a technology-based standard established by the Clean Water Act (CWA) § 304(b)(2) as the most appropriate means available on a national basis for controlling the direct discharge of toxic and nonconventional pollutants to navigable waters. The BAT effluent limitations guidelines, in general, represent the best existing performance of treatment technologies that are economically achievable within an industrial point source category or subcategory.

Best Conventional Pollutant Control Technology (BCT)
As defined by U.S. EPA, BCT is a technology-based standard established by the Clean Water Act (CWA) § 304(b)(4) for the discharge from existing industrial point sources of conventional pollutants including biochemical oxygen demand (BOD), total suspended sediment (TSS), fecal coliform, pH, and oil and grease.1 Best Management Practices (BMPs)
BMPs are management practices and structural controls used to prevent or reduce the discharge of pollutants from runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage to waters of the United States. BMPs include scheduling of activities, prohibitions of practices, operation and maintenance procedures, treatment, and vegetated infiltration basins amongst other practices.

Best Professional Judgment
Best professional judgement is a method used by permit writers to develop technology- based NPDES permit conditions on a case-by-case basis using all reasonably available and relevant data to establish technology-based limits or to determine other appropriate means to control its discharge (U.S. EPA NPDES Permit Writer’s Manual 2010).

Chain of Custody Form
The Chain of Custody form is used to track sample handling as samples progress from sample collection to the analytical laboratory. The Chain of Custody form is then used to track the resulting analytical data from the laboratory to the client. Chain of Custody forms can be obtained from an analytical laboratory upon request.

Coagulation
Coagulation is the clumping of particles in a discharge to settle out impurities, often induced by chemicals such as lime, alum, and iron salts.

Common Plan of Development or Sale
A common plan of development or sale is a contiguous area where multiple separate and distinct construction activities may be taking place at different times on different schedules under one common plan. The "common plan" of development or sale is broadly defined as any announcement or piece of documentation (including a sign, public notice or hearing, sales pitch, advertisement, drawing, permit application, zoning request, computer design, etc.) or physical demarcation (including boundary signs, lot 1 U.S. EPA. Learn about Effluent Guidelines. Web. <https://www.epa.gov/eg/learn- about-effluent-guidelines#BCT> [as of October 19, 2020] ORDER WQ 2022-0057-DWQ
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stakes, surveyor markings, etc.) indicating construction activities may occur on a specific plot. However, broad planning documents, such as land use master plans, conceptual master plans, or broad-based California Environmental Quality Act (CEQA) or National Environmental Policy Act (NEPA) documents that identify potential projects for an agency or facility are not considered common plans of development. For construction projects within a larger common plan of development or sale located at least one-quarter mile apart and the area between the projects is not being disturbed, each individual project may be regulated as a separate construction project if land for interconnecting road, pipeline, or utilities that is part of the same common plan is not concurrently being disturbed.

Construction Site Monitoring Program
Construction site monitoring program is a description of methods and procedures for monitoring discharges at a construction site.

Conveyance System
Conveyance system is a sewer, ditch, pipe, hose, swale, or any engineered feature that is designed to convey water or any combination of such components.

Debris
Debris is litter, rubble, discarded refuse, or remains of destroyed inorganic anthropogenic waste.

Demolition and Pre-Development Site Preparation
Demolition and pre-development site preparation is a construction stage including demolition of existing structures that expose soil, rough grading and/or disking, clearing and grubbing operations, or any soil disturbance prior to mass grading.

Detected Not Quantifiable
Detected not quantifiable is a sample result that is between the method detection limit and the minimum level or reporting limit.

Detention
Detention is the temporary storage of stormwater to improve quality or reduce the volumetric flow rate of discharge or both.

Dewatering
Dewatering is the process of removing excess water in an excavation or impoundment by pumping or other mechanical means.

Discharge Location
Discharge location is a common outlet from a construction site drainage area where stormwater, authorized non-stormwater, or dewatering discharge leaves the site or project boundary, or enters any on-site waters of the United States (e.g., a creek running through a site).

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Discharger
The discharger is a person as defined in Water Code, § 13050(c), which includes companies and governmental bodies, subject to this General Permit. The discharger is responsible for compliance with this Permit, including work done by QSDs, QSPs, and QSP delegates. The following persons may serve as the discharger:

1. A person, company, agency, or other entity that possesses a real property interest (including, but not limited to, fee simple ownership, easement, leasehold, or other rights of way) in the land upon which the construction or land disturbance activities will occur for the regulated site.

2. For linear underground and overhead projects, the utility company, municipality, or other public or private company or agency that owns or operates the linear underground or overhead project.

3. For land controlled by an estate or similar entity, the person who has day-to-day control over the land (including, but not limited to, a bankruptcy trustee, receiver, or conservator).

4. For pollution investigation and remediation projects, any potentially responsible party that has received permission to conduct the project from the holder of a real property interest in the land.

5. For U.S. Army Corps of Engineers projects, the U.S. Army Corps of Engineers may provide written authorization to its bonded contractor to serve as the discharger, provided the U.S. Army Corps of Engineers is also responsible for compliance with the General Permit, as authorized by the Clean Water Act or the Federal Facilities Compliance Act.

6. For projects on public lands, a public agency with a real property interest in the land may provide written authorization via an encroachment permit to another public agency to serve as the discharger, provided that both public agencies remain responsible for compliance with this General Permit.

A contractor is qualified to be a discharger if the contractor satisfies one of the requirements above.

Dose Rate
In applied chemistry, dose rate is dose of a chemical per time unit (e.g., mg/day), sometimes also called dosage or injection rate.

Drainage Area
Drainage area is the area of land that drains water, sediment, pollutants, and dissolved materials to a common outlet or discharge location.

Duly Authorized Representative (DAR)
A Duly Authorized Representative is a named individual or position that has responsibility for the overall operation of the regulated construction project or activities ORDER WQ 2022-0057-DWQ
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including, but not limited to, a superintendent, project manager, or other positions of equivalent or higher responsibility. Additionally, an individual or position that has overall responsibility for environmental matters for the owner or company may be designated as a Duly Authorized Representative. The Legally Responsible Person designates the Duly Authorized Representative through SMARTS, authorizing the Duly Authorized Representative to sign, certify, and electronically submit Permit Registration Documents, Notices of Termination, and any other supporting documents, reports, or information required by this General Permit, the State or Regional Water Boards, or U.S. EPA. A Duly Authorized Representative cannot be a contractor, consultant, or other third party.

Effective Date
An effective date is a date set by the State Water Resources Control Board (State Water Board) during the adoption of an Order, for the date that at least one or more of the Order provisions take effect and the previous Order is rescinded.

Effluent
Effluent is any discharge either to the receiving water or beyond the property boundary controlled by the discharger.

Effluent Limitation
An effluent limitation is any numeric or narrative restriction imposed on quantities, discharge rates, and concentrations of pollutants which are discharged from point sources into waters of the United States, the waters of the contiguous zone, or the ocean.

Erosion
Erosion is the process, by which soil particles are detached and transported by the actions of wind, water, or gravity.

Erosion Control BMPs
Erosion control BMPs is vegetation, such as grasses and wildflowers, and other materials, such as straw, fiber, stabilizing emulsion, protective blankets, rolled erosion control product, etc., placed to stabilize areas of disturbed soils, reduce loss of soil due to the action of water or wind, and prevent water pollution.

Field Measurements
Field measurements are results of testing procedures performed in the field with portable field-testing kits or meters.

Final Stabilization
Final stabilization is established when all soil disturbing activities at each individual parcel within the construction site have been completed, and the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (such as riprap, gabions, or geotextiles) to prevent erosion in a manner consistent with the requirements in this General Permit.

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First Order Stream
A first order stream is a stream with no tributaries.

Flocculants
Flocculants are substances which promote the clumping of particles.

Forecasted Precipitation Event
Forecasted precipitation event is any weather pattern that is forecasted to have a 50 percent or greater chance of producing 0.5 inches of precipitation in a 24-hour period in the project area. The discharger shall obtain precipitation forecast information from the National Weather Service Forecast Office (e.g., by entering the zip code of the project’s location at https://forecast.weather.gov). Precipitation events end when there are two sequential 24-hour periods with less than 0.25 inches of precipitation forecast for each period.

Full Capture System
A full capture system is a treatment control, or series of treatment controls, including but not limited to, a multi-benefit project or a low impact development control that traps all particles that are 5mm or greater, and has a design treatment capacity that is either:

1. Of not less than the peak flow rate, Q, resulting from a one-year, one-hour, storm in the subdrainage area; or

2. Appropriately sized to, and designed to, carry at least the same flows as the corresponding storm drain.

Full Capture System Equivalency
Full capture system equivalency is the trash load that would be reduced if full capture systems were installed, operated, and maintained for all storm drains that capture runoff from the relevant areas of land (e.g., facilities or sites regulated by NPDES permits for discharges of stormwater associated with industrial activity, including construction activity). The full capture system equivalency is a trash load reduction target that the permittee quantifies by using an approach, and technically acceptable and defensible assumptions and methods for applying the approach, subject to the approval of the permitting authority.

Good Housekeeping BMPs
Good housekeeping BMPs are designed to reduce or eliminate the addition of pollutants to construction site runoff through analysis of pollutant sources, implementation of proper handling/disposal practices, employee education, and other actions.

Grading and Land Development Phase
Grading and land development phase includes reconfiguring the topography and slope, including: alluvium removals; canyon cleanouts; rock undercuts; keyway excavations; landform grading; and stockpiling of select material for capping operations.

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Groundwater
Groundwater is water that exists underground in saturated zones beneath the land surface.

Hydraulically Downgradient
Hydraulically downgradient is the direction of stream flow towards a lower elevation.

Hydromodification
Hydromodification is the alteration of the hydrologic characteristics of coastal and non- coastal waters, which in turn could cause degradation of water resources.

Hydromodification can cause excessive erosion and/or sedimentation rates, causing excessive turbidity, channel aggradation and/or degradation.

Inactive Project
Inactive project is where all construction activities (including passive treatment technology, active treatment systems, and/or active equipment), are fully stabilized and will be suspended for 30 days or more.

Infeasible
Infeasible means that the discharger has demonstrated that the specific requirement is not technologically possible, or not economically practicable and achievable in light of best industry practices.

K Factor
The K factor is the soil erodibility factor used in the Revised Universal Soil Loss Equation (RUSLE). The K factor represents the combination of detachability of the soil, runoff potential of the soil, and the transportability of the sediment eroded from the soil.

Legally Responsible Person
The Legally Responsible Person is a representative of a permittee and signatory that is legally designated to sign, certify, and electronically submit any documents required by the General Permit, the State or Regional Water Board, or U.S. EPA. An LRP must be one of the following:

1. For a corporation or limited liability company: a responsible corporate officer. For the purpose of this section, a responsible corporate officer means: (a) a president, secretary, treasurer, or vice-president of the corporation in charge of a principal business function, or any other person who performs similar policy or decision- making functions for the corporation or limited liability company; or (b) the manager of the facility if authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures;

2. For a partnership or sole proprietorship: a general partner or the proprietor, respectively;

3. For a municipality, state, federal, or other public agency: a principal executive officer, ranking elected official, city manager, council president, or any other authorized ORDER WQ 2022-0057-DWQ
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public employee with managerial responsibility over the construction or land disturbance project (including, but not limited to, project manager, project superintendent, or resident engineer);

4. For an individual: the individual; or

5. For any type of entity not listed above (e.g., trusts, estates, receivers): an authorized person with managerial authority over the construction or land disturbance project.

Maximum Allowable Threshold Concentration
Maximum allowable threshold concentration is the allowable concentration of residual, or dissolved, coagulant/flocculant in effluent. The MATC shall be coagulant/flocculant- specific, and based on toxicity testing conducted by an independent, third-party laboratory. Typically, the MATC is equal to the geometric mean of the NOEC (No Observed Effect Concentration) and LOEC (Lowest Observed Effect Concentration) Acute and Chronic toxicity results for most sensitive species determined for the specific coagulant. The most sensitive species test shall be used to determine the MATC.

Method Detection Limit
Method detection limit is the minimum concentration of a substance that can be measured and reported with 99 percent confidence that the analyte concentration is greater than zero.

Minimum Level or Reporting Limit
Minimum level or reporting limit is the lowest level at which the entire analytical system must give a recognizable signal and acceptable calibration point for the analyte. It is equivalent to the concentration of the lowest calibration standard in a method, assuming that all method-specified sample weights, volumes, and cleanup procedures have been employed.

Multi-Benefit Project
Multi-benefit project is a treatment control project designed to achieve the benefits set forth in California Water Code § 10562, subdivision (d). Examples include projects designed to: infiltrate, recharge, or store stormwater for beneficial reuse; develop or enhance habitat and open space through stormwater and non-stormwater management; and/or reduce stormwater and non-stormwater runoff volume.

Natural Channel Evolution
Natural channel evolution is the physical trend in channel adjustments following a disturbance that causes the river to have more energy and degrade or aggrade more sediment. Channels have been observed to pass through 5 to 9 evolution types. Once a channel passes though the suite of evolution stages, the channel will rest in a new state of equilibrium.

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Non-Detect
Non-detect is a sample result represented by “ND” in which the concentration of the subject pollutant analyte is less than the method detection limit, and therefore not detectable by the laboratory method and/or equipment used.

Non-Stormwater Discharges
Non-stormwater discharges are discharges that do not originate from precipitation events. They can include, but are not limited to, discharges of process water, air conditioner condensate, non-contact cooling water, vehicle wash water, sanitary wastes, concrete washout water, paint wash water, irrigation water, dust control over- wetting, or pipe testing water.

Non-Stormwater Pollution Controls
Non-stormwater pollution controls are the general site and materials management measures that directly or indirectly aid in minimizing the non-stormwater originated discharge of sediment and other construction related pollutants from the construction site.

Non-Structural Controls
Non-structural controls are best management practices that do not involve a structured or engineered solution. Non-structural controls include measures including education, site planning, and stormwater management regulations.

Non-Visible Pollutants
Non-visible pollutants associated with a specific site or activity that can have a negative impact on water quality but cannot be seen though observation (e.g., chlorine).

Numeric Action Level
A numeric action level (e.g., a pH range, turbidity value, or concentration) is a level that triggers a required evaluation of the effectiveness of best management practices implemented on the subject construction site, and the required implementation of additional corrective actions necessary to reduce the subject pollutant below the numeric action level. The numeric action level compliance location applies to each sample location and/or corresponding discharge location.

Numeric Action Level Exceedance
Non-TMDL numeric action level exceedance: A numeric action level exceedance occurs when the field reading for the one sample taken during each day of a qualifying precipitation event at each sample and/or discharge location, exceeds an applicable numeric action level. A numeric action level exceedance is not a violation of this General Permit. A discharger failing to report and failing to modify implementation of its best management practices to prevent further numeric action level exceedance(s), is a violation of this General Permit.

TMDL-related numeric action level exceedance: A TMDL-related numeric action level exceedance occurs on the second, and each subsequent, analytical result for samples taken from any and all discharge location(s) within the same drainage area, during the ORDER WQ 2022-0057-DWQ
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same reporting year and taken in accordance with Attachment D or E Section III.D.3, that is above the concentration set forth in an applicable numeric action level. A numeric action level exceedance is not a violation of this General Permit; however, it is a violation when the discharger fails to report and respond to the numeric action level exceedance(s).

Numeric Effluent Limitation
Numeric effluent limitation is a technology-based or water quality-based limit (e.g., pH range, turbidity value, or concentration) established for discharges covered under this General Permit. The numeric effluent limitation compliance location(s) applies to each sample and/or discharge location at the point of discharge from an active treatment system if applicable.

Numeric Effluent Limitation Exceedance
Active treatment system numeric effluent limitation exceedance: An active treatment system numeric effluent limitation exceedance occurs when the analytical result for the samples taken during operation of an active treatment system exceeds an applicable numeric effluent limitation. A numeric effluent limitation exceedance is a violation of this General Permit and subject to mandatory minimum penalties.

TMDL-related numeric effluent limitation exceedance: A TMDL-related numeric effluent limitation exceedance occurs on the second, and each subsequent, analytical result for samples taken from any and all discharge location(s) within the same drainage area, during the same reporting year and taken in accordance with Attachment D or E Section III.D.3, that is above the concentration set forth in an applicable numeric effluent limitation. Each numeric effluent limitation exceedance after the first instance is a violation of this General Permit and subject to mandatory minimum penalties.

Passive Treatment
Passive treatment is the application of natural or synthetic chemicals and products to reduce turbidity in discharges through coagulation and flocculation. Passive treatment does not rely on computerized, enclosed systems with pumps, filters, and real-time controls. Passive treatment may include pumps where they are necessary to move water around the construction site.2 Passive treatment products are available in a variety of forms and may be land-applied for soil stabilization (e.g., bonded fiber matrixes, hydromulches) or water-applied for sediment removal (e.g., liquid treatment chemicals, powders, slow-releasing solid blocks/socks).

Permanent Control Measures
Permanent control measures are the erosion prevention materials designed to provide long-term protection to underlying soils. This may include, but is not limited to buildings, paving a uniform (evenly distributed, without large bare areas) perennial vegetative cover, riprap, gabions, or biodegradable rolled erosion control products (RECP). 2 U.S. EPA. 2017 Construction General Permit. Web. January 11, 2017. <https://www.epa.gov/npdes/epas-2017-construction-general-permit-cgp-and-related- documents> [as of October 19, 2020]
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pH
pH is the unit universally used to express the intensity of the acid or alkaline condition of a water sample. The pH of natural waters tends to range between 6 and 9, with neutral being 7. Extremes of pH can have deleterious effects on aquatic systems.

Post-Construction BMPs
Post-construction BMPs are structural and non-structural controls which detain, retain, infiltrate, and/or filter out pollutants discharged to receiving waters after a construction project is completed. Low impact development features are considered a type of post- construction BMP.

Precipitation Event
Precipitation event is any weather pattern that results in precipitation (rain, snow, sleet, or hail).

Programmatic Permitting
Programmatic permitting is an approach for linear underground and overhead project dischargers to obtain General Permit coverage for multiple non-contiguous sites with similar scope and construction activities, that are located within one Regional Water Board boundary and have the same Legally Responsible Person.

Project
Project is the area that includes sites where land is disturbed and also includes the areas of activities that do not disturb land.

Property Boundary
Property boundary or the area enclosed by the property lines. Property boundary includes project area and sites.

Qualified SWPPP Developer (QSD)
Qualified SWPPP developer is a qualified stormwater professional authorized by the discharger to develop and revise SWPPPs.

Qualified SWPPP Practitioner (QSP)
Qualified SWPPP practitioner is a qualified stormwater professional authorized by the discharger to conduct non-stormwater and stormwater visual observations, sampling, and implementation of all elements of the SWPPP.

Qualifying Precipitation Event
Qualifying precipitation event is any weather pattern that is forecast to have a 50 percent or greater Probability of Precipitation (PoP) and a Quantitative Precipitation Forecast (QPF) of 0.5 inches or more within a 24-hour period. The event begins with the 24-hour period when 0.5 inches has been forecast and continues on subsequent 24- hour periods when 0.25 inches of precipitation or more is forecast.

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R Factor
R factor is the erosivity factor used in the Revised Universal Soil Loss Equation (RUSLE). The R factor represents the erosivity of the climate at a particular location. An average annual value of R is determined from historical weather records using erosivity values determined for individual storms. The erosivity of an individual storm is computed as the product of the storm's total energy, which is closely related to storm amount, and the storm's maximum 30-minute intensity.

Regional Water Quality Control Board (Regional Water Board) A Regional Water Board is a semi-autonomous board comprised of board members appointed by the Governor and confirmed by the state Senate. California has nine Regional Water Boards with jurisdictions based on watersheds. A Regional Water Board may delegate its authority to the executive officer to the board, or other designated staff.

Remaining Sub-Sampled Material
Remaining sub-sampled material is the material (for example: organic material, gravel, etc.) that remains after the organisms to be identified have been removed from the subsample for identification. (Generally, no macroinvertebrates are present in the remaining subsampled material, but the sample needs to be checked and verified using a complete Quality Assurance (QA) plan).

Reporting Period
A reporting period is a specified period of time in which pertinent report information is applicable. For example, a standard reporting period in this Order is July 1 through June 30 of each year.

Responsible Discharger
Responsible dischargers are dischargers who:

1. Discharge stormwater and authorized non-stormwater directly, or through a municipal separate sewer system (MS4) or other conveyance, to impaired water bodies or watersheds identified in a U.S. EPA-approved TMDL with a waste load allocation assigned to construction stormwater sources; and

2. Have identified, through the site-specific pollutant source assessment, that one or more pollutants specific to the TMDL are present on-site with the potential to enter construction stormwater discharges.

Revised Universal Soil Loss Equation (RUSLE)
Revised universal soil loss equation is the empirical model that calculates average annual soil loss as a function of rainfall and runoff erosivity, soil erodibility, topography, erosion controls, and sediment controls.

Revised Universal Soil Loss Equation 2 (RUSLE2)
Revised universal soil loss equation 2 is the updated Windows®-based empirical model that calculates average annual soil loss as a function of rainfall and runoff erosivity, soil ORDER WQ 2022-0057-DWQ
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erodibility, topography, erosion controls, and sediment controls. This includes subsequent equivalent versions of this model.

Routine Maintenance
Routine maintenance are activities intended to maintain the original line and grade, hydraulic capacity, and/or original purpose of a facility. The Order further defines routine maintenance (Section II.B.1) for road and highway projects as the replacement of the structural section, but not when the activity exposes the underlying soil or erodible subgrade. The road surface and base are not part of the subgrade. As such, those portions of a project that remove the paved road surface and base down to the erodible subgrade and/or underlying soil would not be considered routine maintenance.

Runoff Control BMPs
Runoff control BMPs are designed to control the peak volume and flow rate, or prevent scour due to concentrated flows.

Run-on
Run-on are discharges that originate offsite and flow onto the property of a separate project site.

Sampling Location
Sampling location for traditional construction projects: An identified discharge location where samples of stormwater, non-stormwater, or dewatering discharges are obtained to determine compliance with requirements in this General Permit.

Sampling location for linear underground and overhead projects: An identified discharge location, representative of the project’s construction activities, where samples of stormwater, non-stormwater, or dewatering discharges are obtained to determine compliance with requirements in this General Permit.

Secondary Containment
Secondary containment is a device or control measure in addition to the primary containment that is used to stop a discharge of pollutants or hazardous material from leaving a specified area.

Sediment
Sediment is solid particulate matter, both mineral and organic, that is in suspension, is being transported, or has been moved from its site of origin by air, water, gravity, or ice and has come to rest on the earth's surface either above or below sea level.

Sediment Control BMPs
Sediment control BMPs are practices and controls that trap soil particles after erosion by rain, flowing water, or wind. They include those practices that intercept and slow or detain the flow of stormwater to allow sediment to settle and be trapped (e.g., silt fence, sediment basin, fiber rolls, etc.).

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Sedimentation
Sedimentation is the process of deposition of suspended matter carried by water, wastewater, or other liquids, by gravity. It is usually accomplished by reducing the velocity of the liquid below the point at which it can transport the suspended material.

Sensitive Watershed
Sensitive watershed is a watershed draining into a receiving water body listed on the State Water Board’s approved CWA 303(d) list for sedimentation/siltation, turbidity, or a water body designated with beneficial uses of cold, spawn, and migratory.

Settleable Solids
Settleable solids is a solid material that can be settled within a water column during a specified time frame. It is typically tested by placing a water sample into an Imhoff settling cone and then allowing the solids to settle by gravity for a given length of time.

Results are reported either as a volume of milliliter per liter (mL/L) or as a concentration (milligrams per liter (mg/L)).

Sheet Flow
Sheet flow is overland flow of water that occurs in areas where there are no defined channels where the water spreads out over a large area at a uniform depth.

Site
A site is the area disturbed where the construction activity is physically located or conducted, including staging, storage, and access areas.

Site Operating Hours
Site operating hours are the time periods when the site is staffed to conduct any function related to the construction activity.

Soil Amendment
A soil amendment is any material that is added to the soil to change its chemical properties, engineering properties, or erosion resistance that could become mobilized by stormwater.

Source
Source is any construction activity, material, or area that causes or contributes to pollutants in stormwater.

Stormwater
Stormwater is rain, snowmelt, or any other liquid or solid precipitation that may result in runoff, and drainage from a site.

Streets and Utilities Phase
Streets and utilities phase is the construction stage including excavation and street paving, lot grading, curbs, gutters and sidewalks, public utilities, public water facilities including fire hydrants, public sanitary sewer systems, storm sewer system, and/or other drainage improvements.

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Structural Controls
Structural controls are any structural facility or fabrication designed and constructed to mitigate the adverse impacts of stormwater and urban runoff pollution.

Surface Runoff
Surface runoff is the portion of stormwater that does not infiltrate into the ground or evaporate, but instead flows overland onto adjacent land or watercourses or is routed to stormwater conveyance systems.

Topsoil
Topsoil is the uppermost part of the soil profile, which is the most favorable material for plant growth. It is typically rich in organic matter.

Total Maximum Daily Load (TMDL)
A TMDL is the sum of the maximum amount of a pollutant that a waterbody can receive per day and still meet state water quality standards. It is the sum of the individual Waste Load Allocations (WLAs) for point sources, the load allocations for nonpoint and natural background sources, and the margin of safety.

Total Suspended Solids (TSS)
The measure of total suspended solids is the measure of the suspended solids in a water sample which includes inorganic substances, such as soil particles and organic substances, such as algae, aquatic plant/animal waste, particles related to industrial/sewage waste, etc. The TSS test measures the concentration of suspended solids in water by measuring the dry weight of a solid material contained in a known volume of a sub-sample of a collected water sample. Results are reported in mg/L.

Toxicity
Toxicity is the adverse response(s) of organisms to chemicals or physical agents ranging from mortality to physiological responses such as impaired reproduction or growth anomalies.

Trash
Trash is all improperly discarded solid material from any production, manufacturing, or processing operation including, but not limited to, products, product packaging, or containers constructed of plastic, steel, aluminum, glass, paper, or other synthetic or natural materials.

Tributary
Tributary is a smaller river or stream that flows into a larger river or stream.

Turbidity
Turbidity is the optical condition and cloudiness of water caused by suspended or dissolved particles or colloids. Turbidity is quantified by the degree to which light traveling through a water column is scattered by the suspended organic and inorganic particles it contains. The turbidity test is reported in Nephelometric Turbidity Units (NTU) or Jackson Turbidity Units (JTU) with a calibrated turbidity meter.

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Vertical Construction Phase
Vertical construction phase is the build out of structures from foundations to roofing, including rough landscaping.

Waste Load Allocation (WLA)
Waste load allocation is the portion of a receiving water’s loading capacity that is allocated to one of its existing or future point sources of pollution.

Water Effect Ratio (WER)
Water effect ratio is a factor that can be used per U.S. EPA water quality criteria (WQC) regulations, to customize national aquatic life criteria to reflect site-specific water column conditions. The WER is used to derive site-specific criteria that maintain the level of protection of aquatic life intended by the “Guidelines for deriving numerical national WQC” (U.S. EPA 1985).

Waters of the United States
Waters of the United States is defined by the federal Environmental Protection Agency in 40 Code of Federal Regulations § 122.2.

Water Quality Objectives (WQO)
Water quality objectives are defined in the California Water Code as limits or levels of water quality constituents or characteristics, which are established for the reasonable protection of beneficial uses of water or the prevention of nuisance within a specific area.

Water Quality Standards
Water quality standards consists of beneficial uses, water quality objectives to protect those uses, an antidegradation policy, and policies for implementation. Water quality standards are established in Regional Water Quality Control Plans (Basin Plans) and statewide Water Quality Control Plans. U.S. EPA has also adopted water quality criteria (the same as objectives) for California in the National Toxics Rule and California Toxics Rule.

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ATTACHMENT C

CONTACTS

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCAITED

WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)
State Water Resources Control Board
www.waterboards.ca.gov
P.O. Box 1977
Sacramento, CA 95812-1977
[email protected]
Division of Financial Assistance: (916) 341-5700
Division of Water Quality: (916) 341-5455
Office of Enforcement: (916) 341-5272
Office of Public Affairs: (916) 341-5254
Office of Legislative Affairs: (916) 341-5251
Office of the Ombudsman: (916) 341-5254

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ATTACHMENT C
Regional Water Quality Control Board Stormwater Program Contacts NORTH COAST REGION (1)
[email protected]
5550 Skylane Boulevard, Suite A
Santa Rosa, CA 95403
(707) 576-2220
CENTRAL COAST REGION (3)
[email protected]
895 Aerovista Place, Suite 101
San Luis Obispo, CA 93401
(805) 549-3147
CENTRAL VALLEY REGION (5S)
[email protected]
11020 Sun Center Drive, Suite 200
Rancho Cordova, CA 95670-6114
(916) 464-3291
FRESNO BRANCH OFFICE (5F)
[email protected]
1685 E Street
Fresno, CA 93706
(559) 445-5116
VICTORVILLE BRANCH OFFICE (6V)
[email protected]
15095 Amargosa Road— Bldg 2,
Suite 210
Victorville, CA 92394
(760) 241-6583
SANTA ANA REGION (8)
[email protected]
3737 Main Street, Suite 500
Riverside, CA 92501-3348
(951) 782-4130
SAN FRANCISCO BAY REGION (2)
[email protected]
1515 Clay Street, Suite 1400
Oakland, CA 94612
(510) 622-2402
LOS ANGELES REGION (4)
[email protected]
320 W. 4th Street, Suite 200
Los Angeles, CA 90013
(213) 576-6600
REDDING BRANCH OFFICE (5R)
[email protected]
364 Knollcrest Drive, Suite 205
Redding, CA 96002
(530) 224-4845
LAHONTAN REGION (6SLT)
[email protected]
2501 Lake Tahoe Blvd
South Lake Tahoe, CA 96150
(530) 542-5400
COLORADO RIVER REGION (7)
[email protected]
73-720 Fred Waring Drive, Suite 100
Palm Desert, CA 92260
(760) 346-7491
SAN DIEGO REGION (9)
[email protected]
2375 Northside Drive, Suite 100
San Diego, CA 92108-2700
(619) 516-1990

STORMWATER STAFF DIRECTORY
https://www.waterboards.ca.gov/water_issue
s/programs/stormwater/contact.html
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D 1

ATTACHMENT D

TRADITIONAL CONSTRUCTION RISK LEVEL REQUIREMENTS

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES

ASSOCIATED WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES (GENERAL PERMIT)
I. GENERAL REQUIREMENTS
Risk Level 1, 2, and 3 dischargers shall implement the following minimum best management practices (BMPs) to reduce or prevent pollutants in construction stormwater discharges, monitoring requirements, and reporting requirements. If a requirement in this attachment does not specify a specific Risk Level, then the requirement applies to Risk Level 1, 2, and 3 dischargers.

II. MINIMUM BEST MANAGEMENT PRACTICES
II.A. Good Site Management "Housekeeping"
II.A.1. Dischargers shall implement good site management (i.e., "housekeeping") measures for construction materials that could potentially be a threat to water quality if discharged or exposed to stormwater. At a minimum, dischargers shall implement the following good housekeeping measures:
a. Identify and protect the products used and/or expected to be used and the end products that are produced and/or expected to be produced from exposure to stormwater. Products do not include materials and equipment that are designed to be outdoors and exposed to environmental conditions (e.g., poles, equipment pads, cabinets, conductors, insulators, bricks, roofing, and siding);
b. Apply BMPs to erodible stockpiled construction materials (e.g., soil, spoils, fly- ash, stucco, hydrated lime) to prevent erosion and pollutant transport; c. Store chemicals in watertight containers with secondary containment to prevent any spillage or leakage or store in a completely enclosed storage area;
d. Minimize exposure of construction materials to precipitation. Construction materials do not include materials and equipment that are designed to be outdoors and exposed to environmental conditions (e.g., poles, equipment pads, cabinets, conductors, insulators, bricks);
e. Implement BMPs to control the off-site tracking of sediment and loose construction and landscape materials; and
f. Implement BMPs to control the discharge of plastic materials and limit the use of plastic materials when more sustainable, environmentally friendly alternatives exist. Dischargers shall consider the use of plastic materials resistant to solar degradation where plastic materials are deemed necessary.

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ATTACHMENT D D-2
II.A.2. Dischargers shall implement good housekeeping measures for waste management, which, at a minimum, shall consist of the following:
a. Minimize the discharge of pollutants from equipment and vehicle washing, wheel wash water, masonry wash waters, and other wash waters. Wash waters shall be captured and treated prior to discharge, or disposed of at a permitted facility that can accept that waste, to mitigate impacts to water quality;
b. Provide containment (e.g., secondary containment) of sanitation facilities (e.g., portable toilets) to prevent discharges of pollutants to the stormwater drainage system or receiving water;
c. Clean or replace sanitation facilities and inspect them regularly for leaks and spills;
d. Keep debris or trash in waste containers if it is subject to transport from the site by wind or runoff;
e. Cover waste disposal containers at the end of every business day and during a precipitation event;
f. Prevent discharges from waste disposal containers to the stormwater drainage system or receiving water (e.g., containers with solid bottoms and regular maintenance);
g. Contain and securely protect stockpiled waste material from wind and precipitation unless actively being used; and
h. Secure and contain concrete washout areas and other washout areas that may contain additional pollutants to minimize discharge into the underlying soil and onto surrounding areas. Washout areas shall be covered prior to and during a precipitation event.

II.A.3. Dischargers shall implement good housekeeping for vehicle/equipment storage and maintenance, which shall consist of the following:
a. Contain fuel, grease, and oil to prevent them from leaking into ground, storm drains, or surface waters;
b. Place all equipment or vehicles, which are to be fueled, maintained, and/or stored in a designated area with BMPs installed; and
c. Clean leaks immediately and dispose of leaked materials properly in accordance with the law.

II.A.4. Dischargers shall implement good housekeeping for landscape materials, which shall consist of the following:
a. Contain and protect stockpiled materials such as mulches and topsoil, or other erodible landscape materials, from wind and precipitation unless being actively used;
b. Contain packaged landscape materials (e.g., fertilizers) when they are not being actively used;
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ATTACHMENT D D-3
c. Discontinue the application of any erodible landscape material at least 2 days before a forecasted precipitation event as defined in Attachment B or during periods of precipitation; and
d. Apply erodible landscape material at quantities and rates in accordance with manufacturer recommendations or based on written specifications by knowledgeable and experienced field personnel;
II.A.5. Dischargers shall implement good housekeeping measures on the construction site to control the aerial deposition of site materials and from site operations.

Such particulates can include, but are not limited to, metals, nutrients, organics, sediment, other particulates, and trash.

II.A.6. Dischargers shall document all housekeeping BMPs in the SWPPP that correspond to the nature and phase of the construction activities. Construction phases at traditional land development projects include demolition and pre- development site preparation phase, grading and land development phase, streets and utilities phase, vertical construction phase, and final landscaping and site stabilization phase.

II.B. Non-Stormwater Management
II.B.1. Dischargers shall implement the following measures to control all non-stormwater discharges during construction:
a. Wash vehicles in such a manner as to prevent non-stormwater discharges to surface waters or municipal separate sewer system drainage systems; b. Clean streets in such a manner as to prevent unauthorized non-stormwater discharges from reaching surface water or municipal separate sewer system drainage systems; and
c. Eliminate any non-stormwater discharges not authorized in Section IV.A of this General Permit’s Order.

II.C. Preserve Existing Topsoil
II.C.1. Dischargers shall preserve existing topsoil, unless infeasible, through the following practices:
a. Stockpiling existing topsoil, or transferring topsoil to other locations, to deploy and reestablish vegetation prior to termination of coverage; and b. Stabilizing disturbed topsoil during construction.

Preserving existing topsoil is not required where the intended function of a specific area of the site dictates that the topsoil be disturbed or removed.1 1 Examples may include the removal of topsoil containing invasive seedbanks, lack of space to stockpile topsoil, and sites that are designed to be highly impervious after construction with little to no vegetation intended to remain.

ORDER WQ 2022-0057-DWQ
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ATTACHMENT D D-4
II.D. Erosion Control
II.D.1. Dischargers shall implement the following practices to eliminate or minimize site erosion. Erosion control BMPs (except for sprayed products) shall be available on-site or at a nearby location (e.g., common lay-down yard), year-round with trained persons able to deploy the product under the direction of the Qualified SWPPP Practitioner:
a. Implement effective wind erosion control;
b. Preserve existing vegetation;
c. Minimize the amount of soil exposed during construction activity; d. Minimize the disturbance of steep slopes;
e. Schedule earthwork to minimize the amount of disturbed area when feasible; f. Immediately initiate stabilization for disturbed areas whenever earth disturbing activities have permanently ceased on any portion of the site, or temporarily ceased on any portion of the site and will not resume for a period exceeding 14 calendar days;2
g. Minimize soil compaction in areas other than where the intended function of a specific area dictates that it be compacted;
h. Reestablish vegetation or non-vegetative erosion controls as soon as practicable;
i. If feasible, divert up gradient run-on water from contacting areas of exposed soils disturbed by construction activities or convey run-on through the site in a manner that prevents erosion from areas of construction and does not compromise the effectiveness of erosion, sediment, and perimeter controls; j. Run-on water flowing onto a site from off-site areas may be separated from a site’s stormwater discharge to eliminate commingled contribution. Run-on diversion shall occur prior to entering an area affected by construction activity.

Run-on flow diversion shall be conveyed through or around the construction activity in plastic pipe or an engineered conveyance channel in a manner that will not cause erosion due to flow diversion. Run-on combined with a site’s stormwater discharge is considered a stormwater discharge. k. Limit the use of plastic materials when more sustainable, environmentally friendly alternatives exist. Where plastic materials are deemed necessary, the 2 In arid, semiarid, and drought-stricken areas where initiating vegetative stabilization measures immediately is infeasible, alternative stabilization measures shall be employed as specified by the Regional Water Board. Stabilization shall be completed within a period of time determined by the Regional Water Board. In limited circumstances stabilization may not be required if the intended function of a specific area of the site necessitates that it remains disturbed.

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ATTACHMENT D D-5
discharger shall consider the use of plastic materials resistant to solar degradation;
l. Control stormwater and non-stormwater discharges to minimize downstream channel and bank erosion; and
m. Control peak flowrates and total volume of stormwater and authorized non- stormwater discharges to minimize channel and streambank erosion and scour in the immediate vicinity of discharge points.

II.D.2. Dischargers that stabilize soil using bonded-fiber matrices, hydromulches, spray tackifiers, or other land-applied products shall:
a. Apply the product according to the manufacturer’s instructions and guidance; and
b. Apply the product according to the manufacturer’s guidance to allow for ample cure time and to prevent treatment chemicals from being transported by runoff.

II.E. Sediment Controls
II.E.1. Dischargers shall implement the following site sediment controls:
a. Establish and maintain effective perimeter controls; b. Stabilize all construction entrances and exits to sufficiently control erosion and sediment discharges from the site; and
c. Design, install, and maintain effective sediment controls to minimize the discharge of pollutants utilizing site-specific BMPs.

At a minimum, design sediment basins and impoundments according to the method provided in the California Stormwater Quality Association Construction BMP Handbook3 and utilize outlet structures that withdraw water from the surface. Dischargers utilizing sediment basins shall complete installation prior to other land disturbance activities.

II.F. Additional Risk Level 2 and 3 Requirements:

II.F.1. Risk Level 2 and 3 dischargers shall implement the following additional erosion and sediment control BMPs for areas under active4 construction:
3 California Stormwater Quality Association (CASQA), Construction BMP Handbook (January 2015), <https://www.casqa.org/sites/default/files/casqa-handbook- construction/master_hanbook_file_2015_sec.pdf> [as of May 20, 2021] (CASQA Construction BMP Handbook)
4 Active areas of construction are areas undergoing land surface disturbance and associated site areas. This includes construction activity during the preliminary phase, mass grading phase, streets and utilities phase, and the vertical construction phase.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-6
a. Design and construct cut and fill slopes in a manner to ensure slope stability and to minimize erosion including, but not limited to, these practices:
i. Reduce continuous slope length using terracing and diversions; ii. Reduce slope steepness; and
iii. Roughen slope surfaces with large cobble or track walking. b. Install linear sediment controls along the toe of the slope, face of the slope, and at the grade breaks of exposed slopes according to sheet flow lengths as shown in Table 1 until the slope has reached Notice of Termination conditions for erosion protection. When infeasible to comply with Table 1 due to site- specific geology or topography, the QSD shall include in the SWPPP a justification for the use of an alternative method to protect slopes from erosion and sediment loss.

Table 1 - Critical Slope and Sheet Flow Length Combinations for Linear Sediment Reduction Barrier
Slope Ratio
(Vertical to Horizontal) Sheet flow length not to exceed ≤ 1:20 Per QSD’s specification.
> 1:20 to ≤ 1:4 35 feet
> 1:4 to ≤ 1:3 20 feet
> 1:3 to ≤ 1:2 15 feet
> 1:2 10 feet
II.F.2. Limit construction activity traffic to and from the project to entrances and exits that employ effective controls to prevent off-site tracking of sediment.

II.F.3. Maintain and protect all storm drain inlets, perimeter controls, and BMPs at entrances and exits (e.g., tire wash off locations).

II.F.4. Remove any excess sediment or other construction activity-related materials that are deposited on the impervious roads by vacuuming or sweeping prior to any precipitation event.

II.F.5. Implement additional site-specific sediment controls upon written request by the Regional Water Boards when the implementation of the other requirements in this Section are determined to inadequately protect the site’s receiving water(s).

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ATTACHMENT D D-7
II.G. Surface Water Buffer5
II.G.1. Dischargers shall provide and maintain natural buffers and/or equivalent erosion and sediment controls when a water of the U.S. is located within 50 feet of the site’s earth disturbances, unless infeasible.

II.G.2. Dischargers shall comply with one of the following alternatives for any discharges to waters of the U.S. located within 50 feet of a site’s earth disturbances:
a. Provide and maintain a 50-foot undisturbed natural buffer from the edge of the disturbed area to the top of bank;
b. Provide and maintain an undisturbed natural buffer that is less than 50 feet and is supplemented by erosion and sediment controls that achieve, in combination, the sediment load reduction equivalent to a 50-foot undisturbed natural buffer. The equivalent sediment load may be calculated using RUSLE2 or another method approved by the Regional Water Board; or c. Implement erosion and sediment controls to achieve the sediment load reduction equivalent to a 50-foot undisturbed natural buffer when infeasible to provide and maintain an undisturbed natural buffer of any size. The equivalent sediment load may be calculated using RUSLE2 or another method approved by the Regional Water Board.

II.H. Pesticide Application
Dischargers shall only apply pesticides that have been authorized for use through California Department of Pesticide Regulation. The application of pesticides shall follow manufacturer’s guidance.

II.I. Demolition of Existing Structure
Dischargers shall prevent exposing demolition materials to precipitation. Demolition materials should be covered with an impermeable barrier such as, but not limited to, plastic sheeting prior to precipitation to prevent known contaminants from being mobilized. Dischargers unable to cover demolished material that were not previously investigated or found to be absent of applicable pollutants in reportable quantities shall sample for any non-visible pollutants that may be in stormwater 5 The surface water buffer requirements apply to work above the top-of-bank or high- water level of waters of the United States. Work within a channel or streambed (water body-dependent construction), Clean Water Act § 404 projects with a § 401 certification, and projects where no natural surface buffer exists (e.g., concrete channelization) are exempt from the requirements. All types of in-channel work may be regulated under § 401 (Clean Water Act - Regional Boards), § 404 (Clean Water Act - Army Corps of Engineers), or §1602 (California Fish and Game Code).

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-8
discharges such as, but not limited to, asbestos, leaded paint, or Poly Chlorinated Biphenyls (PCBs)6.

II.J. Maintenance and Repair
II.J.1. Dischargers shall begin maintaining, repairing, and/or implementing design changes (reviewing alternatives that have not been used yet) to BMPs within 72 hours of identification of failures or other shortcomings and complete the changes as soon as possible, prior to the next forecasted precipitation event.

II.J.2. Dischargers shall have a Qualified SWPPP Practitioner (QSP) verify all BMP maintenance and repairs were appropriately implemented during the next visual inspection following completion. The QSP may delegate BMP maintenance and repair verification to an appropriately trained delegate.

III. MONITORING REQUIREMENTS
III.A. General Requirements
The monitoring requirements of this Section are issued pursuant to Water Code § 13383 and specifies monitoring requirements for dischargers subject to this Order.

All dischargers shall implement the Construction Site Monitoring Program in compliance with this Section at the time of the commencement of construction activity and shall continue implementation until the project is complete and the project site is stabilized as defined in Section III.H in the Order.

III.B. Monitoring Exceptions
III.B.1. Dischargers shall conduct visual inspections and collect samples to meet the requirements of this Attachment. Dischargers are not required to physically conduct visual inspections or collect samples under the following conditions:
a. During dangerous weather conditions such as electrical storms, flooding, and high winds above 40 miles per hour;
b. Outside of scheduled site operating hours; or
c. When the site is not accessible to personnel.

III.B.2. For inactive projects, dischargers may reduce the visual inspection frequency and suspend sampling per Section III.G of the Order. Dischargers shall provide an explanation with supporting information for all missed visual inspections or sampling required by this Attachment, to be included in the Annual Report. 6 PCBs were used between January 1, 1950 and January 1, 1980 and should be considered to be potentially present in structures built during that timeframe. “Structure”, in this instance, shall have been constructed with floor space (such as a building).

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-9
III.C. Visual Inspection Requirements
III.C.1. Dischargers shall perform visual inspections, based on their Risk Level, in accordance with Table 2 below. The purpose of visual inspections is, to identify and record BMPs that need maintenance to operate effectively, that have failed, or that could fail to operate as intended. Except as specified in Section III.C.3 below, inspectors shall be the Qualified SWPPP Developer, Qualified SWPPP Practitioner, or be trained by the Qualified SWPPP Practitioner.

Table 2 – Visual Inspection Schedule7
Risk Level Weekly
Pre-Qualifying
Precipitation
Event
During Qualifying
Precipitation
Event
Post-Qualifying
Precipitation
Event
1 X X X X
2 X X X X
3 X X X X
III.C.2. Dischargers shall conduct weekly visual inspections to ensure that BMPs are properly installed and maintained. A pre-, during, or post-qualifying precipitation event inspection also satisfies the weekly visual inspection requirement.

III.C.3. Dischargers shall have a QSP conduct a pre-Qualifying Precipitation Event inspection within 72 hours prior to any weather pattern that is forecasted to have a 50 percent or greater chance of 0.5 inches or more in a 24-hour period.

Precipitation forecast information shall be obtained from the National Weather Service Forecast Office (e.g., by entering the zip code of the project’s location at https://www.weather.gov/) and shall be included as part of the inspection checklist weather information. If extended forecast precipitation data (greater than three days) is available from the National Weather Service, the pre- precipitation event inspection may be done up to 120 hours in advance. The pre- Qualifying Precipitation Event inspection shall include an inspection of the following:
a. All stormwater drainage areas to identify leaks, spills, or uncontrolled pollutant sources and when necessary, implement appropriate corrective actions to control pollutant sources.
b. All BMPs to identify whether they have been properly implemented in accordance with the SWPPP, and when necessary, implement appropriate corrective actions to control pollutant sources.
c. All stormwater storage and containment areas to detect leaks and check for available capacity to prevent overflow.

III.C.4. Dischargers shall conduct visual inspections at least once every 24-hour period during Qualifying Precipitation Events. Qualifying Precipitation Events are 7 This table is limited to routine weekly inspections and Qualifying Precipitation Event related inspections. Other visual inspections may be required under this Permit and are described in the applicable sections.

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NPDES No. CAS000002
ATTACHMENT D D-10
extended for each subsequent 24-hour period forecast to have at least 0.25 inches of precipitation.

III.C.5. Dischargers shall conduct post-Qualifying Precipitation Event visual inspections within 96 hours after each Qualifying Precipitation Event if 0.5 inches or more precipitation is measured during the duration of the Qualifying Precipitation Event using the onsite rain gauge. The inspection is to:
a. Identify if BMPs were adequately designed, implemented, and effective; b. Identify BMPs that require repair or replacement due to damage; and c. Identify additional BMPs that need to be implemented and revise the SWPPP accordingly.

III.C.6. Dischargers shall conduct visual inspections during scheduled site operating hours.

III.C.7. For each required inspection, dischargers shall develop and complete an inspection checklist that, at a minimum includes:
a. Inspection type (weekly, pre-precipitation, daily precipitation, or post- precipitation event);
b. Inspection date and time the inspection was conducted; c. Weather information, including the presence or absence of precipitation, an estimate of the beginning of the Qualifying Precipitation Event, duration of the event, date of the end of the Qualifying Precipitation Event, and the amount of precipitation in inches;
d. Site information, including stage of construction, activities completed since last inspection, and approximate area of the site exposed; e. A description of any BMPs evaluated and any deficiencies noted, including those that may have resulted in the release of non-visible pollutants; f. A list of BMPs inspected, including erosion controls, sediment controls, chemical and waste controls, and non-stormwater controls; g. Report of the presence of any floating and suspended materials, odors, discolorations, visible sheens, and any sources of pollutants in discharges and contained stormwater;
h. Any corrective actions required, including any necessary changes to the SWPPP and the associated implementation dates;
i. Photographs of areas of concern and the QSP’s description of the problem, if any; and
j. Inspector’s name, title, and certification, if any.

III.D. Water Quality Monitoring Requirements
Dischargers shall collect samples of discharges, based on their Risk Level in accordance with Table 3 and the requirements below, to monitor water quality and ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-11
assess compliance with the requirements of this General Permit. Samplers shall be the QSD, QSP, or be trained by the QSP.

Table 3 – Sample Collection Schedule
Risk Level
Stormwater Discharge
Sample Collection
(as applicable)
Receiving Water
Sample Collection
(as applicable)
Non-Visible
Sample Collection
(as applicable)
1 Not Applicable Not Applicable X
2 X Not Applicable X
3 X X
(Post-exceedance) X
III.D.1. Risk Level 2 and 3 Stormwater Discharge Monitoring Requirements III.D.1.a. Risk Level 2 and 3 dischargers shall collect stormwater grab samples, from all discharge locations incorporating runoff from project construction sites8, during discharge and within site operating hours. The grab samples shall be representative of the discharge flow and characteristics.

III.D.1.b. Risk Level 2 and 3 dischargers shall obtain one sample from each discharge location per 24-hour period of each Qualifying Precipitation Event, during active discharge.

III.D.1.c. Risk Level 2 and 3 dischargers shall collect samples of stored or contained stormwater during discharge from the impoundment, in accordance with Attachment J.

III.D.1.d. Risk Level 2 and 3 dischargers shall analyze all samples for:
i. pH and turbidity (refer to Order, Section IV.C.3.c and d); and ii. Any additional parameter required by the Regional Water Board.

III.D.1.e. Risk Level 2 and 3 dischargers may sample run-on from surrounding areas if there is reason to believe run-on may contribute to exceedance of numeric action levels and/or numeric effluent limitations.

III.D.2. Risk Level 3 Receiving Water Monitoring Requirements III.D.2.a. Risk Level 3 dischargers who discharge directly into receiving waters are also required to monitor that receiving water if sampling results from the discharge monitoring location meets either of the following conditions:
i. pH value falls outside of the range of 6.0 and 9.0 pH units; or ii. Turbidity exceeds 500 NTU.
8 The Glossary definition of ‘site’ applies here, i.e., The area where the construction activity is physically located or conducted, including staging, storage, and access areas.

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ATTACHMENT D D-12
III.D.2.b. Receiving water monitoring does not apply if run-on from a forest fire or any other natural disaster caused the stormwater results to fall outside the pH range or exceed the turbidity value.

III.D.2.c. Risk Level 3 dischargers required to conduct receiving water monitoring shall collect samples as follows:
i. Collect, at minimum, one upstream receiving water sample from an accessible and safe location that is:

1. Representative of the receiving water;

2. As close as possible to the discharge location; and

3. Upstream from the discharge location.
ii. Collect, at minimum, one downstream receiving water sample from an accessible and safe location that is:

1. Representative of the receiving water;

2. As close as possible to the discharge location; and

3. Downstream from the discharge location.

III.D.2.d. Risk Level 3 dischargers shall analyze the samples for the parameter that triggered this monitoring (either pH or turbidity, or both).

III.D.2.e. Risk Level 3 dischargers shall collect the samples once every 24-hour period of the Qualifying Precipitation Event.

III.D.2.f. Risk Level 3 dischargers shall specify the specific locations where samples were collected, date and time of sample collection, as well as constituents analyzed.

III.D.2.g. The Regional Water Board delegate may require, in writing, that the Risk Level 3 discharger continue to sample the receiving water for the parameter that required this monitoring (pH and/or turbidity) after the Qualifying Precipitation Event ends.

III.D.3. Non-Visible Pollutant Monitoring Requirements
III.D.3.a. Dischargers shall implement sampling and analysis requirements to monitor non-visible pollutants when there is:
i. Evidence of pollutant releases that are not visually detectable in stormwater discharges; and
ii. Releases of substances which could cause or contribute to an exceedance of water quality objectives in the receiving waters.

III.D.3.b. Dischargers are required to conduct sampling and analysis for non-visible pollutants identified in the SWPPP or otherwise known to be on site, only when the pollutants may be discharged due to failure to implement BMPs, a container spill or leak, or a BMP breach, failure, or malfunction.

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III.D.3.c. Dischargers shall collect at least one sample, within 8 hours, from each discharge location hydraulically down-gradient from the observed triggering event or condition.

III.D.3.d. Dischargers shall continue to collect at least one sample per applicable discharge location for each 24-hour period that there is discharge, until the necessary corrective actions are completed to control further discharge of the pollutant.

III.D.3.e. Dischargers are not required to sample if one of the conditions described in Section III.D.3.b above (e.g., breach or spill) occurs and, prior to discharge, the material containing the pollutant is fully remediated or removed; and BMPs to control the pollutant are implemented, maintained, or replaced as necessary.

III.D.3.f. Dischargers shall analyze samples in the field or submit them to a laboratory as specified in Section III.F of this Attachment for analysis of all non-visible pollutants suspected to be present in the discharge, including applicable TMDL-specific pollutants listed in Table H-2 in Attachment H.

III.E. Sample Collection and Handling Instructions
III.E.1. Dischargers shall:
a. Identify applicable parameters that require laboratory analysis for each stormwater discharge location (pH and turbidity are typically analyzed with field meters).
b. Request the laboratory provide the appropriate number of sample containers, types of containers, sample container labels, blank Chain of Custody forms, and sample preservation instructions.
c. Use the appropriate sample shipping method to the laboratory. The laboratory should receive samples within 48 hours of the physical sampling (unless otherwise required by the laboratory to meet all method hold times). The options are to either deliver the samples to the laboratory, arrange to have the laboratory pick them up, or ship them overnight to the laboratory. d. Use only the sample containers provided/specified by the laboratory to collect and store samples. Use of any other type of containers could cause sample contamination.
e. Prevent sample contamination by not touching or putting anything into the sample containers before collecting stormwater samples. f. Not overfill sample containers. Overfilling can change the analytical results. g. Secure each sample container cap without stripping the cap threads. h. Label each sample container. The label shall identify the date and time of sample collection, the person taking the sample, and the sample collection location or discharge point. The label should also identify any sample containers that have been preserved.

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i. Carefully pack the sample container into an ice chest or refrigerator to prevent breakage and maintain temperature during shipment; frozen ice packs or ice is placed into the shipping container to keep the sample close to 4° C (39° F) until arriving at the laboratory (do not freeze samples). j. Complete a Chain of Custody form with each set of samples. The Chain of Custody form shall include the discharger’s name, address, and phone number, identification of each sample container and sample collection point, person collecting the samples, the date and time each sample container was filled, the analysis that is required for each sample container, and both the signatures of the persons relinquishing and receiving the sample containers.

III.E.2. The Discharger shall designate and train personnel for the collection, maintenance, and shipment of samples in accordance with the above sample protocols and laboratory-specific practices.

III.E.3. Dischargers shall perform all sampling and preservation protocols in accordance with the 40 Code of Federal Regulations Part 136 and the current edition of "Standard Methods for the Examination of Water and Wastewater" (American Public Health Association).9
III.E.4. Dischargers may refer to the Surface Water Ambient Monitoring Program’s (SWAMP) Quality Assurance Program Plan (QAPrP) for more information on sampling collection and analysis.10
III.F. Analytical Methods Requirements
III.F.1. Dischargers shall refer to Table 4 for applicable test methods, detection limits, and reporting units.
9 Unless other test procedures have been specified in this General Permit or by the Water Boards.
10 Additional information regarding the SWAMP QAPrP can be found at:
<https://www.waterboards.ca.gov/water_issues/programs/swamp/quality_assurance. html#qaprp>. [as of October 20, 2020]
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Table 4 - Test Methods, Detection Limits and Reporting Units Parameter Test Method Discharger
Type
Method
Detection
Limit
Reporting
Units
pH
Field test with calibrated
portable instrument using
U.S. EPA approved
procedures
Risk Level
2 and 3 0.2 pH units
Turbidity
U.S. EPA 0180.1 and/or
field test with calibrated
portable instrument
Risk Level
2 and 3 1 NTU
Non-Visible
Pollutant
Parameter(s)
U.S. EPA-approved test
method for the specific
pollutant parameter
All Risk
Levels
Dependent
on the test
method
Dependent
on the test
method
III.F.2. All monitoring instruments and equipment shall be calibrated and maintained in accordance with manufacturers' specifications to ensure accurate measurements. Additionally, records of calibration shall be retained for at least three years and made available upon request.

III.F.3. Risk Level 2 and 3 dischargers shall perform pH analysis on-site with a calibrated pH meter using a U.S. EPA acceptable test method.

III.F.4. Risk Level 2 and 3 dischargers shall perform turbidity analysis using a calibrated turbidity meter (turbidimeter), either on-site or at a State Water Board Environmental Laboratory Accreditation Program (ELAP)-accredited laboratory.

Acceptable test methods include Standard Method 2130 B or U.S. EPA Method 180.1.

III.F.5. All analyses of laboratory-analyzed parameters shall be sent to and conducted at a laboratory recognized by the State Water Board Environmental Laboratory Accreditation Program (ELAP), with the exception of field analysis conducted by the discharger for turbidity and pH.

III.F.6. All dischargers shall assign a value of zero (0) for all non-visible pollutant analytical results less than the minimum level (reporting limit), as reported by the laboratory, used in calculations required by this permit (e.g., numeric action level and numeric effluent limitation exceedance determinations), so long as a sufficiently sensitive test method was used as evidenced by the reported method detection limit and minimum level.

III.G. Exceedance Response Requirements11
III.G.1. Dischargers are subject to the applicable numeric action levels and/or numeric effluent limitations based on their Risk Level as shown in Table 5 below. 11 Terms including, but not limited to, numeric action level, numeric effluent limitation, and exceedances are defined in Attachment B of this General Permit.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-16
Table 5 - Numeric Action Levels and Numeric Effluent Limitations Parameter Discharger Type Numeric Action
Level
Numeric Effluent
Limitation
pH Risk Level 2 and 3 Lower = 6.5
Upper = 8.5 Not Applicable
Turbidity Risk Level 2 and 3 250 NTU Not Applicable
TMDL-related
Pollutant
Responsible
Dischargers with a
project of any Risk
Level
Refer to Table H-2
in Attachment H
Refer to Table H-2
in Attachment H
III.G.2. For pH and turbidity, the discharger shall use the field meter readings obtained from each discharge location per day of discharge to determine if there has been an exceedance of the numeric action levels.

III.G.3. Whenever analytical results indicate that the discharge is below the lower pH value, above the upper pH value, exceeds the turbidity value, or exceeds an applicable TMDL-related numeric action level or numeric effluent limitation, dischargers shall determine the source(s) of the pollutant and immediately implement corrective actions to:
a. Meet Best Available Technology Economically Achievable and Best Conventional Pollutant Control Technology requirements in 40 Code of Federal Regulations §§ 450.21 through 450.2312; and
b. Reduce or prevent pollutants in stormwater and authorized non-stormwater discharges from causing further exceedances.

III.G.4. Dischargers shall iterate corrective actions until the discharge is in compliance with the applicable numeric action level(s).

III.G.5. The source evaluation shall be kept with the SWPPP and specifically address what corrective actions were taken or will be taken and provide a schedule for their completion.

IV. REPORTING REQUIREMENTS
IV.A. Visual Inspections
Dischargers shall keep all completed inspection checklists and related documentation with the SWPPP on-site or electronically. 12 United States Environmental Protection Agency, Construction and Development Effluent Limitation Guidelines §§ 450.21 through 450.23, <https://www.ecfr.gov/current/title-40/chapter-I/subchapter-N/part-450/subpart- B?toc=1> [as of June 28, 2022].

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-17
IV.B. Water Quality Monitoring
IV.B.1. Risk Level 2 and 3 Stormwater Discharge Monitoring Reporting IV.B.1.a. Risk Level 2 and 3 dischargers shall electronically submit through SMARTS all field sampling results within 30 days of the completion of the precipitation event or within 10 days if the field sampling results demonstrate the exceedance of the pH, and/or turbidity numeric action levels.

IV.B.1.b. Risk Level 2 and 3 dischargers that exceeded the pH and/or turbidity numeric action levels shall prepare a Numeric Action Level Exceedance Report when requested, in writing, from a Regional Water Board delegate and shall submit and certify each Numeric Action Level Exceedance Report through SMARTS within 30 days of receiving the written request, in accordance with Section IV of this General Permit’s Order.

IV.B.1.c. The Numeric Action Level Exceedance Report shall include:
i. The analytical method(s), method reporting unit(s), and method detection limit(s) for each parameter;
ii. The date, place, time of sampling, visual inspections, and/or measurements, including precipitation; and
iii. An assessment of the existing BMPs associated with the sample that exceeded the numeric action level, a description of each corrective action taken including photographs, and date of implementation.

IV.B.1.d. Risk Level 2 and 3 dischargers that prepared a Numeric Action Level Exceedance Report shall retain a copy of the report for a minimum of three years after the date the exceedance report is certified and submitted.

IV.B.2. Risk Level 3 Receiving Water Monitoring Reporting IV.B.2.a. Risk Level 3 dischargers shall electronically submit all receiving water sample results through SMARTS within 10 days of a precipitation event.

IV.B.3. Non-Visible Pollutant Monitoring Reporting
IV.B.3.a. All dischargers that conducted non-visible pollutant monitoring shall electronically submit through SMARTS all field and/or analytical sampling results within 30 days after obtaining the analytical result or within 10 days after if the analytical results demonstrate the exceedance of an applicable TMDL-related numeric action level or numeric effluent limitation or Basin Plan parameter.

IV.B.3.b. All dischargers that exceeded an applicable TMDL-related numeric action level shall prepare a Numeric Action Level Exceedance Report when requested, in writing, from a Regional Water Board delegate and shall submit and certify each Numeric Action Level Exceedance Report through SMARTS within 30 days of receiving the written request, in accordance with Section IV of this General Permit’s Order.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D D-18
IV.B.3.c. The Numeric Action Level Exceedance Report shall include:
i. The analytical method(s), method reporting unit(s), and method detection limit(s) for each parameter;
ii. The date, place, time of sampling, visual inspections, and/or measurements, including precipitation; and
iii. An assessment of the existing BMPs associated with the sample that exceeded the numeric action level, a description of each corrective action taken including photographs, and date of implementation.

IV.B.3.d. All dischargers that prepared a Numeric Action Level Exceedance Report shall retain a copy of the report for a minimum of three years after the date the exceedance report is certified and submitted.

IV.B.3.e. All dischargers that exceed an applicable TMDL-related numeric effluent limitation shall comply with the water quality-based corrective action requirements in Section VI.Q of the Order.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-1
ATTACHMENT D.1

RISK DETERMINATION WORKSHEET

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCIATED

WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)
The Risk Determination Worksheet in this Attachment serves as guidance for construction stormwater dischargers and may be used to manually calculate the site- specific risk of a construction project. Dischargers are required to submit risk information using the Stormwater Multiple Application and Report Tracking System (SMARTS) as part of filing a Notice of Intent for coverage under the Construction Stormwater General Permit.

Dischargers may use SMARTS to auto-populate values for the soil erodibility factor (K factor), length-slope factor (LS factor), and the receiving water risk (the risk sediment poses to receiving waters) based on the provided latitude and longitude coordinates for the project. SMARTS relies on the same data as the GIS map method, which dischargers can use to confirm the auto-populated values. Dischargers may alternatively use the individual method, a site-specific analysis, to determine the K factor, LS factor, and receiving water risk where GIS data may not accurately reflect the site’s characteristics.

Dischargers may use a combination of the GIS map method or individual method to calculate the K factor, LS factor, sediment risk, and receiving water risk in steps 1 and 2, depending on which method is judged to be the most accurate for the site.

SMARTS will automatically determine the combined Risk Level based on the entered information.

Instructions:

Step 1 – Determine sediment risk via one of the following options:
· GIS Map Method - EPA Rainfall Erosivity Calculator & GIS Map · Individual Method - EPA Rainfall Erosivity Calculator & Individual Data Step 2 – Determine receiving water risk via one of the following options:
· GIS Map Method - GIS Map of Sediment-Sensitive Watersheds · Individual Method - Provided Sediment Impaired Water Bodies Step 3 – Determine combined Risk Level
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-2
Step 1 – Sediment Risk Worksheet
The Construction Stormwater General Permit requires dischargers to calculate sediment risk by multiplying the rainfall erosivity (R), soil erodibility (K), and length-slope (LS) factors. Determine the values for each of the factors and use the table below to assess the site-specific sediment risk for the construction project. a. Rainfall Erosivity (R) Factor
Analyses of data indicated that when factors other than rainfall are held constant, soil loss is directly proportional to a rainfall factor composed of total storm kinetic energy (E) times the maximum 30-minute intensity (I30) (Wischmeier and Smith, 1958). The numerical value of R is the average annual sum of EI30 for storm events during a rainfall record of at least 22 years. "Isoerodent" maps were developed based on R values calculated for more than 1000 locations in the Western U.S.

A guide for the U.S. EPA Rainfall Erosivity Factor Calculator (https://www.waterboards.ca.gov/water_issues/programs/stormwater/smarts/constru ction/docs/rfactor_guide.pdf) is available to dischargers to assist with calculating the site-specific R factor.

R Factor Value = ______________
b. Soil Erodibility (K) Factor
The soil erodibility (K) factor represents: (1) susceptibility of soil or surface material to erosion, (2) transportability of the sediment, and (3) the amount and rate of runoff given a particular rainfall input, as measured under a standard condition. Fine- textured soils that are high in clay have low K values (about 0.05 to 0.15) because the particles are resistant to detachment. Coarse-textured soils, such as sandy soils, also have low K values (about 0.05 to 0.2) because of high infiltration resulting in low runoff even though these particles are easily detached. Medium-textured soils, such as a silt loam, have moderate K values (about 0.25 to 0.45) because they are moderately susceptible to particle detachment and they produce runoff at moderate rates. Soils having a high silt content are especially susceptible to erosion and have high K values, which can exceed 0.45 and can be as large as 0.65. Silt-size particles are easily detached and tend to crust, producing high rates and large volumes of runoff.

A soil erodibility nomograph is provided on page 4 to assist the discharger with determining the site-specific K factor.

K Factor Value = _____________
c. Length-Slope (LS) Factor
The effect of topography on erosion is accounted for by the LS factor, which combines the effects of a hillslope-length factor, L, and a hillslope-gradient factor, S.

Generally speaking, as hillslope length and/or hillslope gradient increase, soil loss increases. As hillslope length increases, total soil loss and soil loss per unit area increase due to the progressive accumulation of runoff in the downslope direction.

As the hillslope gradient increases, the velocity and erosivity of runoff increases.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-3
A length-slope table is provided on page 5 to assist the discharger with estimating the weighted LS factor for the site prior to construction.

LS Factor Value = ____________
d. Watershed Erosion Estimate
Estimate watershed erosion by multiplying the R, K, and LS factors, then use the table below to determine the site-specific sediment risk for the project.

Watershed Erosion Estimate (tons/acre) = R x K x LS = ____________ Watershed Erosion Estimate (tons/acre) Site-Specific Sediment Risk Less than 15 tons/acre Low
Greater than or equal to 15 tons/acre and less
than 75 tons/acre Medium
Greater than or equal to 75 tons/acre High
Site-specific Sediment Risk (High, Medium, or Low) = ____________ e. Sediment Risk GIS Map Method
In addition to the U.S. EPA Rainfall Erosivity Factor Calculator, State Water Board staff has prepared map tools to assist dischargers with estimating site-specific K and LS factors. Dischargers may use the map tools instead of manually determining the K and LS factors using the nomograph on page 4 and tables on page 5. Additionally, SMARTS is equipped with an auto-populate feature that can generate K and LS factors given the project latitude and longitude coordinates.

K Factor Map
(https://www.waterboards.ca.gov/water_issues/programs/stormwater/docs/constper mits/guidance/k_factor_map.pdf)
LS Factor Map
(https://www.waterboards.ca.gov/water_issues/programs/stormwater/docs/constper mits/guidance/ls_factor_map.pdf)
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-4
Soil Erodibility (K) Factor Nomograph
The K factor can be determined by using the nomograph method, which requires that a particle size analysis (ASTM D-422)1,2 be conducted to determine the percentages of sand, very fine sand, silt, and clay. Use the figure below to determine the appropriate K factor value.

The figure above is the Erickson triangular nomograph used by the USDA to determine the K factor for a soil based on its texture (percent silt plus very fine sand, percent sand, percent organic matter, soil structure, and permeability). 1 ASTM D-422 is the standard test method used for the quantitative determination of the distribution of particle sizes in soils.
2 Environmental Protection Agency, American Society for Testing and Materials (ASTM) Standards, <https://www.epa.gov/sites/default/files/2020-01/documents/sedc_2004- 2005_append.pdf> [as of June 22, 2022]

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-5
Nomograph from Erickson 1977, as referenced in Goldman et. al., 1986.

Length-Slope (LS) Factor Table for Construction Sites
To determine a construction site's specific LS factor locate the intercept of the site's Sheet Flow Length (ft) and Average Watershed Slope (percent). Table from Renard et. al., 1997.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-6
Step 2 – Receiving Water Risk Worksheet
Receiving water risk is based on whether a project drains to a water body or watershed that is sediment-sensitive. If the answer to either question below is “yes”, the project is considered a high receiving water risk. If the answer to both questions below is “no”, the project is considered a low receiving water risk.

1. Does the disturbed area discharge (either directly or indirectly) to a 303(d)-listed water body impaired by sediment? For help with identifying impaired water bodies, please refer to the 2020 – 2022 California Integrated Report (Clean Water Act Section 303(d) - 305(b) Report)
(https://www.waterboards.ca.gov/water_issues/programs/water_quality_assessment/ 2020_2022_integrated_report.html).

OR

2. Does the disturbed area discharge (either directly or indirectly) to a water body with designated beneficial uses of COLD, SPAWN, and MIGRATORY? For help with identifying designated beneficial uses, please refer to the appropriate Regional Water Quality Control Board Basin Plan below.

Region 1 – North Coast Basin Plan
(https://www.waterboards.ca.gov/northcoast/water_issues/programs/basin_plan/) Region 2 – San Francisco Bay Basin Plan
(https://www.waterboards.ca.gov/sanfranciscobay/basin_planning.html#2010basinplan) Region 3 – Central Coast Basin Plan
(https://www.waterboards.ca.gov/centralcoast/publications_forms/publications/basin_pla n/index.html)
Region 4 – Los Angeles Basin Plan
(https://www.waterboards.ca.gov/losangeles/water_issues/programs/basin_plan/) Region 5 – Central Valley Basin Plan3
(https://www.waterboards.ca.gov/centralvalley/water_issues/basin_plans/index.html) Region 6 – Lahontan Basin Plan
(https://www.waterboards.ca.gov/lahontan/water_issues/programs/basin_plan/index.htm l)
Region 7 – Colorado River Basin Plan
(https://www.waterboards.ca.gov/coloradoriver/water_issues/programs/basin_planning/) Region 8 – Santa Ana Basin Plan
(https://www.waterboards.ca.gov/santaana/water_issues/programs/basin_plan/index.ht ml)
3 The Central Valley Basin Plan lists the COLD beneficial use designation as part of the SPAWN and MIGRATORY beneficial uses. Waterbodies will be considered high-risk receiving waters if listed as SPAWN (COLD) and MIGRATORY (COLD).

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.1 D.1-7
Region 9 – San Diego Basin Plan
(https://www.waterboards.ca.gov/sandiego/water_issues/programs/basin_plan/index.ht ml)
Sediment-Sensitive Watershed GIS Map Method
State Water Board staff has prepared a High-Risk Receiving Watershed Map tool (https://www.waterboards.ca.gov/water_issues/programs/stormwater/docs/constpermits/ guidance/receivingwaterrisk.pdf) to assist dischargers with determining site-specific receiving water risk. Additionally, SMARTS is equipped with an auto-populate feature that can determine the receiving water risk based on the project latitude and longitude coordinates. Projects located in the watersheds highlighted in red are considered high- risk. Please note that the map option may not reflect the correct receiving watershed, lacking site-specific drainage information.

The discharger is responsible for identifying the appropriate receiving water. If the project does not discharge to the watershed as depicted on the High-Risk Receiving Watershed Map, please contact the appropriate Regional Water Quality Control Board.

Site-Specific Receiving Water Risk (High or Low) = __________ Step 3 – Combined Risk Level Matrix
The below matrix is used to determine the combined Risk Level of the project, factoring in both sediment risk and receiving water risk.

Combined Risk Level (1, 2, or 3) = _____________

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.2 D.2-1
ATTACHMENT D.2

PERMIT REGISTRATION DOCUMENT REQUIREMENTS

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES ASSOCIATED

WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES
(GENERAL PERMIT)
I. PERMIT REGISTRATION DOCUMENT REQUIREMENTS
All Linear Underground and Overhead Projects shall comply with the Permit Registration Document requirements in Attachments E, E.1, and E.2 of this General Permit. All traditional construction projects shall comply with Permit Registration Document requirements in this General Permit and this Attachment.

I.A. General Permit Registration Document Submittal Requirements Dischargers of stormwater associated with construction activity that result in the disturbance of one acre or more of land area shall apply for and obtain coverage under NPDES General Construction for Stormwater Discharges Associated with Construction and Land Disturbance Activities (General Permit). Any construction activity that is a part of a larger common plan of development or sale must also be covered under this General Permit, regardless of size. For example, if 0.5 acre of a 20-acre subdivision is disturbed by the construction activities of discharger A and the remaining 19.5 acres is to be developed by discharger B, discharger A must obtain this General Permit for the 0.5-acre site.

Other discharges from construction activities that are covered under this General Permit can be found in Section II of the Order of this General Permit.

It is the Legally Responsible Person’s responsibility to obtain coverage under this General Permit by electronically certifying and submitting complete Permit Registration Documents.

I.B. Fees
I.B.1. A discharger must submit the appropriate fee with its completed Notice of Intent application package. Fees are established through regulations adopted by the State Water Board every year.1 Fees are subject to change by regulation.

I.B.2. Where the fee is calculated based upon the total area of land disturbed (opposed to the total acreage of land owned), total acreage includes all areas anticipated to be disturbed throughout the duration of the project (e.g., 10 acres are scheduled 1 California Code of Regulations (CCR), Title 23, Division 3, Chapter 9. Waste Discharge Reports and Requirements, Article 1. Fees.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.2 D.2-2
to be disturbed the first year and 10 acres in each subsequent year for 5 years; the fees would be based upon 50 acres of total disturbance).

I.B.3. Dischargers that apply for and satisfy the Small Construction Rainfall Erosivity Wavier requirements shall pay the applicable fee.

I.C. Permit Registration Document Submittal Prior to Commencement of Construction
Dischargers proposing to conduct construction activities subject to this General Permit shall certify and submit Permit Registration Documents prior to the commencement of construction activity. Construction activity cannot commence until the WDID number is issued.

In all cases, except public emergencies (e.g., wildfire, flood), Permit Registration Documents must be completed and WDID number issued before construction can commence (refer to Section III.A.3 of the Order of this General Permit).

I.D. Submittal of Complete Permit Registration Documents All dischargers required to comply with this General Permit shall electronically certify and submit the required Permit Registration Documents, through the Stormwater Multiple Application and Report Tracking System (SMARTS). The discharger shall assure that all information in its Permit Registration Documents complies with the Homeland Security Act and other federal law addressing security in the United States.

The discharger shall submit completed Permit Registration Documents to obtain coverage under this General Permit. If any of the required items are incomplete or missing, the submittal will be rejected.

The State Water Board will process the application package in the order received and assign a WDID number upon receipt of a complete submittal. Permit coverage begins once a WDID number is assigned.

II. STANDARD PERMIT REGISTRATION DOCUMENTS
II.A. Notice of Intent
The Notice of Intent is a site-specific application to obtain coverage for discharges of stormwater and authorized non-stormwater from construction and land disturbance activities to waters of the United States. The application includes the entry of site information, contact information, and site-specific requirements.

II.B. Risk Level Determination
All dischargers are required to conduct a Risk Level Determination, where the site’s overall risk is separated into sediment risk and receiving water risk. The discharger must utilize either the Water Board’s standard risk determination (provided in ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.2 D.2-3
SMARTS), a site-specific risk determination, or a combination of the two as described in Attachment D.1 of this General Permit.

II.B.1. A standard risk determination, using the Geographic Information Systems (GIS) map method, includes utilizing the following:
i. U.S. EPA Rainfall Erosivity (R) Factor Calculator website; ii.. Sediment Risk Map tool; and
iii. High-Risk Receiving Watershed Map tool.

II.B.2. A site-specific risk determination, using the individual method, includes utilizing the following:
i. U.S. EPA Rainfall Erosivity (R) Factor Calculator website; ii. Manually calculated soil erodibility (K) and length-slope (LS) factors; and iii. 303(d) list of water bodies impaired for sediment.

II.B.3. The applicable beneficial uses for the receiving water are listed in the Regional Water Quality Control Board Basin Plan applicable to the site.

II.B.4. Sites that discharge to an unlisted receiving water that is tributary to a sediment- sensitive waterbody, within the Hydrologic Unit Code 10 (HUC 10) watershed scale, are considered high receiving water risk sites.

II.B.5. The discharger may use a combination of the standard and site-specific risk determination methods to calculate the soil erodibility (K), length-slope (LS) sediment risk, and receiving water risk factors.

II.B.6. The discharger shall calculate the site's sediment risk and receiving water risk during all phases of construction activity (e.g., demolition and pre-development site preparation, grading and land development, streets and utilities, vertical construction, final landscaping, and site stabilization). The construction start date begins with initial disturbance to land, including disturbances under previous landowners, and ends with final stabilization of the site.

II.B.7. SMARTS will assign the higher Risk Level to the entire site for any site spanning two or more planning watersheds.

II.B.8. Sites, parcels, or individual lots that are part of a larger plan of development shall include the larger plan of development in Risk Level determination. The discharger shall include this determination in the Permit Registration Documents submittal.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.2 D.2-4
II.B.9. Dischargers may request that the Regional Water Board revise the site-specific Risk Level determination values in SMARTS by providing the following information to the Regional Water Board:
i. A site-specific soils test (ASTM D-422)2,3 certified by an accredited Materials Testing Laboratory and reviewed by a QSD to determine the K factor used in the revised Risk Level determination. The soil testing must include the soil classification method used (e.g., Unified Soil Classification System); ii. Review of a site-specific survey or plan by a QSD to determine the LS factor used in the revised Risk Level determination; and
iii. A revised Risk Level determination manually calculated in accordance with Attachment D.1 of this General Permit.

II.C. Site-Specific Stormwater Pollution Prevention Plan, Drawings, and Map The Stormwater Pollution Prevention Plan (SWPPP) (including site-specific drawings and map) is a site-specific document developed for implementation of this General Permit. The SWPPP shall be developed by a Qualified SWPPP Developer and certified and submitted by each discharger with the other Permit Registration Documents.

II.D. Additional Requirements
II.D.1. All dischargers, other than Linear Underground and Overhead Project dischargers or dischargers subject to the post-construction requirements of an existing NPDES Phase I or II MS4 permit, shall complete the post-construction calculations and upload post-construction plans and other supporting documentation as an attachment in SMARTS.

II.D.2. All dischargers, other than Linear Underground and Overhead Project dischargers, within a Phase I or II municipal separate storm sewer system permitted area, shall upload the following items in SMARTS:

II.D.2.a. An attachment or web-source containing the applicable NPDES Phase I or Phase II municipal separate storm sewer system permittee’s post- construction requirements; and
II.D.2.b. The post-construction plans and calculations submitted to or approved by the applicable NPDES Phase I or Phase II municipal separate storm sewer system permittee.
2 ASTM D-422 is the standard test method used for the quantitative determination of the distribution of particle sizes in soils.
3 Environmental Protection Agency, American Society for Testing and Materials (ASTM) Standards, <https://www.epa.gov/sites/default/files/2020-01/documents/sedc_2004- 2005_append.pdf> [as of June 22, 2022]
ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT D.2 D.2-5
II.D.3. Dischargers who are proposing to implement an Active Treatment System shall also certify and submit in SMARTS:

II.D.3.a. Complete Active Treatment System Plan in accordance with Attachment F at least 14 days prior to the planned operation of the Active Treatment System and a copy shall be available on-site during Active Treatment System operation;
II.D.3.b. System design and supporting documentation; and II.D.3.c. Proof that the system and/or Active Treatment System Plan was designed by a qualified Active Treatment System professional in accordance with Attachment F of this General Permit.

II.D.4. Dischargers who are proposing to implement passive treatment shall certify and submit in SMARTS:

II.D.4.a. Complete Passive Treatment Plan in accordance with Attachment G of this General Permit at least 14 days prior to the planned operation of the passive treatment system and a copy shall be available on-site during operation; II.D.4.b. System design and supporting documentation; and II.D.4.c. Proof that the Passive Treatment Plan and/or system was designed by an appropriate licensed professional (see Attachment G of this General Permit).

II.D.5. Dischargers who are proposing an alternate Risk Justification shall include:

II.D.5.a. Soil type identification through an accredited Materials Testing Laboratory analysis and reviewed by a QSD; and
II.D.5.b. Review of a site-specific slope survey or plan by a QSD to determine the LS factor used in the revised Risk Level determination.

II.E. Certification of Submitted Documents
The Legally Responsible Person shall certify and submit all Permit Registration Documents required by this General Permit through SMARTS. The discharger’s Legally Responsible Person shall have a signed original Electronic Authorization Form on file with the State Water Board for each organization in SMARTS.

II.F. Exceptions to Standard Permit Registration Document Requirements Construction sites with a valid Small Construction Rainfall Erosivity Wavier are not required to submit a SWPPP (including site-specific drawings and map).

II.G. Assistance
Dischargers and discharger representatives may email the State Water Board, Stormwater Help Desk, at [email protected], to answer questions.

ORDER WQ 2022-0057-DWQ
NPDES No. CAS000002
ATTACHMENT E E-1

ATTACHMENT E

LINEAR UNDERGROUND AND OVERHEAD PROJECT REQUIREMENTS

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES)

GENERAL PERMIT FOR STORMWATER DISCHARGES

ASSOCIATED WITH CONSTRUCTION AND LAND DISTURBANCE ACTIVITIES (GENERAL PERMIT)
I. LINEAR UNDERGROUND AND OVERHEAD PROJECT BASELINE

REQUIREMENTS
Linear underground and overhead projects are identified as one of three types of risk (Type 1, 2, and 3) based on the project area or segment’s threat to water quality. Risk Types for linear projects are determined through SMARTS and clarified in Attachment E.1 of this General Permit when obtaining permit coverage. Risk Type 1, 2, and 3 dischargers shall implement the following minimum best management practices to reduce or prevent pollutants in construction stormwater discharges, and comply with monitoring and reporting requirements. If a requirement in this Attachment does not specify a specific Risk Type, then the requirement applies to Risk Type 1, 2, and 3 dischargers.

II. MINIMUM BEST MANAGEMENT PRACTICES
II.A. Good Site Management "Housekeeping"
II.A.1. Dischargers shall implement good site management measures (i.e., "housekeeping") for construction materials on a linear project site that could potentially be a threat to water quality if discharged or exposed to stormwater. At a minimum, dischargers shall implement the following good housekeeping measures:
a. Identify and protect the products used and/or expected to be used, and the end products that are produced and/or expected to be produced from exposure to stormwater. This requirement does not apply to materials and equipment that are designed to be outdoors and exposed to environmental conditions (e.g., poles, equipment pads, cabinets, conductors, insulators, bricks);
b. Apply best management practices (BMPs) to erodible stockpiled construction materials (e.g., soil, spoils, fly-ash, stucco, hydrated lime) to prevent erosion and pollutant transport;
c. Store chemicals in watertight containers with secondary containment to prevent any spillage or leakage or store in a complete enclosed storage area;
d. Minimize exposure of construction materials to precipitation. This requirement does not include materials and equipment that are designed to ORDER WQ 2022-0057-DWQ
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be outdoors and exposed to environmental conditions (e.g., poles, equipment pads, cabinets, conductors, insulators, bricks); e. Implement BMPs to control the off-site tracking of sediment and loose construction and landscape materials; and
f. Implement BMPs to control the discharge of plastic materials and limit the use of plastic materials when more sustainable, environmentally friendly alternatives exist. Dischargers shall consider the use of plastic materials resistant to solar degradation where plastic materials are deemed necessary.

II.A.2. Dischargers shall implement good housekeeping measures for waste management, which, at a minimum to the extent feasible, shall consist of the following:
a. Minimize the discharge of pollutants from equipment and vehicle washing, wheel wash water, masonry wash waters, and other wash waters. Wash waters shall be captured and treated prior to discharge or disposed of at a permitted facility that can accept that waste, to mitigate impacts to water quality;
b. Provide containment (e.g., secondary containment) of sanitation facilities (e.g., portable toilets) to prevent discharges of pollutants to the stormwater drainage system or receiving water;
c. Clean or replace sanitation facilities and inspecting them regularly for leaks and spills;
d. Keep debris or trash in waste containers if it is subject to transport from the site by wind or runoff;
e. Cover waste disposal containers at the end of every business day and during a precipitation event;
f. Prevent discharges from waste disposal containers to the stormwater drainage system or receiving water (e.g., containers with solid bottoms and regular maintenance);
g. Contain and securely protect stockpiled waste material from wind and precipitation unless actively being used; and
h. Secure and contain concrete washout areas and other washout areas that may contain additional pollutants to minimize discharge into the underlying soil and onto the surrounding areas. Washout areas shall be covered prior to and during a precipitation event.

II.A.3. Dischargers shall implement good housekeeping for vehicle/equipment storage and maintenance, which shall consist of the following:
a. Contain fuel, grease, and oil to prevent them from leaking into the ground, storm drains, or surface waters;
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b. Place all equipment or vehicles, which are to be fueled, maintained, and stored in a designated area with BMPs installed; and
c. Clean leaks immediately and dispose of leaked materials properly in accordance with the law.

II.A.4. Dischargers shall implement good housekeeping for landscape materials, which, at a minimum, shall consist of the following:
a. Contain and protect stockpiled materials such as mulches and topsoil, or other erodible landscape materials, from wind and precipitations unless being actively used;
b. Contain packaged landscape materials (e.g., fertilizers) when they are not being actively used;
c. Discontinue the application of any erodible landscape material at least 2 days before a forecasted precipitation event as defined in Attachment B or during periods of precipitation; and
d. Apply erodible landscape material at quantities and rates according to manufacturer recommendations or based on written specifications by knowledgeable and experienced field personnel.

II.A.5. Dischargers shall implement good housekeeping measures on the linear construction site, and of site operations, to control aerial deposition of site materials. Such particulates can include, but are not limited to, metals, nutrients, organics, sediment, other particulates, and trash.

II.A.6. Dischargers shall document all housekeeping BMPs in the Stormwater Pollution Prevention Plan (SWPPP) that correspond to the nature and phase of the construction activities.

II.B. Non-Stormwater Management
II.B.1. Dischargers shall implement the following measures to control all non- stormwater discharges during construction, to the extent feasible:
a. Wash vehicles in such a manner as to prevent non-stormwater discharges to surface waters or municipal separate storm sewer system drainage systems;
b. Clean streets in such a manner as to prevent unauthorized non-stormwater discharges from reaching surface water or municipal separate storm sewer system drainage systems; and
c. Eliminate any non-stormwater discharges that are not specified in Section IV.A of this General Permit’s Order, Authorized Non-Stormwater Discharges.

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II.C. Preserve Existing Topsoil
II.C.1. Dischargers shall preserve existing topsoil, unless infeasible, through the following practices:
a. Stockpiling existing topsoil, or transferring topsoil to other locations, to deploy and reestablish vegetation prior to termination of coverage; and b. Stabilizing disturbed topsoil during construction.

II.C.2. Preserving existing topsoil is not required where the intended function of a specific area of the site dictates that the topsoil be disturbed or removed.1 II.D. Erosion Control
II.D.1. Dischargers shall implement the following practices to eliminate or minimize site erosion. Erosion control BMPs (with the exception of sprayed products) shall be available on-site, or at a nearby location (e.g., common lay-down yard), year- round with trained persons able to deploy the product under the direction of the Qualified SWPPP Practitioner:
a. Implement effective wind erosion controls;
b. Preserve existing vegetation;
c. Minimize the amount of soil exposed during construction activity; d. Minimize the disturbance of steep slopes;
e. Schedule earthwork to minimize the amount of disturbed area when feasible;
f. Immediately initiate stabilization for disturbed areas whenever earth disturbing has permanently ceased on any portion of the site, or temporarily ceased on any portion of the site and will not resume for a period exceeding 14 calendar days;2
g. Minimize soil compaction in areas other than where the intended function of a specific area dictates that it be compacted;
h. Reestablish vegetation or non-vegetative erosion controls as soon as practicable;
1 Examples may include the removal of topsoil containing invasive seedbanks, lack of space to stockpile topsoil, and sites that are designed to be highly impervious after construction with little to no vegetation intended to remain. 2 In arid, semiarid, and drought-stricken areas where initiating vegetative stabilization measures immediately is infeasible, alternative stabilization measures shall be employed as specified by the Regional Water Board. Stabilization shall be completed within a period of time determined by the Regional Water Board. In limited circumstances stabilization may not be required if the intended function of a specific area of the site necessitates that it remains disturbed.

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i. If feasible, divert up gradient run-on water from contacting areas of exposed soils disturbed by construction activities or convey run-on through the site in a manner that prevents erosion from areas of construction and does not compromise the effectiveness of erosion, sediment, and perimeter controls; j. Run-on water flowing onto a site from off-site areas may be separated from a site’s stormwater discharge to eliminate commingled contribution. Run-on diversion shall occur prior to entering an area affected by construction activity. Run-on flow diversion shall be conveyed through or around the construction activity in plastic pipe or an engineered conveyance channel in a manner that will not cause erosion due to flow diversion. Run-on combined with a site’s stormwater discharge is considered a stormwater discharge;
k. Limit the use of plastic materials when more sustainable, environmentally- friendly alternatives exist. Where plastic materials are deemed necessary, the discharger shall consider the use of plastic materials resistant to solar degradation;
l. Control stormwater and non-stormwater discharges to minimize downstream channel and bank erosion; and
m. Control peak flowrates and total volume of stormwater and authorized non- stormwater discharges to minimize channel and streambank erosion and scour in the immediate vicinity of discharge points.

II.D.2. Dischargers that stabilize soil using bonded-fiber matrices, hydromulches, spray tackifiers, or other land-applied products shall:
a. Apply the product according to the manufacturer’s instructions and guidance; and
b. Apply the product according to the manufacturer’s guidance to allow for ample cure time and to prevent treatment chemicals from being transported by runoff.

II.E. Sediment Controls
II.E.1. Dischargers shall implement the following site sediment controls:
a. Establish and maintain effective perimeter controls; b. Stabilize all construction entrances and exits to sufficiently control erosion and sediment discharges from the site;
c. Design, install, and maintain effective sediment controls to minimize the discharge of pollutants utilizing site-specific BMPs; and d. Design sediment basins and impoundments according to the California Stormwater Quality Association’s (CASQA) current Construction BMP ORDER WQ 2022-0057-DWQ
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Guidance Handbook3 and utilize outlet structures that withdraw water from the surface, unless infeasible. Linear project dischargers utilizing sediment basins shall complete installation prior to other land disturbance activities unless infeasible.

II.F. Additional Linear Underground and Overhead Project Type 2 and 3 Requirements
II.F.1. At Risk Type 2 and 3 sites, dischargers shall implement the following additional erosion and sediment control BMPs for areas under active construction:4 a. Design and construct cut and fill slopes in a manner to ensure slope stability and to minimize erosion including, but not limited to, these practices:
i. Reduce continuous slope-length using terracing and diversions; ii. Reduce slope steepness; and
iii. Roughen slope surfaces with large cobble or track walking. b. Install linear sediment controls along the toe of the slope, face of the slope, and at the grade breaks of exposed slopes according to sheet flow lengths as shown in Table 1 until slope has reached Notice of Termination conditions for erosion protection. When infeasible to comply with Table 1 due to site-specific geology or topography, the Qualified SWPPP Developer shall include in the SWPPP a justification for the use of an alternative method to protect slopes from erosion and sediment loss.

Table 1 - Critical Slope and Sheet Flow Length Combinations for Linear Sediment Reduction Barrier
Slope Ratio (Vertical to Horizontal) Sheet flow length not to exceed ≤ 1:20 Per Qualified SWPPP Developer’s
specification.
> 1:20 to ≤ 1:4 35 feet
> 1:4 to ≤ 1:3 20 feet
> 1:3 to ≤ 1:2 15 feet
> 1:2 10 feet
3 California Stormwater Quality Association (CASQA), Construction BMP Handbook (January 2015), <https://www.casqa.org/sites/default/files/casqa-handbook- construction/master_hanbook_file_2015_sec.pdf> [as of May 20, 2021] (CASQA Construction BMP Handbook)
4 Active areas of construction are areas undergoing land surface disturbance and associated site areas included in the SWPPP. This includes construction activity during the preliminary phase, mass grading phase, streets and utilities phase, and the vertical construction phase.

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II.F.2. Risk Type 2 and 3 dischargers shall limit construction activity traffic to and from the project to entrances and exits that employ effective controls to prevent off- site tracking of sediment.

II.F.3. Risk Type 2 and 3 dischargers shall maintain and protect all storm drain inlets, perimeter controls, and BMPs at entrances and exits (e.g., tire wash off locations).

II.F.4. Risk Type 2 and 3 dischargers shall remove any excess sediment or other construction activity-related materials that are deposited on the impervious roads by vacuuming or sweeping prior to any precipitation event.

II.F.5. Risk Type 2 and 3 dischargers shall implement additional site-specific sediment controls upon written request by the Regional Water Boards when the implementation of the other requirements in this Section are determined to inadequately protect the site’s receiving water(s).

II.G. Surface Water Buffer5
II.G.1. Linear project dischargers shall provide and maintain natural buffers and/or equivalent erosion and sediment controls when a water of the United States is located within 50 feet of the site’s earth disturbances, unless infeasible.

II.G.2. Linear project dischargers shall comply with one of the following alternatives for any discharges to waters of the United States located within 50 feet of a site’s earth disturbances:
a. Provide and maintain a 50-foot undisturbed natural buffer, from the edge of the disturbed area to the top of bank;
b. Provide and maintain an undisturbed natural buffer that is less than 50 feet and is supplemented by erosion and sediment controls that achieve, in combination, the sediment load reduction equivalent to a 50-foot undisturbed natural buffer. The equivalent sediment load may be calculated using the Revised Universal Soil Loss Equation, Volume 2 (RUSLE2) model or another method approved by the Regional Water Board; or c. Implement erosion and sediment controls to achieve the sediment load reduction equivalent to a 50-foot undisturbed natural buffer when it is infeasible to provide and maintain an undisturbed natural buffer of any size.

The equivalent sediment load may be calculated using RUSLE2 or another method approved by the Regional Water Board.
5 The surface water buffer requirements apply to work above the top-of-bank or high- water level of waters of the United States. Work within a channel or streambed (water body-dependent construction), Clean Water Act § 404 projects with § 401 certification, and projects where no natural surface buffer exists (e.g., concrete channelization) are exempt from the requirements. All types of in-channel work may be regulated under Section 401 (Clean Water Act - Regional Boards), Section 404 (Clean Water Act - Army Corps of Engineers), or Section 1602 (California Fish and Game Code).

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II.H. Pesticide Application
Linear project dischargers shall only apply pesticides that have been authorized for use through California Department of Pesticide Regulation. The application of pesticides shall follow manufacturer’s guidance.

II.I. Demolition of Existing Structure
Linear project dischargers shall prevent demolition materials from being exposed to precipitation. Demolition materials should be covered with an impermeable barrier such as, but not limited to, plastic sheeting prior to precipitation to prevent known contaminants from being mobilized. Dischargers unable to cover demolished material that were not previously investigated or found to be absent of applicable pollutants in reportable quantities shall sample for any non-visible pollutants that may be in stormwater discharges that may be present such as, but not limited to, asbestos, leaded paint, or poly chlorinated biphenyls (PCBs)6.

II.J. Maintenance and Repair
II.J.1. Linear project dischargers shall begin maintaining, repairing, and/or implementing design changes (reviewing alternatives that have not been used yet) to BMPs within 72 hours of identification of failures or other short comings, and complete the changes as soon as possible, prior to the next forecasted precipitation event.

II.J.2. Linear project dischargers shall have a Qualified SWPPP Practitioner (QSP) verify all BMP maintenance and repairs were appropriately implemented during the next visual inspection following completion. The QSP may delegate BMP maintenance and repair verification to an appropriately trained delegate.

III. MONITORING REQUIREMENTS
III.A. General Requirements
Linear project dischargers shall implement the Construction Site Monitoring Program in compliance with this Section at the time of the commencement of construction activity and shall continue implementation until the project is complete and the project site is stabilized as defined in Section III.H in the Order.

The monitoring requirements of this Section are issued pursuant to Water Code § 13383 and specify monitoring requirements for linear project dischargers subject to this Order.
6 PCBs were used between January 1, 1950 and January 1, 1980 and should be considered to be potentially present in structures built during that timeframe. “Structure”, in this instance, shall have been constructed with floor space (such as a building).

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III.B. Monitoring Exceptions
III.B.1. Linear project dischargers shall conduct visual inspections and collect samples to meet the requirements of this Attachment. Dischargers are not required to physically conduct visual inspections or collect samples under the following conditions:
a. During dangerous weather conditions such as electrical storms, flooding, and high winds above 40 miles per hour;
b. Outside of scheduled site operating hours; or
c. When the linear project site is not accessible to personnel.

III.B.2. For linear project sites that are inactive, the discharger may reduce the visual inspection frequency and suspend sampling per Section III.G of the Order.

III.B.3. Linear project dischargers shall provide an explanation with supporting information for all missed visual inspections or sampling required by this Attachment, to be included in the Annual Report.

III.C. Visual Inspection Requirements
III.C.1. Linear project dischargers shall perform visual inspections, based on their Risk Type, in accordance with Table 2 below. The purpose of the visual inspections is to identify and record BMPs that need maintenance to operate effectively, that have failed, or that could fail to operate as intended. Except as specified in Section III.C.3 below, inspectors shall be the Qualified SWPPP Developer, Qualified SWPPP Practitioner, or be trained by the Qualified SWPPP Practitioner.

Table 2 – Visual Inspection Schedule7
Linear
Underground
and
Overhead
Project Type
Weekly
Pre-Qualifying
Precipitation
Event
During
Qualifying
Precipitation
Event
Post-
Qualifying
Precipitation
Event
1 X X X Not Applicable
2 X X X X
3 X X X X
III.C.2. Linear project dischargers shall conduct weekly visual inspections to ensure that BMPs are properly installed and maintained. A pre-, during, or post-qualifying precipitation event inspection satisfies the weekly visual inspection requirement. 7 This table is limited to routine weekly inspections and Qualifying Precipitation Event related inspections. Other visual inspections may be required under this Permit and are described in the applicable sections.

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III.C.3. Linear project dischargers shall have a QSP conduct a pre-Qualifying Precipitation Event inspection within 72 hours prior to any weather pattern that is forecasted to have a 50 percent chance of 0.5 inches or more in a 24-hour period. Precipitation forecast information shall be obtained from the National Weather Service Forecast Office (e.g., by entering the zip code of the project location at https://www.weather.gov/) and shall be included as part of the inspection checklist weather information. If extended forecast precipitation data (greater than three days) is available from the National Weather Service, the pre-precipitation event inspection may be done up to 120 hours in advance. The pre-Qualifying Precipitation Event inspection shall include an inspection of the following:
a. All stormwater drainage areas to identify leaks, spills, or uncontrolled pollutant sources and when necessary, implement appropriate corrective actions to control pollutant sources;
b. All BMPs to identify whether they have been properly implemented in accordance with the SWPPP and when necessary, implement appropriate corrective actions to control pollutant sources; and
c. All stormwater storage and containment areas to detect leaks and check for available capacity to prevent overflow.

III.C.4. Dischargers shall conduct daily visual inspections at least once every 24-hour period during Qualifying Precipitation Events. Qualifying Precipitation Events are extended for each subsequent 24-hour period forecast to have at least 0.25 inches of precipitation.

III.C.5. Risk Type 2 and 3 dischargers* shall conduct post-Qualifying Precipitation Event visual inspections within 96 hours after each Qualifying Precipitation Event if 0.5 inches or more precipitation is measured during the duration of the Qualifying Precipitation Event using the onsite rain gauge. The 96-hour time frame may include the two consecutive 24-hour periods with less than 0.25 inches forecast, which mark the end of the precipitation event. The inspection is to:
a. Identify if BMPs were adequately designed, implemented, and effective; b. Identify BMPs that require repair or replacement due to damage; and c. Identify any additional BMPs that need to be implemented and revise the SWPPP accordingly.

III.C.6. Linear project dischargers shall conduct all visual inspections during scheduled site operating hours.

III.C.7. For each required inspection, Linear project dischargers shall develop and complete an inspection checklist that, at a minimum includes:
* The July 22, 2022 draft Order was clear that this monitoring requirement applied to only Risk Type 2 and 3 dischargers. Change Sheet #2, which was circulated September 7, 2022, inadvertently did not reflect this limitation. The final Order has been corrected to reflect that this requirement applies only to Risk Type 2 and 3.

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a. Inspection type (weekly, pre-precipitation, daily precipitation, or post- precipitation event);
b. Inspection date and time the inspection was conducted; c. Weather information, including the presence or absence of precipitation, an estimate of the beginning of the Qualifying Precipitation Event, duration of the event, date of the Qualifying Precipitation Event, and the amount of precipitation in inches;
d. Site information, including stage of construction, activities completed since last inspection, and approximate area of the site exposed; e. A description of any BMPs evaluated and any deficiencies noted, including those that may have resulted in the release of non-visible pollutants; f. A list of the inspections of all BMPs inspected, including erosion controls, sediment controls, chemical and waste controls, and non-stormwater controls;
g. Report of the presence of any floating and suspended materials, odors, discolorations, visible sheens, and any sources of pollutants in discharges and contained stormwater;
h. Any corrective actions required, including any necessary changes to the SWPPP and the associated implementation dates;
i. Photographs of areas of concern and the QSP’s description of the problem, if any; and
j. Inspector’s name, title, and certification, if any.

III.D. Water Quality Monitoring Requirements
Linear project dischargers shall collect samples of discharges, based on their Risk Type, in accordance with Table 3 and the requirements below, to monitor water quality and assess compliance with the requirements of this General Permit.

Samplers shall be the Qualified SWPPP Developer, Qualified SWPPP Practitioner, or be trained by the Qualified SWPPP Practitioner.

Table 3 – Sample Collection Schedule
Linear
Undergroun
d and
Overhead
Project Risk
Type
Stormwater Discharge
Sample Collection
(when applicable)
Receiving Water
Sample Collection
(when applicable)
Non-Visible
Sample Collection
(when applicable)
1 Not Applicable Not Applicable X
2 X Not Applicable X
3 X X
(Post-exceedance) X
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III.D.1. Risk Type 2 and 3 Stormwater Discharge Monitoring Requirements III.D.1.a. Risk Type 2 and 3 dischargers shall collect stormwater samples from sampling locations at one or more discharge locations representative of the project’s construction activities, during discharge and within site operating hours. The samples shall be representative of the discharge flow and characteristics.