Agenda — Hemet City Council, September 10, 2024 (part 7 of 10)

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Order R8-2024-0001 (NPDES No. CAS618000) Page 90 of 320 Appendix 1
Santa Ana Regional MS4 Permit
Table 1.3: TMDLs Applicable to San Bernardino County Permittees Permittee
Nutrient TMDL for Dry
Hydrological conditions for
Big Bear Lake
Middle Santa Ana River Bacterial
TMDL
San Bernardino County X X
San Bernardino County Flood
Control District X X
City of Big Bear Lake X
City of Chino Hills X
City of Chino X
City of Colton
City of Fontana X
City of Grand Terrace
City of Highland
City of Montclair X
City of Ontario X
City of Rancho Cucamonga X
City of Redlands
City of Rialto X
City of San Bernardino
City of Upland X

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Appendix 2

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Order R8-2024-0001 (NPDES No. CAS618000) Page 92 of 320 Appendix 2
Santa Ana Regional MS4 Permit
Appendix 2

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR NUTRIENTS IN THE

NEWPORT BAY/SAN DIEGO CREEK WATERSHED
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into Newport Bay as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Nutrient TMDLs for the Newport Bay/San Diego Creek. The compliance deadline of December 31, 2012 specified in the Basin Plan has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of nutrients in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Nitrogen, Total
A. Total Nitrogen is the sum of nitrate (NO3), nitrite (NO2), ammonia, and organic nitrogen.

B. Daily Effluent Limitation – Discharges of runoff from MS4s into Reach 2 of San Diego Creek must not transport more than 5.5 pounds of total nitrogen per day to Newport Bay during non-storm conditions, subject to the following conditions:

1. This effluent limitation only applies to flows less than 25 cubic feet per second (cfs) and those flows above 25 cfs that are not the result of precipitation.

2. Flow must be measured in San Diego Creek at Culver Drive.

C. Winter Effluent Limitation – Discharges of runoff from MS4s into San Diego Creek must not transport more than 55,442 pounds of total nitrogen into Newport Bay during each wet season.

1. This effluent limitation applies to discharges between Oct 1 and Mar 31 of each year.

2. This effluent limitation applies to discharges where the mean daily flow rate in San Diego Creek is less than 50 cfs and to mean daily flow rates more than 50 cfs that are not the result of precipitation.

D. Summer Effluent Limitation – Discharges of runoff from MS4s into San Diego Creek must not transport more than 16,628 pounds of total nitrogen into Newport Bay during the dry season.

1. This effluent limitation applies to discharges between April 1 to September 30 of each year.

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II. WQBELs for Phosphorus, Total
A. Discharges of runoff from MS4s must not transport more than 2,960 pounds of total phosphorous per year into Newport Bay.

Table 2.1 Summary of Nutrients Effluent Limitations for Newport Bay Pollutant Ibs/year Ibs/day
Summer
Ibs/season
Oct. 1–Mar 31
Winter
Ibs/season
Apr. 1–Sep. 30
Total Nitrogen -- 5.5 16,628 55,442
Total
Phosphorus 2,960 -- -- --
III. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order R8-2024- 0001 (Order) and as shown in this section III of Appendix 2. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

C. Demonstrate that the Permittee’s MS4 discharge did not cause or contribute to an exceedance of the WQBEL, because the exceedance is the result of an authorized or exempt non-stormwater discharge specified in section IV.A.2 of the Order during a specific sampling event. The water quality characteristics must be based on the source specific water quality monitoring data from the authorized or conditionally exempt essential non-stormwater discharge or other relevant information documenting the characteristics of the specific non-stormwater discharge.

D. Demonstrate that all non-stormwater and all stormwater runoff up to and including the volume equivalent to the 85th percentile, 24-hour storm event is retained for the drainage area tributary to the applicable receiving waters. The runoff retention must occur according to an approved Watershed Management Plan under section XII of the Order and include ongoing monitoring and adaptive management.

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Santa Ana Regional MS4 Permit
E. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan. For reference, Total TMDL Allocations are summarized in Table 2.2.

Table 2.2 Summary of Nutrients Total TMDL Allocations for Newport Bay TMDL Targets Allocation
lbs/year
Summer Allocation
lbs/season
(April – Sept)
Winter Allocation
lbs/season
(Oct – Mar)
Newport Bay Total
Nitrogen -- 152,861 144,364
San Diego Creek Total
Nitrogen 14 -- --
Newport Bay Total
Phosphorous 62,080 -- --
Newport Bay Total
Phosphorous Combined
Waste Load Allocation
15,770 -- --
IV. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 3

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Regional MS4 Permit, Order R8-2024-0001
Appendix 3

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR FECAL COLIFORM IN

NEWPORT BAY
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by those Permittees discharging into Newport Bay as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Fecal Coliform TMDLs for Newport Bay.

The compliance deadline of December 30, 2014, for the REC1 beneficial use specified in the Basin Plan has passed. However, the compliance deadline of December 31, 2030, for the SHEL beneficial use has not passed. As of the date of issuance of this permit, a Time Schedule Order (R8-2019-0050) has been issued and that provides a time schedule to attain the REC1 WQBELs by December 6, 2023.

Permittees must carry out an effective portfolio of projects and programs for the control of fecal coliform in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Fecal Coliform for REC1
A. The geometric mean concentration of fecal coliform in Newport Bay must not exceed 200 organisms/100 milliliters (mL).

B. The geometric mean concentration of fecal coliform in Newport Bay must be calculated using a minimum of 5 representative samples of runoff taken per calendar month.

C. Of the representative samples taken, no more than 10% can exceed 400 organisms/100mL for any 30-day period.

II. WQBELs for Fecal Coliform for SHEL
A. By December 31, 2030, the monthly median of representative samples of fecal coliform in Newport Bay must not exceed 14 most probable number (“MPN”)/100 mL; and
B. Of the representative samples taken of fecal coliform, not more than 10% can exceed 43 MPN/100 ml.

III. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in this section III of Appendix 3. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

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A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

E. Demonstrate that all non-stormwater and all stormwater runoff up to and including the volume equivalent to the 85th percentile, 24-hour storm event is retained for the drainage area tributary to the applicable receiving waters. The runoff retention must occur according to an approved Watershed Management Plan under section XII of the Order and include ongoing monitoring and adaptive management.

F. Demonstrate that an alternative indicator (e.g., enterococci) in the Permittee’s MS4 discharge is below levels that are equivalent to a risk to human health less than 32 illnesses/1000 people.

G. Demonstrate, through an approved epidemiological study or quantitative microbial risk assessment (QMRA), that the risk to human health is less than 32 illnesses/1000 people.

IV. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 4

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Appendix 4

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR SEDIMENT IN THE

NEWPORT BAY/SAN DIEGO CREEK WATERSHED
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into Upper Newport Bay as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Sediment TMDLs for Upper Newport Bay/San Diego Creek Watershed. The compliance deadline of April 16, 2009 (10 years from the date of sediment TMDL approval by USEPA) specified in the Basin Plan has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of sediment in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Sediment
A. Discharges of sediment from MS4s to Newport Bay shall not exceed 2,500 tons per year, calculated as a 10-year running annual average.

B. Discharges of sediment from MS4s to San Diego Creek and its tributaries shall not exceed 2,500 tons per year, calculated as a 10-year running annual average.

II. Alternative WQBELs for Sediment
A. In lieu of compliance with the WQBELs in section I above, Permittees must alternatively achieve all the following:

1. Sediment in discharges from the Permittees’ MS4s must not alter the distribution of habitat types in the 700-acre Upper Newport Bay Ecological Reserve identified in Table 4.1 below by more than 1%.

Table 4.1: Baseline Distribution of Habitat Types in the Upper Newport Bay Ecological Reserve
Habitat Type Acres Permissible Change (acres)
Marine aquatic 210 2.1
Mudflat 214 2.14
Salt marsh 277 2.77
Riparian 31 0.31

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2. A minimum depth of 7 feet below mean sea level shall be maintained in the Unit 1 and 2 Sediment Basins in Upper Newport Bay.

3. All in-channel and foothill sediment control basins throughout the drainages in the watershed shall be maintained to have at least 50% of design capacity available prior to November 15 of each year. The Permittees shall submit a report by November 15 of each year certifying whether the sediment basins in the watershed have at least 50% capacity.

B. To demonstrate compliance with the above Alternative WQBELs for Sediment, the Permittees must perform monitoring as follows:

1. Conduct bathymetric and vegetation surveys of Newport Bay no less than once every three years, or as specified by the Executive Officer. This information will be used to evaluate compliance with the acreage and depth targets.

2. Conduct topographic and vegetation surveys of Upper Newport Bay at least every three years, or as specified by the Executive Officer. If monitoring for total sediment load in San Diego Creek at Jamboree Boulevard and Campus Drive (Site ID: SDMF05) shows that more than 62,500 tons of sediment were discharged to the Bay, the topographic and vegetation surveys shall be conducted to determine the amount of sediment deposition in the two in-Bay basins and the other marine aquatic habitat areas and to determine changes in the areal extent of the existing aquatic wildlife and endangered species habitat areas.

3. Submit an annual report via SMARTS by December 31 of each year providing the monitoring data and information collected by the Permittees, including the flow and suspended solids monitoring data, the scour studies, the bathymetric and vegetation surveys, (and any additional information collected). The monitoring shall be completed prior to July 1 of each year and this information shall be used to determine the maintenance requirements of all sediment basins in the watershed.

III. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order R8-2024- 0001 (Order) and as shown in this section III of Appendix 4. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

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B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

D. Demonstrate attainment of the Alternative WQBELs according to section II of Appendix 4.

F. Demonstrate that the Permittees have reduced the target annual average total sediment load in the watershed to 125,000 tons per year, thereby reducing the sediment load to Newport Bay to the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) of 62,500 tons per year and limiting sediment deposition in the drainages to approximately 62,500 tons per year.

The reduction shall be calculated as 10 year running average amount of suspended solids measured in San Diego Creek at Jamboree Boulevard and Campus Drive.

IV. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 5

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Order R8-2024-0001 (NPDES No. CAS618000) Page 103 of 320 Appendix 5
Santa Ana Regional MS4 Permit
Appendix 5

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR ORGANOCHLORINE

COMPOUNDS IN SAN DIEGO CREEK, UPPER AND LOWER NEWPORT BAY The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into Newport Bay and San Diego Creek as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Organochlorine Compounds TMDL for San Diego Creek, Upper and Lower Newport Bay, and Rhine Channel. The compliance deadline of December 31, 2020 specified in the Basin Plan has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of organochlorine compounds in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Chlordane
A. Discharges of runoff from MS4s must not transport more than 30.1 grams per year (g/year) of chlordane into Upper Newport Bay.

B. Discharges of runoff from MS4s must not transport more than 11 g/year of chlordane into Lower Newport Bay
C. Discharges of runoff from MS4s must not transport more than 0.1 gram of chlordane into the Rhine Channel per year.

II. WQBELs for Total DDT
A. Discharges of runoff from MS4s must not transport more than 51.8 g/year of total DDT into Upper Newport Bay.

B. Discharges of runoff from MS4s must not transport more than 19.1 g/year of total DDT into Lower Newport Bay.

C. Discharges of runoff from MS4s must not transport more than 128.3 g/year of total DDT into the San Diego Creek and its tributaries.

D. Discharges of runoff from MS4s must not transport more than 0.7 gram of total DDT into the Rhine Channel per year.

III. WQBELs for Dieldrin
A. Discharges of runoff from MS4s must not transport more than 4.45 g/year of Dieldrin into Lower Newport Bay.

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B. Discharges of runoff from MS4s must not transport more than 183.4 g/year of Dieldrin into the San Diego Creek and its tributaries.

C. Discharges of runoff from MS4s must not transport more than 0.13 gram of Dieldrin into the Rhine Channel per year.

IV. WQBELs for Total PCBs
A. Discharges of runoff from MS4s must not transport more than 29.8 g/year of total PCBs into Upper Newport Bay.

B. Discharges of runoff from MS4s must not transport more than 78.1 g/year of total PCBs into Lower Newport Bay.

C. Discharges of runoff from MS4s must not transport more than 4.1 grams of total PCB into the Rhine Channel per year.

V. WQBELs for Toxaphene
A. Discharges of runoff from MS4s must not transport more than 1.9 g/year of Toxaphene into the San Diego Creek and its tributaries.

Table 5.1: Summary of WQBELs by Receiving Waters for Organochlorine Compounds (Grams per Year)
Receiving
Waters
Total DDT
(g/year)
Chlordane
(g/year)
Total PCBs
(g/year)
Dieldrin
(g/year)
Toxaphene
(g/year)
San Diego
Creek and
Tributaries
128.3 -- -- 183.4 1.9
Upper
Newport Bay 51.8 30.1 29.8 -- --
Lower
Newport Bay 19.1 11.0 78.1 4.45 --
Rhine
Channel 0.7 0.1 4.1 0.13 --
VI. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in this section VI of Appendix 5. Processes used to analyze data and support demonstrations of compliance, as well as compliance

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monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

E. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan. For reference, Total TMDL Allocations are summarized in Table 5.2.

Table 5.2: Summary of Total TMDL Allocations for San Diego Creek, Upper and Lower Newport Bay, expressed on an annual basis.

Total Allocation (grams per year)
Waterbody Total DDT Toxaphene Chlordane Total PCBs
San Diego Creek and
Tributaries 396 6 -- --
Upper Newport Bay 160 -- 93 92
Lower Newport Bay 59 -- 34 241
VII. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and

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Reporting Program (MRP) in Attachment C of this Order.

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Appendix 6

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Appendix 6

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR THE DIAZINON &

CHLORPYRIFOS TMDL FOR SAN DIEGO CREEK AND UPPER NEWPORT BAY The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into Upper Newport Bay and its tributaries or San Diego Creek as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Diazinon & Chlorpyrifos TMDLs for San Diego Creek and Upper Newport Bay. The compliance deadline of December 1, 2007 specified in the Basin Plan has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of diazinon and chlorpyrifos in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. General
A. For Appendix 6, acute concentration shall mean the average concentration measured in samples collected over a 24-hour period.

B. For Appendix 6, chronic concentration shall mean the average concentrations measured in samples collected over a 96-hour period.

II. WQBELs for Chlorpyrifos
A. Discharges of Chlorpyrifos in runoff from MS4s into Upper Newport Bay and its tributaries shall not exceed the acute concentration of 18 nanograms per liter (ng/L).

B. Discharges of Chlorpyrifos in runoff from MS4s into Upper Newport Bay and its tributaries shall not exceed the chronic concentration of 8.1 ng/L.

C. Discharges of Chlorpyrifos in runoff from MS4s into San Diego Creek shall not exceed the acute concentration of 18 ng/L.

D. Discharges of Chlorpyrifos in runoff from MS4s into San Diego Creek shall not exceed the chronic concentration of 12.6 ng/L.

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Table 6.1: Summary of WQBELs (Maximum Concentrations) for Runoff from MS4 Permittees for Discharges of Chlorpyrifos into Upper Newport Bay and its Tributaries, and into San Diego Creek (ng/L)
Receiving Waters
Acute Concentration
(ng/L)
Chronic Concentration
(ng/L)
Upper Newport Bay 18 8.1
San Diego Creek 18 12.6
III. WQBELs for Diazinon
A. Discharges of Diazinon in runoff from MS4s into San Diego Creek shall not exceed the acute concentration of 72 ng/L.

B. Discharges of Diazinon in runoff from MS4s into San Diego Creek shall not exceed the chronic concentration of 45 ng/L.

Table 6.2: Summary of WQBELs (Maximum Concentrations) for Runoff from MS4 Permittees for Diazinon into Upper Newport Bay and its Tributaries, and into San Diego Creek (ng/L)
Receiving Waters
Acute Concentration
(ng/L)
Chronic Concentration
(ng/L)
San Diego Creek 72 45
IV. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8-2024- 0001 (Order) and as shown in this section IV of Appendix 6. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

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C. Demonstrate that the Permittee’s MS4 discharge did not cause or contribute to an exceedance of the WQBEL, because the exceedance is the result of an authorized or exempt non-stormwater discharge specified in section IV.A.2 of the Order during a specific sampling event. The water quality characteristics must be based on the source specific water quality monitoring data from the authorized or conditionally exempt essential non-stormwater discharge or other relevant information documenting the characteristics of the specific non-stormwater discharge.

The runoff retention must occur according to an approved Watershed Management Plan under section XII of the Order and include ongoing monitoring and adaptive management requirements.

E. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan. Total TMDL Allocations are summarized in Table 6.3. below.

Table 6.3: Summary of Total TMDL Allocations for Diazinon and Chlorpyrifos by Receiving Waterbody
Waterbody
Diazinon Chlorpyrifos
Acute (ng/L) Chronic
(ng/L) Acute (ng/L) Chronic (ng/L)
San Diego Creek 80 50 20 14
Upper Newport Bay - - 20 9
V. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 7

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Appendix 7

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR TOXIC POLLUTANTS (METALS) IN SAN DIEGO CREEK AND NEWPORT BAY
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into San Diego Creek and Newport Bay as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Toxic Pollutants (Metals) in San Diego Creek and Newport Bay. There are also specific WQBELs for Rhine Channel, a small, closed-ended navigation channel located in the western part of Newport Bay. These TMDLs were all effective upon promulgation by USEPA.

As indicated below, the WQBELs for copper discharges to Newport Bay shall be superseded by the WQBELs in Appendix 10 upon the effective date of the Copper TMDLs for Newport Bay adopted through Santa Ana Water Board Resolution R8-2022-0012; the WQBELs for all other metals and the WQBEL for copper discharges to San Diego Creek remain effective and unchanged by the adoption of the Copper TMDLs.

Permittees must carry out an effective portfolio of projects and programs for the control of metals in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. General
A. For Appendix 7, acute concentration shall mean the average concentration of dissolved metals measured in representative samples taken in a 24-hour period.

B. For Appendix 7, chronic concentration shall mean the average concentration of dissolved metals measured in representative samples taken in a 96-hour period.

II. WQBELs for Cadmium, Dissolved
A. Discharges of runoff from MS4s must not transport more than 9,589 pounds of dissolved cadmium into Upper Newport Bay per year.

B. Discharges of dissolved cadmium in runoff from MS4s to Upper Newport Bay must not exceed:

1. Acute concentrations of 42 micrograms per liter (µg/L).

2. Chronic concentrations of 9.3 µg/L.

C. Discharges of runoff from MS4s to San Diego Creek at Campus Drive must not exceed the concentrations shown in Table 7.1 below under the indicated flow conditions.

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Table 7.1: Summary of Hardness-based WQBELs for Dissolved Cadmium in San Diego Creek
Flow Base
≤20 cfs
Small
21 to 181 cfs
Medium
182 to 815 cfs
Large
>815 cfs
Hardness 400 mg/L 322 mg/L 236 mg/L 197 mg/L
Acute (µg/L) 19.1 15.1 10.8 8.9
Chronic (µg/L) 6.2 5.3 4.2 --
cfs = cubic feet per second
III. WQBELs for Chromium
A. Discharges of runoff from MS4s must not transport more than 5.66 kg/year of chromium into Rhine Channel.

IV. WQBELs for Copper, Dissolved
A. Discharges of runoff from MS4s must not transport more than 3,043 pounds of dissolved copper into Newport Bay per year. This WBQBEL shall be superseded by the WQBELs in Appendix 10 upon the effective date of the Copper TMDLS for Newport Bay adopted through Santa Ana Water Board Resolution R8-2022- 0012.

B. Discharges of dissolved copper in runoff from MS4s to Newport Bay must not exceed:

1. Acute concentrations of 4.8 micrograms per liter (µg/L).

2. Chronic concentrations of 3.1 µg/L.

This WBQBEL shall be superseded by the WQBELs in Appendix 10 upon the effective date of the Copper TMDLS for Newport Bay adopted through Santa Ana Water Board Resolution R8-2022-0012.

C. Discharges of dissolved copper in runoff from MS4s to San Diego Creek at Campus Drive must not exceed the concentrations shown in Table 7.2 below under the indicated flow conditions. This WBQBEL shall not be superseded by the WQBELs in Appendix 10.

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Table 7.2: Summary of Hardness-based Dissolved Copper WQBELs for San Diego Creek
Flow Base
≤20 cfs
Small
21 to 181 cfs
Medium
182 to 815 cfs
Large
>815 cfs
Hardness 400 mg/L 322 mg/L 236 mg/L 197 mg/L
Acute (µg/L) 50 40 30.2 25.5
Chronic (µg/L) 29.3 24.3 18.7 --
cfs = cubic feet per second
V. WQBELs for Lead, Dissolved
A. Discharges of runoff from MS4s must not transport more than 17,638 pounds of dissolved lead into Newport Bay per year.

B. Discharges of dissolved lead in runoff from MS4s to Newport Bay must not exceed:

1. Acute concentrations of 210 micrograms per liter (µg/L).

2. Chronic concentrations of 8.1 µg/L.

C. Discharges of dissolved lead in runoff from MS4s to San Diego Creek at Campus Drive must not exceed the concentrations shown in Table 7.3 below under the indicated flow conditions.

Table 7.3: Summary of Hardness-based Dissolved Lead WQBELs for San Diego Creek
Flow Base
≤20 cfs
Small
21 to 181 cfs
Medium
182 to 815 cfs
Large
>815 cfs
Hardness 400 mg/L 322 mg/L 236 mg/L 197 mg/L
Acute (µg/L) 281 224 162 134
Chronic (µg/L) 10.9 8.8 6.3 --
cfs = cubic feet per second
VI. WQBELs for Mercury

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A. Discharges of runoff from MS4s must not transport more than 0.0171 kg/year of mercury into Rhine Channel.

VII. WQBELs for Zinc, Dissolved
A. Discharges of runoff from MS4s must not transport more than 174,057 pounds of dissolved zinc into Newport Bay per year.

B. Discharges of dissolved zinc in runoff from MS4s to Newport Bay must not exceed:

1. Acute concentrations of 90 micrograms per liter (µg/L).

2. Chronic concentrations of 81 µg/L.

C. Discharges of dissolved zinc in runoff from MS4s to San Diego Creek at Campus Drive must not exceed the concentrations shown in Table 7.4 below under the indicated flow conditions.

Table 7.4: Summary of Hardness-based Dissolved Zinc WQBELs for San Diego Creek
Flow Base
≤20 cfs
Small
21 to 181 cfs
Medium
182 to 815 cfs
Large
>815 cfs
Hardness 400 mg/L 322 mg/L 236 mg/L 197 mg/L
Acute (µg/L) 379 316 243 208
Chronic (µg/L) 382 318 244 --
cfs = cubic feet per second
VIII. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in section VIII of Appendix 7. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

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B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

D. Develop and implement an approved Watershed Management Plan addressing the waterbody-pollutant combination pursuant to section XII of the Order. The schedule for attaining the WQBELs shall be as short as possible.

F. Demonstrate that the receiving waterbody is meeting the numeric targets designated in the USEPA’s TMDL for Toxic Pollutants in San Diego Creek and Newport Bay. For reference, numeric targets are summarized below in Tables

7.5 through 7.7. Actual ambient hardness must be determined for each monitoring sample regardless of which flow condition exists.

Table 7.5: Numeric Targets (µg/L) for Metals Based on Flow Tiers for San Diego Creek
Dissolved Metal
Base flows
(≤20 cfs)
hardness @
400 mg/L
Small flows
(21-191 cfs)
hardness @
322 mg/L
Medium flows
(182-815 cfs)
hardness @
236 mg/L
Large
flows
(>815 cfs)
hardness @
197 mg/L
Acute Chronic Acute Chronic Acute Chronic Acute
Cadmium (µg/L) 19.1 6.2 15.1 5.3 10.8 4.2 8.9
Copper (µg/L) 50 29.3 40 24.3 30.2 18.7 25.5
Lead (µg/L) 281 10.9 224 8.8 162 6.3 134

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Zinc (µg/L) 379 382 318 243 224 208
Table 7.6. Numeric Targets (µg/L) for Metals in Newport Bay Metal Dissolved saltwater
acute target (µg/L)
Dissolved saltwater
chronic target (µg/L)
Alternative target in
saltwater sediments
(mg/kg dry)
Cadmium (Cd) 42 9.3 0.67
Copper (Cu) 4.8 3.1 18.7
Lead (Pb) 210 8.1 30.2
Zinc (Zn) 90 81 124
Table 7.7 Numeric Targets for Chromium and Mercury in Rhine Channel Metal Sediment dry target
(mg/kg dry)
Alternative fish tissue target
(mg/kg wet)
Chromium (Cr) 52 0.2
Mercury (Hg) 0.13 0.3*
*The Mercury tissue target is interpreted as 0.3 mg/kg wet methylmercury (EPA proposed criteria and USFWS 2000).

IX. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 8

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Appendix 8

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR METALS IN

SAN GABRIEL RIVER AND IMPAIRED TRIBUTARIES
The following water quality-based effluent limitations (WQBELs) apply to discharges in runoff from MS4s owned or controlled by Permittees discharging into Coyote Creek, which is located within the jurisdiction of the Los Angeles Water Board. The WQBELs are based on and consistent with the assumptions and requirements of the Metals TMDLs into San Gabriel River and Impaired Tributaries promulgated by the USEPA on March 26, 2007, and the corresponding implementation plan adopted by the Los Angeles Water Board through Resolution R13-004. The implementation plan establishes compliance deadlines of September 30, 2023 for dry weather discharges and September 30, 2026 for wet weather discharges. The compliance deadline for dry weather discharges has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of metals in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. General
A. Runoff samples and flow volumes used to assess compliance with the WQBELs in this Appendix must be taken at the Los Angeles County Department of Public Works (LACDPW) flow gauge station F354-R, located just above the Long Beach Water Reclamation Plant. This location assesses the Permittees’ compliance on a collective basis. The Executive Officer is authorized to use alternative locations and methods to assess compliance of the Permittees as part of the PMRP developed and approved according to Monitoring and Reporting Program R8-2024-0001.

B. Wet weather WQBELs apply when the maximum daily flow in the creek is equal to or greater than 156 cubic feet per second (cfs), as measured at station F-354- R.

C. The percentage area of the developed portion of the Coyote Creek watershed covered by MS4 Permittees was calculated to be 91.5%.

II. WQBELs for Copper
A. By September 30, 2023, dry weather discharges of runoff from MS4s into Coyote Creek must not transport more than 0.941 kilogram per day (kg/d) of total recoverable copper.

B. By September 30, 2026, total recoverable copper in discharges of runoff from MS4s during wet weather into Coyote Creek must not exceed a maximum daily mass load calculated using the following formula:

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Daily storm volume x 24.71 = maximum daily wet weather mass load for total recoverable copper (kg/d)
III. WQBELs for Lead
A. By September 30, 2026, total recoverable lead in discharges of runoff from MS4s during wet weather into Coyote Creek must not exceed a mass calculated using the following formula:

Daily storm volume x 96.99 = maximum daily wet weather mass load for total recoverable lead (kg/d)
IV. WQBELs for Zinc
A. By September 30, 2026, total recoverable zinc in discharges of runoff from MS4s during wet weather into Coyote Creek must not exceed a mass calculated using the following formula:

Daily storm volume x 144.57 = maximum daily wet weather mass load for total recoverable zinc (kg/d)
V. Alternative Concentration-Based WQBELs
A. In lieu of compliance with the mass-based WQBELs for wet weather in sections II to IV of Appendix 2 above, Permittees may demonstrate compliance with the wet weather concentration-based WQBELs identified in Table 8.1 below, by September 30, 2026:

Table 8.1: Summary of Wet Weather Concentration-Based Effluent Limitations Copper,
total recoverable
Lead,
total recoverable
Zinc,
total recoverable
Wet Weather2

24.71 µg/L 96.99 µg/L 144.57 µg/L
2 As measured at LACDPW Station F-354-R.

VI. Alternative Interim WQBELs for Dry and Wet Weather Discharges In lieu of compliance with the mass-based or alternative concentration-based WQBELs above, Permittees may demonstrate compliance with the following:

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A. Permittees shall immediately attain a 70% reduction in the difference between the last copper loading value calculated prior to 2013 and the dry-weather WQBEL of 0.951 kg/day.

B. Permittees shall immediately achieve a 35% reduction in the difference between the last copper, lead, and zinc loading values calculated prior to 2013 and their respective wet weather WQBELs in sections II, III, and IV above of this Appendix

8. C. By September 30, 2023, Permittees shall attain a 65% reduction in the difference between the last copper, lead, and zinc loading values calculated prior to 2013 and their respective wet weather WQBELs in sections II, III, and IV above of this Appendix 8.

VII. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order R8-2024- 0001 (Order) and as shown in this section VII of Appendix 8. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

D. For wet weather compliance only, demonstrate that there are no exceedances of the Alternative Concentration-Based WQBELs specified in section V of Appendix 8 in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

E. Demonstrate attainment of the Alternative Interim WQBELs specified in section VI of Appendix 8.

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F. Where the final compliance deadline for achievement of the WQBEL has not passed, develop and implement an approved Watershed Management Plan addressing the waterbody-pollutant combination pursuant to section XII of the Order.

G. Demonstrate that all non-stormwater and all stormwater runoff up to and including the volume equivalent to the 85th percentile, 24-hour storm event is retained for the drainage area tributary to the applicable receiving waters. The runoff retention must occur according to an approved Watershed Management Plan under section XII of the Order and include ongoing monitoring and adaptive management requirements.

H. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan.

VIII. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 9

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Appendix 9

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR SELENIUM IN

FRESHWATER, NEWPORT BAY WATERSHED
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into the Newport Bay watershed as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Selenium TMDL for freshwater in the Newport Bay watershed. The compliance deadline of June 20, 2049 specified in the Basin Plan has not passed.

Permittees must carry out an effective portfolio of projects and programs for the control of metals in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Selenium
A. By June 20, 2049, discharges of selenium in runoff from MS4s to Newport Bay at Costa Mesa Channel must not exceed concentrations of 5 µg Se/L in the water column.

1. This WQBEL is derived from the CTR and expressed as an arithmetic mean that is calculated semi-annually. The first semi-annual period used to calculate the arithmetic mean is April 1 through September 30. The second semi-annual period is October 1 through March 31.

2. This WQBEL applies to dry-weather conditions and wet-weather runoff produced by up to but excluding 0.1 inches of rain. Rainfall is measured at the Tustin-Irvine Ranch Rain Gauge Station. Demonstrations of attainment of the WQBEL must represent these same conditions.

B. By June 20, 2049, discharges of selenium in runoff from MS4s to the San Diego Creek must not exceed concentrations of 10 µg Se/L in the water column.

1. This WQBEL is based on probable water column concentrations that are expected to achieve tissue-based numeric TMDL targets and are derived from the biodynamic model, as detailed in the Linkage Analysis of the Selenium TMDL.

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C. By June 20, 2049, discharges of selenium in runoff from MS4s to the Santa Ana-Delhi Channel must not exceed concentrations of 11 µg Se/L in the water column.

2. This WQBEL applies to dry weather conditions and wet weather runoff produced by up to but excluding 0.1 inches of rain. Rainfall is measured at the Tustin-Irvine Ranch Rain Gauge Station. Demonstrations of attainment of the WQBEL must represent these same conditions.

D. By June 20, 2049, discharges of selenium in runoff from MS4s to the Big Canyon Wash must not exceed concentrations of 1 µg Se/L in the water column.

II. Requirements for Offset and Trading Program
Permittees may elect to carry out an effective Offset and Trading Program designed to eliminate excess selenium loads from point and non-point sources (primarily rising groundwater). The Offset and Trading Program must be managed to ensure that the net effect on water quality and beneficial uses of continued point source discharges of selenium mitigated by offsets is better than would be expected if the regulated discharge were prohibited altogether.

A. Permittees must meet one of the following eligibility requirements to participate in the Offset and Trading Program by demonstrating that:

1. There are no reasonably feasible or practicable treatment technologies available that can achieve compliance with the applicable water quality objective for selenium (i.e., concentrations of 5 µg Se/L in the water column) at the point of discharge.

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2. It is not feasible or practicable to eliminate the discharge because it would pose unreasonable risk to human health, public safety, the natural environment, or cause economic hardship on the surrounding community.

3. The discharge is not expected to unreasonably or adversely affect the beneficial uses of the receiving water downstream after the excess selenium load from the discharge is offset by reductions in the selenium load from other discharges.

B. The excess selenium load from a discharge shall mean the mass of selenium in the discharge that exceeds the mass of selenium in a discharge of the same volume and duration where the concentration is equal to the CTR-based WQBEL.

C. The activities occurring under the Offset and Trading Program must offset the Permittees’ estimated discharges of excess selenium plus an amount that accounts for uncertainty in the estimate. To account for uncertainty, a factor of safety of 2 must be used to calculate the amount of excess selenium that must be offset for a given discharge.

D. Estimates of the selenium load from a discharge must be based on empirical measurements of concentrations, flow, and duration at representative points of discharge.

E. The estimate of the selenium removed from discharges to the receiving waters must be based on empirical measurements of concentration, flow, and duration of the treated flow and subsequent discharge to the receiving waters, if any.

Estimates must be based on measured quantities of selenium removed, not speculative or theoretical quantities.

F. The excess selenium load from a discharge to San Diego Creek, Santa AnaDelhi Channel, and Big Canyon Wash must be offset by activities to reduce selenium loads in the same watershed. The Permittee must not offset discharges of selenium using load reductions that they are already responsible for.

G. If Permittees elect to carry out an effective Offset and Trading Program, they must prepare and submit a plan to implement the Offset and Trading Program according to the requirements of this Appendix and the Offset and Trading Program requirements of the Santa Ana Region’s Basin Plan, starting on page 6-95 as of the date of issuance of this Order.

H. The Offset and Trading Program plan must be approved by the Executive Officer following a 30-day public review period to be used for compliance. Except for inconsequential grammatical corrections, changes to the plan are subject to the approval of the Executive Officer. Responsible Permittees must implement the plan upon approval by the Executive Officer.

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I. Where the Offset and Trading Program is not implemented consistent with the terms and conditions specified by the Executive Officer, Permittees may not rely on the Offset and Trading Program as a method to demonstrate compliance with the WQBELs in section I of Appendix 9. Notwithstanding any other enforcement option available, the Santa Ana Water Board may also elect to terminate eligibility to participate in the Offset and Trading Program, require a higher offset ratio from the non-compliant Permittee, or impose additional terms and conditions to ensure full compliance by the non-compliant Permittee.

III. Requirements for BMP Strategic Plans
The following requirements apply where Permittees have chosen to develop a BMP Strategic Plan.

A. The BMP Strategic Plan must document the Permittees’ projects and programs that are designed to attain the CTR-based water column WQBEL. The BMP Strategic Plan must include the following:

1. A description of the roles and responsibilities of the parties that will implement the BMP Strategic Plan;

2. A description of the source control activities and their levels of effort that prevent or minimize new or existing discharges of selenium;

3. A description of projects that result in reductions of selenium in discharges, including their characteristics, level of effort, and the expected quantities of selenium removed during the planning period;

4. A program to evaluate and report on the technical, social, and economic feasibility of deploying available and emerging technology to control the discharge of selenium a minimum of once every five years;

5. A schedule for the completion of projects or the accomplishment of measurable goals; and

6. A planning period over which the above projects and programs will be carried out.

B. The BMP Strategic Plan must also contain all the required elements outlined in the Santa Ana Region’s Basin Plan, starting on page 6-91 as of the date of issuance of this Order.

C. Responsible Permittees must evaluate and report on the effectiveness of their projects and programs under the BMP Strategic Plan according to the requirements of Monitoring and Reporting Program R8-2024-0001.

D. The BMP Strategic Plan must be reviewed and approved by the Executive Officer, subject to a 30-day public review period.

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1. Responsible Permittees must fully implement a BMP Strategic Plan upon approval.

2. Except for inconsequential technical or grammatical changes, amendments to a BMP Strategic Plan are subject to the review and approval of the Executive Officer, subject to a 30-day public review period.

E. Where the BMP Strategic Plan is not implemented consistent with the approved plan and schedule, Permittees may not rely on the BMP Strategic Plan as a method to demonstrate compliance with the WQBELs in section I of Appendix

9. IV. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section IV of Order No. R8-2024- 0001 (Order) and as shown in this section IV of Appendix 9. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP. This showing may be made in the receiving waters and/or in the effluent at the discharge point at MS4 outfalls.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

D. Demonstrate that the Permittee’s MS4 discharge to the receiving waters is offset by reductions in selenium pursuant to an approved Offset and Trading Program that meets the requirements of section II of Appendix 9.

E. Implement an approved BMP Strategic Plan, consistent with the approved plan and schedule, according to section III of Appendix 9.

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F. Demonstrate that all non-stormwater and all stormwater runoff up to and including the volume equivalent to the 85th percentile, 24-hour storm event is retained for the drainage area tributary to the applicable receiving waters. The runoff retention must occur according to an approved Watershed Management Plan under section XII of the Order and include ongoing monitoring and adaptive management.

G. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan.

IV. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 10

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Appendix 10

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR COPPER IN UPPER AND

LOWER NEWPORT BAY
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into Newport Bay as indicated in Appendix 1. The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the TMDLs for Copper in Upper and Lower Newport Bay adopted through Santa Ana Water Board Resolution R8-2022-0012. The WQBELS in this Appendix will not be effective unless and until the Copper TMDLs are approved by USEPA. The compliance deadline is 12 years after the date of USEPA approval of the Copper TMDLs.

Upon the effective date of the Copper TMDLs, Permittees must carry out an effective portfolio of projects and programs for the control of copper in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below as soon as possible, but no later than 12 years after USEPA approval of the Copper TMDLs.

I. WQBELs for Copper, Dissolved
A. Discharges of runoff from MS4s must not transport more than 2,501 pounds of dissolved copper into Newport Bay per year.

B. Discharges of dissolved copper in runoff from MS4s to Newport Bay must not exceed:
i. Acute concentrations of 4.8 micrograms per liter (µg/L). ii. Chronic concentrations of 3.1 µg/L.

II. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in this section II of Appendix 10. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

C. Demonstrate that the discharge from the Permittee’s MS4 did not cause or contribute to an exceedance of the WQBEL, because the exceedance is the

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result of an authorized or exempt non-stormwater discharge specified in section IV.A.2 of the Order during a specific sampling event. The water quality characteristics must be based on the source specific water quality monitoring data from the authorized or conditionally exempt essential non-stormwater discharge or other relevant information documenting the characteristics of the specific non-stormwater discharge.

F. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan.

III. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 11

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Appendix 11

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR BACTERIAL INDICATOR

TMDL IN THE MIDDLE SANTA ANA RIVER WATERSHED
The following water quality-based effluent limitations (WQBELs) apply to discharges in runoff from MS4s owned or controlled by Permittees discharging into the Middle Santa Ana River (MSAR) Watershed as indicated in Appendix 1, which includes the cities of Clairmont and Pomona (covered under a separate NPDES Permit). The WQBELs in this Appendix are based on and consistent with the assumptions and requirements of the Bacterial Indicator TMDLs for MSAR Watershed. The compliance deadline for dry weather conditions specified in the Basin Plan passed on December 31, 2015, while the compliance deadline for wet weather conditions has not passed and is December 31, 2025.

Permittees must carry out an effective portfolio of projects and programs for the control of bacteria in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Escherichia coli
A. During wet weather conditions (November 1 through March 31), MS4 Permittees’ projects and programs must achieve the following effluent limitation as soon as possible, but not later than December 31, 2025.

1. The 5-sample, 30-day logarithmic mean of Escherichia coli in the receiving waters is less than 113 organisms/100 mL and not more than 10% of the samples exceed 212 organisms/100 mL for any 30-day period.

B. During dry weather conditions (April 1 through October 31), MS4 Permittees’ projects and programs must achieve the following effluent limitation:

C. The above WQBELs for Escherichia coli are temporarily suspended when high flow conditions preclude safe recreation in or near freshwater stream channels that have been engineered, heavily modified or maintained to serve as flood control facilities. Specifically, WQBELs are suspended when: 1) stream velocity is greater than 8 feet per second; or 2) the product of stream depth and velocity is greater than 10 square feet per second. If representative stream gauge data are not available; 3) the WQBELs are suspended when rainfall in the tributary area is greater than or equal to 0.5 inches in 24 hours. The suspension ends 24- hours after the event, unless measured stream flow falls within normal pre-storm conditions (i.e., flow velocity is less than the 98th percentile, as calculated from a calibrated hydrograph).

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II. Comprehensive Bacterial Reduction Plan
The Permittees must have an implementation plan for projects and programs for the control of bacteria that complies with the requirements of this section and that has been approved by the Executive Officer. The Permittees must:

A. Revise or amend the Comprehensive Bacterial Reduction Plan (CBRP) to comply with the requirements of section I above. The initial draft CBRP or amendment must be submitted to the Executive Officer for approval within two years of the effective date of this Order, or as prescribed by the Executive Officer. The Executive Officer is authorized to approve the draft or amendments as submitted, require additional information, or approve them subject to conditions.

1. Permittees must implement the revised or amended CBRP upon approval.

Except for inconsequential grammatical or technical corrections, subsequent updates or amendments to CBRP are subject to the review and approval of the Executive Officer. Updates or amendments must be submitted for approval not less than 30 days prior to implementation of the proposed changes.

2. The revised or amended CBRP must include those best management practices that are or will be implemented within the Permittees’ jurisdiction for the control of bacteria, the levels of effort for their implementation, the methods for determining compliance with the WQBELs, and the method(s) for evaluating the effectiveness of those practices.

Because the compliance deadline for the Bacterial Indicator TMDLs for the MSAR Watershed specified in the Basin Plan has passed, the CBRP does not automatically serve as an alternative means of compliance with the WQBELs; however, it serves as an important roadmap for how the Permittees plan to comply with the WQBELs.

B. Participate in watershed-wide projects and programs where the Permittee deems that there is a mutual interest or benefit to achieving the WQBELs in section I.A above.

C. Develop and apply objective performance metrics to track and assess the effectiveness of individual best management practices or systems of best management practices described in the Permittees’ CBRP. The Permittees must include the WQBELs as part of these performance metrics.

E. Any updated or new CBRPs are subject to the approval of the Executive Officer.

The Executive Officer will provide a minimum of 30 days for public review prior to approving the updated or new CBRPs.

F. Except for grammatical or inconsequential technical corrections, subsequent updates or amendments to CBRPs are subject to the review and approval of the

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Executive Officer. Subsequent updates or amendments to CBRPs must be submitted to the Executive Officer for approval not less than 30 days prior to implementation of the proposed changes.

III. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in this section III of this Appendix 11. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

D. Where the final compliance deadline for achievement of the WQBEL has not passed, develop and implement an approved Watershed Management Plan addressing the waterbody-pollutant combination pursuant to section XII of the Order. The Watershed Management Plan is only available to demonstrate compliance with the WQBEL for wet weather conditions, as the compliance deadline for dry weather conditions has passed. The CBRP may function as a wet weather conditions WMP if it meets the requirements of section XII of the Order; the CBRP cannot serve as an alternative means of compliance with the WQBEL for dry weather conditions.

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F. Demonstrate that an alternative indicator (e.g., enterococci) in the Permittee’s MS4 discharge is below levels that are equivalent to a risk to human health less than 32 illnesses/1000 people.

G. Demonstrate, through an approved epidemiological study or quantitative microbial risk assessment (QMRA), that the risk to human health is less than 32 illnesses/1000 people.

IV. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 12

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Appendix 12

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR NUTRIENT TMDL IN

LAKE ELSINORE AND CANYON LAKE
The following water quality-based effluent limitations (WQBELs) apply to discharges in runoff from MS4s owned or controlled by Permittees discharging into Canyon Lake and Lake Elsinore as indicated in Appendix 1. These WQBELs are based on and consistent with the assumptions and requirements of the Lake Elsinore and Canyon Lake Nutrient TMDLs. The compliance deadline of December 31, 2020 specified in the Basin Plan has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of nutrients in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Canyon Lake
A. Discharges of runoff from MS4s must not transport more than 306 kg of total Phosphorus and 3,974 kg of total Nitrogen into Canyon Lake per year.

B. The nutrient loads shall be calculated using a running average of ten (10) consecutive estimates of annual loads.

C. Any nutrient loads that exceed the WQBELs in Table 12.1 below must be offset by reductions in nutrient loads from in-lake sediment.

Table 12.1: Summary of Nutrient WQBELs for Runoff from MS4s into Canyon Lake WQBEL Total Phosphorus (kg/yr) Total Nitrogen (kg/yr)
Runoff from MS4s 306 3,974
II. WQBELs for Lake Elsinore
A. Discharges of runoff in MS4s from sources downstream of Canyon Lake must not transport more than 124 kg of total Phosphorus and 349 kg of total Nitrogen into Lake Elsinore per year to the maximum extent practicable.

B. The nutrient loads shall be calculated using a running average of ten (10) consecutive estimates of annual loads.

C. Any nutrient loads that exceed the WQBELs in Table 12.2 below must be offset by reductions in nutrient loads from in-lake sediment or other sources.

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Table 12.2: Summary of Nutrient WQBELs for Runoff from MS4s into Lake Elsinore WQBEL Total Phosphorus (kg/yr)
Ten year running average
Total Nitrogen (kg/yr)
Ten year running average
Runoff from MS4s 124 349
III. Comprehensive Nutrient Reduction Plan
The Permittees must have an implementation plan for projects and programs for the control of nutrients that complies with the requirements of this Order and that has been approved by the Executive Officer. The Permittees must:

A. Revise or amend their Comprehensive Nutrient Reduction Plan (CNRP) to comply with the requirements of this Order. The initial draft CNRP or amendment must be submitted to the Executive Officer for approval within two years of the effective date of this Order, or as prescribed by the Executive Officer. The Executive Officer is authorized to approve the draft or amendments as submitted, require additional information, or approve them subject to conditions.

1. Permittees must implement the revised or amended CNRP upon approval.

Except for inconsequential grammatical or technical corrections, subsequent updates or amendments to the CNRP are subject to the review and approval of the Executive Officer and submitted for approval not less than 30 days prior to implementation of the proposed changes.

2. The revised or amended CNRP must include those best management practices that are or will be implemented within their jurisdiction for the control of nutrients, the levels of effort for their implementation, the methods for demonstrating compliance with the WQBELs, and the method(s) for evaluating the effectiveness of those practices according to the requirements of Order No. R8-2024-0001.

B. Participate in watershed-wide projects and programs where the Permittee deems that there is a mutual interest or benefit to achieving nutrient waste load allocations.

C. Because the compliance deadline for the Lake Elsinore and Canyon Lake Nutrient TMDLs specified in the Basin Plan has passed, the CNRP does not serve as an alternative means of compliance with the WQBELs; however, it serves as an important roadmap for how the Permittees plan to comply with the WQBELs.

IV. Reduction of In-lake Sediment Nutrient Loads
The WQBELs in Tables 12.1 and 12.2 presume that nutrient loads of phosphorous from sediment in Lake Elsinore are reduced by 16% under moderate and dry conditions, as described in the Staff Report for the TMDLs. Responsible Permittees

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must contribute to activities that result in a 16% reduction in phosphorous loads from the sediment to the water column of Lake Elsinore. The baseline for evaluating the reduction must be the sediment load measured in 2004. The methods used for compliance must be documented in the CNRP or the PMRP.

V. Requirements for Offset and Trading Program
Permittees may elect to carry out an effective Offset and Trading Program designed to eliminate excess nitrogen and phosphorus loads from point and non-point sources. The Offset and Trading Program must be managed to ensure that the net effect on water quality and beneficial uses of continued point source discharges of nitrogen and phosphorus mitigated by offsets is better than would be expected if the regulated discharge were prohibited altogether. The Offset and Trading Program must be approved by the Executive Officer.

A. The excess nitrogen and phosphorus loads from a discharge shall mean the mass of nitrogen and phosphorus in the discharge that exceeds the mass of nitrogen and phosphorus in a discharge of the same volume and duration where the concentration is equal to the applicable WQBELs.

B. The activities occurring under the Offset and Trading program must offset the Permittee’s estimated discharges of excess nitrogen and phosphorus plus an amount that accounts for uncertainty in the estimate.

C. Estimates of the nitrogen and phosphorus loads from a discharge must be based on empirical measurements of concentrations, flow, and duration at representative points of discharge.

D. The estimate of the nitrogen and phosphorus removed from discharges to the receiving waters must be based on empirical measurements of concentration, flow, and duration of the treated flow and subsequent discharge to the receiving waters, if any. Estimates must be based on measured quantities of nitrogen and phosphorus removed, not speculative or theoretical quantities.

E. There are currently two Offset and Trading Programs in place. For Lake Elsinore, the Lake Elsinore Aeration and Mixing System (LEAMS) was installed and is operating to reduce the internal loading of phosphorus and nitrogen from sediment in Lake Elsinore. For Canyon Lake, a semi-annual, large-scale aluminum sulfate (“alum”) application is used to offset excess phosphorus.

However, these two Offset and Trading Programs have not been formally documented in plans approved by the Executive Officer. Accordingly, within two years from the effective date of this Order, plans for these Offset and Trading Programs or an alternative must be submitted for review and approval by the Executive Officer.

F. All Offset and Trading Program plans are subject to a 30-day written public comment period before approval by the Executive Officer. Except for

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inconsequential grammatical corrections, changes to the plans are subject to the approval of the Executive Officer. Responsible Permittees must implement the plans upon approval by the Executive Officer.

G. Where the Offset and Trading Program is not implemented consistent with the terms and conditions specified by the Executive Officer, Permittees may not rely on the Offset and Trading Program as a method to demonstrate compliance with the WQBELs in sections I and II of Appendix 12.

Notwithstanding any other enforcement option available, the Santa Ana Water Board may also elect to terminate eligibility to participate in the Offset and Trading Program or require a higher offset ratio from the non-compliant Permittee.

VI. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in section VI of this Appendix 12. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

D. Demonstrate that the Permittee’s MS4 discharge to the receiving waters is offset by reductions in nitrogen and phosphorus pursuant to an approved Offset and Trading Program that meets the requirements of section V of Appendix 12.

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F. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) designated in the TMDL, as specified in the Basin Plan. For reference, Total TMDL Allocations are summarized in Table 12.3 and are specified as 10-year running averages.

Table 12.3: Total TMDL Allocations for Lake Elsinore and Canyon Lake Total Phosphorous
(kg/yr)
Total Nitrogen (kg/yr)
Lake Elsinore 28,584 239,025
Canyon Lake 8,691 37,735
VII. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Appendix 13

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Appendix 13

WATER QUALITY-BASED EFFLUENT LIMITATIONS FOR NUTRIENT TMDL FOR

DRY HYDROLOGICAL CONDITIONS IN BIG BEAR LAKE
The following water quality-based effluent limitations (WQBELs) apply to discharges of runoff from MS4s owned or controlled by Permittees discharging into Big Bear Lake as indicated in Appendix 1. These WQBELs are based on and consistent with the assumptions and requirements of the Nutrient TMDL for Dry Hydrological Conditions in Big Bear Lake. The deadline of December 31, 2015 specified in the Basin Plan has passed.

Permittees must carry out an effective portfolio of projects and programs for the control of nutrients in stormwater and authorized non-stormwater runoff from their MS4s that attain the WQBELs below.

I. WQBELs for Phosphorus, Total
A. The annual average discharge of total phosphorous from MS4s into Big Bear Lake during dry hydrological conditions must not exceed 475 pounds.

1. Dry hydrological conditions shall mean a period of time where the average annual inflow from tributaries to Big Bear Lake ranges from 0 to 3,049 acrefeet, average lake levels range from 6,671 to 6,735 feet and annual precipitation range from 0 to 23 inches.

2. Tributary inflow must be measured when collecting water quality samples to calculate total phosphorus loads.

3. The Permittees must determine the rate of influx of sediment and phosphorus loads to Big Bear Lake at the mouths of Rathbun, Summit, Knickerbocker Creeks, and from other outfalls within the jurisdiction of the Permittees.

II. Compliance Determination
Permittees responsible for complying with the WQBELs must demonstrate compliance through any of the means identified in section VII of Order No. R8- 2024-0001 (Order) and as shown in section II of this Appendix 13. Processes used to analyze data and support demonstrations of compliance, as well as compliance monitoring locations, must be approved by the Executive Officer as part of the PMRP.

A. Demonstrate that there are no exceedances of the WQBEL in the Permittee’s MS4 discharge at the compliance point(s) identified in the PMRP.

B. Demonstrate that there is no discharge from the Permittee’s MS4(s) during the relevant time period.

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C. Demonstrate that the discharge from the Permittee’s MS4 did not cause or contribute to an exceedance of the WQBEL, because the exceedance is the result of an authorized or exempt non-stormwater discharge specified in section IV.A.2 of the Order during a specific sampling event. The water quality characteristics must be based on the source specific water quality monitoring data from the authorized or conditionally exempt essential non-stormwater discharge or other relevant information documenting the characteristics of the specific non-stormwater discharge.

E. Demonstrate that the receiving waterbody is meeting the combined Waste Load Allocations and Load Allocations (Total TMDL Allocations) during dry weather conditions designated in the TMDL, as specified in the Basin Plan and summarized below:

1. The Total Phosphorus concentration is no greater than 35 ug/L; a. To determine the annual average for the Total Phosphorus concentration, nutrient data from both the photic composite and discrete bottom samples must be averaged by station number and month; a calendar year average is obtained for each sampling location by averaging the average of each month; and finally, the separate annual averages for each location are averaged to determine the lake-wide average. The open-water sampling locations used to determine the annual average are MWDL1, MWDL2, MWDL6, and MWDL9 (see
Basin Plan, 1.B.4. Implementation, Task 4.2, Table 6-1a-i).

2. Macrophyte coverage is 30-40% on a total lake area basis, calculated as a 5- year running average based on measurements taken at peak macrophyte growth as determined in the Aquatic Plant Management Plan (Basin Plan

1.B.4, Implementation, Task 6C);

3. 95% eradication of Eurasian Watermilfoil and any other invasive aquatic vascular plant species, on a total area basis; and

4. The growing season (May 1 through October 31 each year) average for Chlorophyll a concentration is no greater than 14 ug/L.

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a. For Chlorophyll a, the open-water sampling locations used to determine the growing season average are MWDL1, MWDL2, MWDL6 and
MWDL9 (see 1.B.4. Implementation, Task 4.2, Table 6-1a-i). The Chlorophyll a data from the photic samples is averaged by station number and month; a growing season average is obtained for each sampling location by averaging the average of each month; and finally, the separate growing season averages for each location are averaged to determine the lake-wide average.

III. Monitoring and Reporting
Monitoring and reporting requirements shall be as outlined in the Monitoring and Reporting Program (MRP) in Attachment C of this Order.

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Attachment A
Glossary

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Attachment A

GLOSSARY
This Glossary has been prepared for the convenience of the reader. This Glossary is not an exhaustive catalog of terminology used in this Order. Additional terminology is defined in the Clean Water Act, USEPA regulations, and the California Water Code; all such terms not appearing below are incorporated into this Permit by reference.

Annual Progress Report – A report summarizing information required to be submitted annually to the Santa Ana Water Board on or before November 15th.

Authorized Non-Stormwater Discharges – Non-stormwater discharges authorized pursuant to an NPDES permit.

Basin Plan – The Water Quality Control Plan for the Santa Ana River Basin, as amended or revised.

Beneficial Uses – The uses of water necessary for the survival or well-being of man, plants, and wildlife. These uses of water serve to promote tangible and intangible economic, social, and environmental goals. “Beneficial Uses” that may be protected include, but are not limited to, domestic, municipal, agricultural, and industrial supply; power generation; recreation; aesthetic enjoyment; navigation; and preservation and enhancement of fish, wildlife, and other aquatic resources or preserves. Existing beneficial uses are uses that were attained in the surface or groundwater on or after November 28, 1975; and potential beneficial uses are those that would probably develop in future years through the implementation of various control measures. “Beneficial Uses” are equivalent to “Designated Uses” under federal law. Water Code section 13050(f) Beneficial Uses for the receiving waters are identified in the Basin Plan.

Best Management Practices (BMPs) – Also known as stormwater control measures and defined in 40 CFR section 122.2. BMPs mean schedules of activities, prohibitions of practices, maintenance procedures, policies and other management practices that are effective to prevent or reduce the pollution of waters of the United States. BMPs also include treatment requirements, operating procedures and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage (40 CFR § 122.2).

Bioassessment – The use of biological community information to evaluate the biological integrity of a waterbody and its watershed. With respect to aquatic ecosystems, bioassessment is the collection and analysis of samples of the benthic macroinvertebrate community together with physical/habitat quality measurements associated with the sampling site and the watershed to evaluate the biological condition (i.e., biological integrity) of a waterbody.

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Biological Integrity – A balanced, integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of natural habitat of the region. Also referred to as ecosystem health. (Karr J.R. and D.R. Dudley. 1981. Ecological perspective on water quality goals. Environmental Management 5:55-

68.)
Biotreatment Control Measure – A subcategory of treatment control measures that employ biological uptake, transformation, or degradation of pollutants as their principal mechanism(s) of pollutant removal. Although a significant portion of the design capture volume or flow will incidentally infiltrate, evaporate, or evapotranspire where conditions allow, the principal of operation involves the discharge of the treated stormwater after detention in a vegetated basin or after passing through porous, biologically active medium, vegetation, or both.

California Toxics Rule (CTR) – Numeric water quality criteria for certain priority toxic pollutants and other water quality standards provisions promulgated by the USEPA for waters in the State of California. The California Toxics Rule is found in 40 CFR part 131.

Commercial Site – Any site that is used for the sale of retail items, food or beverages to the general public, for the sale of wholesale items, and for the sale or dispensing of services, including professional, trade, contracting, banking, property management and other services. Section XIII.D.1 b of Order No. R8-2024-0001 provides a non-exhaustive list of commercial sites. Commercial sites include mobile businesses, including but not limited to those that perform mobile carpet, drape, or furniture cleaning and mobile automobile or other vehicle washing.

Construction Site – Any site where building or grading permits are applicable, the project duration is anticipated to exceed two weeks, and where activities at the site include the following: (1) soil movement; (2) uncovered storage of materials or wastes, such as construction materials, dirt, sand, fertilizer, or landscaping materials; or exterior mixing of cementitious products (i.e., concrete, mortar, or stucco). Construction sites include but are not limited to those with projects requiring coverage under the Construction General Permit.

Contamination – An impairment of the quality of waters of the State by waste to a degree which creates a hazard to the public health through poisoning or through the spread of disease. Contamination includes any equivalent effect resulting from the disposal of waste, whether waters of the State (inclusive of waters of the U.S.) are affected or not. (Wat. Code, §13050(k))
Criteria – Elements of water quality standards, expressed as constituent concentrations, levels, or narrative statements, representing a quality of water that supports a particular use. When criteria are met, water quality will generally protect the designated use. (40 CFR §131.3) “Criteria” are equivalent to “water quality objectives” under state law. (See Wat. Code, §13050(h))

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Critical Milestones – An action or event marking a significant stage in the process of Watershed Management Plan (WMP) development and implementation. A critical milestone is chosen by a Permittee or designated by the Executive Officer and is subject to enforcement if the milestone is not met. Non-critical milestones are not subject to enforcement but must be reported. The distinction between types of milestones is intended to facilitate transparent and more detailed disclosure of the progress of WMP development and implementation and allow early detection of deviations in a schedule that could lead to violations.

DAMP (Drainage Area Management Plan) – A programmatic document developed by the Permittees and approved by the Executive Officer that outlines the major programs and policies that the Permittees individually and/or collectively implement to manage runoff in the Permit Area.

Debris – The remains of anything destroyed or broken or accumulated loose fragments of rock.

Design Capture Flow – (See Permit, section VIII.D.3)
The calculated flow rate of stormwater runoff, typically expressed as cubic feet per second (cfs), must be treated in one or more treatment control measures according to the requirements of this Order.

Design Capture Volume – (See Permit, section VIII.D.2)
The calculated volume of stormwater runoff, typically expressed in gallons or cubic feet, that must be treated in one or more treatment control measures according to the requirements of this Order.

Development Projects – New development or redevelopment with land disturbing activities; structural development, including construction or installation of a building or structure, the creation of impervious surfaces, public agency projects, and land subdivision.

Discretionary Project – A project which requires the exercise of judgment or deliberation when the public agency or body decides to approve or disapprove a particular activity, as distinguished from situations where the public agency or body merely determines whether there has been conformity with applicable statutes, ordinances, or regulations (Cal. Code Regs., tit. 14, § 15357).

Effluent Limit/Limitations – Any restriction on quantities, discharge rates, and concentrations of pollutants which are discharged from point sources into waters of the United States, waters of the “contiguous zone,” or the ocean (40 CFR § 122.2).

Emergency – A sudden, unexpected occurrence, including but not limited to fires or other events, involving a clear and imminent danger, demanding immediate action to prevent or mitigate loss of, or damage to, life, health, property, or essential public services.

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Environmentally Sensitive Areas (ESAs) – An area in which plant or animal life or their habitats are either rare or especially valuable because of their special nature or role in an ecosystem and which would be easily disturbed or degraded by human activities and developments (Pub. Res. Code, § 30107.5). These areas include, but are not limited to:
waterbodies designated with the RARE beneficial use in the Basin Plan (Water Quality Control Plan for the Santa Ana River Basin [1995] and amendments); an area designated in the Ocean Plan as an Area of Special Biological Significance; Marine Protected Areas designated as such pursuant to the Marine Life Protection Act; a waterbody listed as being impaired pursuant to CWA section 303(d); areas designated as preserves or their equivalent under the Natural Communities Conservation Program (Multiple Species Habitat Conservation Plan, MSHCP) within the Cities and Counties of Orange, Riverside and San Bernardino; or any area designated as such by a public agency with designation powers.

Equivalent Alternate Land Uses – An MS4 permittee with regulatory authority over priority land uses may issue a request to the applicable permitting authority that the MS4 permittee be allowed to substitute one or more land uses identified above with alternates land use within the MS4 permittee’s jurisdiction that generates rates of trash that are equivalent to or greater than the priority land use(s) being substituted subject to approval by the Executive Officer. The land use area requested to substitute for a priority land use need not be an acre-for-acre substitution but may involve one or more priority land uses, or a fraction of a priority land use, or both, provided the total trash generated in the equivalent alternative land use is equivalent to or greater than the total trash generated from the priority land use(s) for which substitution is requested. Comparative trash generation rates shall be established through the reporting of quantification measures such as street sweeping and catch basin cleanup records; mapping; visual trash presence surveys, such as the “Keep America Beautiful Visible Litter Survey”; or other information as required by the permitting authority.

Erosion – The process whereby material (such as sediment) is detached and entrained in water or air and can be transported to a different location. Chemical erosion involves materials that are dissolved and removed and transported.

Executive Officer – The Executive Officer of the Santa Ana Regional Water Quality Control Board.

Fixed Facility – A stationary facility that is owned or controlled by a Permittee. A fixed facility includes, but is not limited to, corporate yards, public parks, cemeteries, or airfields, libraries, fire and police stations, and public power generation, sewer, or water utilities. section XIV.B.1 of Order No. R8-2024-0001 provides a non-exhaustive list of fixed facilities.

Full Capture System – A treatment control, or series of treatment control measures, that traps all particles that are 5 mm or greater, and has a design treatment capacity that is either:

1. Not less than the peak flow rate resulting from a one-year, one-hour, storm in the

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drainage area, or

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

Prior to installation, full capture systems must be certified by the Executive Director, or designee of the State Water Board. Uncertified full capture systems will not satisfy the requirements of the Trash Amendments to the Ocean Plan and the ISWEBE Plan.

Full Capture System Equivalency – The trash load that would be reduced if full capture systems were installed, operated, and maintained for all storm drains that capture runoff from priority land use areas. 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 permitting authority.

General Utility Vaults Permit – State Water Board Order No. 2014-0174-DWQ, NPDES No. CAG990002.

Geometric Mean – The antilog of the mean of the logged data; it is always smaller than the arithmetic mean.

Grading – The cutting and/or filling of the land surface to a desired slope or elevation.

Harvest and Use Low-Impact Development Treatment Control Measures (Harvest and Use LID Treatment Control measure) – A subcategory of treatment control measures that harvests and uses the design capture volume or quantified portion thereof.

The captured volume is typically used for non-potable uses such as toilet-flushing, industrial process supply, and landscape irrigation.

Hazardous Substance – Any substance designated under 40 CFR part 116 pursuant to section 311(b)(2) of the Clean Water Act (40 CFR § 122.2).

Hazardous Waste – Defined as set forth in California Code of Regulations, title 22, section 66261.3.

Hydrologic Condition of Concern (HCOC) – A condition of a stream or channel, or some reach thereof, or a condition of some other waterbody (e.g., a vernal pool), where its hydrology is, or is proposed to be, altered by past or future development such that there has been, or could be, cumulatively significant adverse impacts to the physical or biological integrity of the waterbody.

Hydromodification – The alteration of the hydrologic characteristics of coastal and noncoastal waters, which in turn could cause degradation of water resources (USEPA 2007).

Illicit Connection – Any connection to the MS4 that is prohibited under local, state, or federal statutes, ordinances, codes, or regulations. The term illicit connection includes all non-stormwater discharges and connections except discharges pursuant to an NPDES

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permit, discharges that are identified in section VII, Effluent Limitations and Discharge Specifications, of Order No. R8-2024-0001, and discharges authorized by the Executive Officer.

Illicit Discharge – Any discharge to the MS4 that is not composed entirely of stormwater, except discharges pursuant to an NPDES permit, discharges that are identified in section IV of Order No. R8-2024-0001, and discharges authorized by the Executive Officer. (See 40 CFR § 122.2(b)(2))
Impervious Surface – That part of a developed parcel that has been modified to substantially preclude the land’s ability to absorb and hold rainfall. It includes hard surfaces which cause water to run off the surface in greater quantities or at an increased rate of flow from the flow that existed under natural conditions prior to development. For example, common impervious surfaces include, but are not limited to, rooftops, walkways, patios, courtyards, driveways, parking lots, storage areas, concrete or asphalt paving, gravel roads, or any cleared, graded, graveled, paved, or compacted surfaces, or other surfaces which similarly impede the infiltration of surface water into the soil.

Implementation Agreement – The Implementation Agreement establishes the responsibilities of each Permittee and a procedure for funding the shared costs.

Industrial Site - Any site where industrial infrastructure and ancillary works are located and zoned by the city for industrial use rather than residential or commercial needs. This includes but is not limited to sites requiring coverage under the Industrial General Permit.

Industrial General Permit – State Water Board Order No. 2014-0057-DWQ (NPDES No.

CAS000001) or the most recent General Permit for Stormwater Discharges Associated with Industrial Activities issued by the State Water Board subsequent to this Order.

Infiltration – The flow of water into the soil by crossing the soil surface.

Infiltration Low-Impact Development Treatment Control Measure (Infiltration LID Treatment Control measures) – A type of LID treatment control measure that employs infiltration at the principal mechanism for the loss of the design capture volume or quantified portion thereof.

Isopluvia – A line on a map drawn through geographical points having the same pluvial (rain, precipitation) index.

Iterative Process - The practice of building, refining, and improving a project, product, or initiative. The purpose of an iterative process is to continually improve to ultimately achieve some decision or desired outcome. An iterative process is typically applied in circumstances where there is great uncertainty; where costs of errors are high; or where a full commitment of resources to achieve a risky outcome is undesirable. This Order requires the execution of an iterative process for the continual improvement of projects and programs, Watershed Management Plans, and the Monitoring and Reporting Program during the permit term to achieve compliance with the WQBELs and receiving

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water limitations. The iterative process is driven by a set of permit provisions in section III.A. that require the Permittees to establish objective performance metrics that provide feedback on the performance of their BMPs and make improvements.

Land Disturbance – The clearing, grading, excavation, stockpiling, or other construction activity that results in the possible mobilization of soils or other pollutants into the MS4.

This specifically does not include routine maintenance activity to maintain the original line and grade, hydraulic capacity, or original purpose of the facility. This also does not include emergency construction activities required to protect public health and safety.

LID Treatment Control Measure – A subcategory of treatment control measures. They are further sub-classified into retention LID treatment control measures that employ harvest and use, evaporation/ transpiration, infiltration, or any combination thereof, and biotreatment control measures that employ biological uptake, transformation, or degradation of pollutants and incidental infiltration and evapotranspiration.

Load Allocation (LA) – The portion of a receiving waterbody's loading capacity that is attributed either to one of its existing or future nonpoint sources of pollution or to natural background sources in a TMDL. Load allocations are best estimates of the loading, which may range from reasonably accurate estimates to gross allotments, depending on the availability of data and appropriate techniques for predicting the loading. Wherever possible, natural and nonpoint source loads are distinguished. (40 CFR § 130.2(g)) Low Impact Development (LID) – A stormwater management and land development strategy that combines a hydrologically functional pollution prevention measures to compensate for land development impacts on hydrology and water quality. LID techniques mimic the site’s predevelopment hydrology by using techniques that store, infiltrate, evapotranspire, bio-filter, or detain runoff close to its source.

Maximum Extent Practicable (MEP) - The technology-based discharge standard for MS4s established by CWA section 402(p).

Municipal Separate Storm Sewer System (MS4) – A conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains): (i) Owned or operated by a State, city town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes; (ii) Designated or used for collecting of conveying stormwater; (iii) Which is not a combined sewer; (iv) Which is not part of the Publicly Owned Treatment Works (POTW) as defined at 40 CFR section 122.2 (40 CFR § 122.26(b)(8))
National Pollutant Discharge Elimination System (NPDES) Permit – A permit issued under section 402 of the Clean Water Act for regulation of discharges of pollutants from point sources to waters of the United States.

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New Development – The categories of development identified in section VIII of this Order. New development does not include routine maintenance to maintain original line and grade, hydraulic capacity, or original purpose of a facility, nor does it include emergency new development required to protect public health and safety. Dischargers should confirm with Santa Ana Water Board staff whether a particular routine maintenance activity is subject to this Order.

Non-critical Milestone – An action or event marking a significant stage in the process of WMP development and implementation. Unlike critical milestones, non-critical milestones are not subject to enforcement but must be reported. The distinction between types of milestones is intended to facilitate transparent and more detailed disclosure of the progress of WMP development and implementation and allow early detection of deviations in a schedule that could lead to violations.

Non-point Source – Non-point sources are any source of discharge of pollutants that does not meet the definition of a point source under CWA section 502(14).

Non-stormwater Runoff – All discharges to and from an MS4 that do not originate from precipitation events (i.e., all discharges to an MS4 other than stormwater). Nonstormwater runoff includes illicit discharges, non-prohibited discharges, and NPDES permitted discharges.

Nuisance – Anything which meets all the following requirements: 1) Is injurious to health, or is indecent, or offensive to the senses, or an obstruction to the free use of property as to interfere with the comfortable enjoyment of life or property. 2) Affects at the same time an entire community or neighborhood, or any considerable number of persons, although the extent of the annoyance or damage inflicted upon individuals may be unequal. 3) Occurs during, or results from, the treatment or disposal of wastes (Wat. Code, § 13050(m))
Open Space – Any parcel or area of land or water that is essentially unimproved or devoted to an open-space use for the purposes of (1) the preservation of natural resources, (2) the managed production of resources, (3) outdoor recreation, or (4) public health and safety (Riverside County General Plan adopted October 7, 2003. Technical Appendix A, Glossary).

Outfall – A point source as defined by 40 CFR section 122.2, at the point where a MS4 discharges to waters of the United States. An outfall does not include open conveyances connecting two municipal separate storm sewers. An outfall does not include pipes, tunnels, or other conveyances which connect segments of the same stream or other waters of the U.S. and are used to convey waters of the U.S. (40 CFR §122.26 (b)(9)) Permit Area – Areas that are under the jurisdiction of the Santa Ana Regional Water Quality Control Board. These include north and northwestern portions of Orange County, north and western portions of Riverside County and western portions of San Bernardino County. See the Basin Plan for a detailed description of the Santa Ana Region boundaries as well as Water Code section 13200(e). The Permit Area is identified on Attachment B.

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Permittees – The Cities and County Agencies listed in Table 1 of this Order (Order No.

R8-2024-0001).

Point Source – Any discernible, confined, and discrete conveyance, including, but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, landfill leachate collection systems, vessel, or other floating craft from which pollutants are or may be discharged. This term does not include return flows from irrigated agriculture or agricultural stormwater runoff. (40 CFR § 122.2; see also 33 USC § 1362(14))
Pollutant – As defined in section 502(6) of the CWA, any dredged spoil, solid waste, incinerator residue, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial, municipal, and agricultural waste discharged into water. (33 USC § 1362(6))
Pollution – The alteration of the quality of the waters of the State by waste to a degree that unreasonably affects either of the following: 1) the waters for beneficial uses; or 2) facilities that serve these beneficial uses. Pollution may include contamination. (Wat.

Code, §13050(l))
Post-Construction Control Measures – A subset of control measures including source and treatment control measures which detain, retain, filter, or educate to prevent the release of pollutants to surface waters during the final functional life of development.

Principal Permittee – The County of Orange for Orange County; Riverside County Flood Control and Water Conservation District (RCFC&WCD) for Riverside County; and San Bernardino County Flood Control District (SBCFCD) for San Bernardino County.

Priority Land Uses – Those developed sites, facilities, or land uses (i.e., not simply zoned land uses) within the MS4 Permittee’s jurisdiction as follows:

1. High-density residential: all land uses with at least ten (10) developed dwelling units/acre.

2. Industrial: land uses where the primary activities on the developed parcels involve product manufacture, storage, or distribution (e.g., manufacturing businesses, warehouses, equipment storage lots, junkyards, wholesale businesses, distribution centers, or building material sales yards).

3. Commercial: land uses where the primary activities on the developed parcels involve the sale or transfer of goods or services to consumers (e.g., business or professional buildings, shops, restaurants, theaters, vehicle repair shops, etc.).

4. Mixed urban: land uses where high-density residential, industrial, and/or commercial land uses predominate collectively (i.e., are intermixed).

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5. Public transportation stations: facilities or sites where public transit agencies’ vehicles load or unload passengers or goods (e.g., bus stations and stops).

Priority Projects – New development and redevelopment project categories listed in section VIII.B of Order No. R8-2024-0001.

Receiving Waters – A water of the United States into which waste and/or pollutants are or maybe be discharged.

Receiving Water Limitation – Any applicable numeric or narrative water quality objective or criterion, or limitation to implement the applicable water quality objective or criterion, for the receiving waters as contained in the Water Quality Control Plan for the Santa Ana Region (Basin Plan), water quality control plans or policies adopted by the State Water Board, or federal regulations, including but not limited to, 40 CFR section 131.38.

Report of Waste Discharge (ROWD) – Application for issuance or re-issuance of WDRs under Water Code section 13376 and/or Water Code section 13260.

Retention Low-Impact Development Treatment Control Measures (Retention LID treatment Control Measures) – A subcategory of treatment control measures that employ retention of the design capture volume or a quantified portion thereof. The retained volume is infiltrated, evaporated, evapotranspired, or used (typically for nonpotable uses).

Routine Maintenance – work performed on a regular, recurring basis that is necessary to delay or prevent the failure of physical properties so that they are serviceable for their original purpose. Routine maintenance applies to the replacement of components that are subject to expected wear during normal use, such as pavement surfaces, structural coatings, roof tiles, shingles, top coats, and aggregate surfaces. Routine maintenance excludes replacement of structures or replacement of a structure’s components specifically when such replacement is not expected until the end of their service life or a catastrophic failure due to earthquake, fire, or similar unexpected event occurs.

Runoff from MS4s – Runoff is defined as all flows in a stormwater conveyance system from urban areas, which include residential, commercial, industrial, and construction areas. Runoff consists of the following components: (1) stormwater runoff and (2) authorized non-stormwater discharges (see section IV of this Order). Runoff from MS4s does not include runoff from undeveloped open space, feedlots, dairies, farms, and agricultural fields.

Sanitary Sewer Overflow (SSO) – Any overflow, spill, release, discharge, or diversion of untreated or partially treated wastewater from a sanitary sewer system.

Santa Ana Region – Area under the jurisdiction of the Santa Ana Water Board, defined in Water Code section 13200(e) and is shown on Attachment B.

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Santa Ana Water Board – California Regional Water Quality Control Board, Santa Ana Region.

Scrap Metal Permit – Santa Ana Water Board Order No. R8-2018-0069 (NPDES No.

CAG618001) or the most recent Sector-Specific Scrap Metal Recycler NPDES Stormwater Permit issued by the Santa Ana Water Board subsequent to this Order.

Significant Redevelopment – As defined in section VIII of Order No. 2024-0001.

Source Control Measures – In general, activities or programs to educate the public or provide low-cost non-physical solutions, as well as facility design or practices aimed to eliminate or minimize the contact between potential pollutants and stormwater or authorized non-stormwater to prevent the transport of pollutants to receiving waters.

Some examples include activity schedules, prohibitions of practices, street sweeping, facility maintenance, detection and elimination of IC/IDs, and other source control measures. Facility design examples include providing attached lids to trash containers, canopies for fueling islands, secondary containment, or roof or awning over material and trash storage areas to prevent direct contact between water and pollutants.

Standard Industrial Classification (SIC) Code – Four-digit industry code, as defined by the US Department of Labor, Occupational Safety and Health Administration. The SIC Code is used to identify if a facility requires coverage under the Industrial General Permit.

Stormwater Runoff – Any kind of runoff from a precipitation event, including stormwater runoff, snowmelt runoff, and surface runoff and drainage. (See 40 CFR § 122.26(b)(13)) Stormwater General Permits – The Industrial General Permit (State Water Board Order No. 2014-0057-DWQ, NPDES No. CAS000001), Construction General Permit (State Water Board Order No. 2009-0009-DWQ, NPDES No. CAS000002), and sector-specific Scrap Metal Permit (Order No. R8- 2018-0069) as amended or revised.

Stormwater Ordinance – The Stormwater Runoff Management and Discharge Control Ordinances and ordinances addressing grading and erosion control adopted by the Permittees.

Stormwater Pollution Prevention Plan (SWPPP) – A plan developed to minimize and control the discharge of pollutants from the industrial and construction sites to stormwater conveyance systems. The plan must identify pollutant sources, control measures for each pollutant source, good housekeeping practices, and employee training programs.

Substantial Evidence – Enough relevant information and reasonable inferences from this information that a fair argument can be made to support a conclusion. This includes facts, reasonable assumptions predicated on facts, or expert opinion supported by facts, but does not include argument, speculation, unsubstantiated opinion or narrative, or evidence which is clearly erroneous or inaccurate. (See Pub. Res. Code, § 21080(e)(2))

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Technology-Based Effluent Limitation (TBEL) — An effluent limitation for a pollutant that is based on the capability of a treatment method to reduce the pollutant to a certain concentration or mass loading level.

TMDL Implementation Plan – The component of a TMDL that describes actions, including monitoring, needed to reduce pollutant loadings and a timeline for implementation. TMDL implementation plans can include a monitoring or modeling plan and milestones for measuring progress, plans for revising the TMDL if progress toward cleaning up the waters is not made, and the date by which water quality standards will be met (USEPA Final TMDL Rule: Fulfilling the Goals of the CWA, EPA 841-F-00-008, July 2000).

Total Maximum Daily Load (TMDL) – Numerical calculations of the maximum amount of a pollutant that can be discharged into a waterbody from all contributing loads (point source, non-point source, background contribution, margin of safety) and still maintain water quality standards. Under Clean Water Act section 303(d), TMDLs must be developed for all waterbodies that do not meet water quality standards after application of technology-based controls.

Toxic Pollutant – A pollutant that can cause toxicity, as listed under section 307(a) of the CWA.

Toxicity – Adverse responses of organisms to chemicals or physical agents ranging from mortality to physiological responses such as impaired reproduction or growth anomalies.

Trash – 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. Trash is not considered to be leaf litter or plant material.

Treatment Control Measures - Any system designed and constructed to reduce or remove pollutants from urban runoff. Pollutants are removed by simple gravity settling of particulate pollutants, filtration, biological uptake, media adsorption or any other physical, biological, or chemical process. In this Order, structural treatment control measures are a subset of treatment control measures that treat the design capture volume or flow or a portion thereof according to published and generally accepted engineering criteria.

Structural treatment control measures are further sub-classified into LID treatment control measures and non-LID treatment control measures. LID control measures are further sub-classified into Retention LID treatment control measures and Biotreatment Control Measures. All of these classes of treatment control measures are subject to general and specific requirements in this Order. Examples include secondary containment, treatment measures, (e.g. first flush diversion, detention/retention basins, and oil/grease separators), run-off controls (e.g., grass swales, infiltration trenches/basins, etc.), and engineering and design modification of existing structures.

Waste – Includes sewage and any and all other waste substances, liquid, solid, gaseous, or radioactive, associated with human habitation, or of human or animal origin, or from

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any producing, manufacturing, or processing operation, including waste placed within containers of whatever nature prior to, and for purposes of, disposal. (Wat. Code, §13050(d))
Waste Discharge Requirements (WDRs) – As defined in Water Code section 13374, the term “Waste Discharge Requirements” is the equivalent of the term "permits" as used in the federal CWA, as amended. The Santa Ana Water Board usually uses the term “permit” to refer to WDRs for discharges to waters of the U.S.

Waste Load Allocation (WLA) – The portion of a receiving waterbody's loading capacity that is allocated to one of its existing or future point sources of pollution in a TMDL (40 CFR § 130.2(h)).

Water Quality Management Plan (WQMP) – A WQMP documents mitigation of stormwater pollutants and hydrological impacts of a priority project that is subject to a Permittee’s discretionary approval. A WQMP contains information related to site characteristics, expected pollutants, hydrology impacts, incorporated structural and source control measures, Low Impact Development (LID) design features, operation and maintenance, and public education and training. The collective information is intended to describe how the project will minimize water quality impacts to downstream waterbodies.

WQMPs have been required for priority projects in MS4 permits issued in the Santa Ana Region starting in 2002.

Water Quality Objective – A numeric or narrative limit established for the reasonable protection of beneficial uses of water or the prevention of nuisance within a specific area (Wat. Code, § 13050(h)). “Water quality objectives” are equivalent to “criteria” under federal law. (See 40 CFR §131.3)
Water Quality Standards – Consist of beneficial uses, water quality objectives/criteria to protect those beneficial uses, and the state and federal antidegradation policies. Water quality standards are found in regional and statewide water quality control plans. The USEPA has also adopted water quality criteria for California in the National Toxics Rule and California Toxics Rule.

Water Quality-Based Effluent Limitation (WQBEL) – An effluent limitation determined by selecting the most stringent of the effluent limitations calculated using all applicable water quality criteria (e.g., aquatic life, human health, wildlife, translation of narrative criteria) for a specific point source to a specific receiving waterbody.

Waterbody/Pollutant Combination - Each pollutant causing a waterbody to be impaired or threatened is referred to as a waterbody/pollutant combination. Typically, a TMDL is developed for each waterbody/pollutant combination placed on Clean Water Act section 303(d) list of impaired waters.

Waters of the State – Any surface water or groundwater, including saline waters, within the boundaries of the State (Wat. Code, § 13050(e)). Waters of the State include waters of the United States.

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Waters of the United States – “Navigable waters” under the CWA (33 U.S.C. § 1362(7)) as defined in 40 CFR section 122.2, which as of the date of issuance of this Order incorporates the definition in 40 CFR section 120.2 and shall include any revised definitions upon their effective dates.

Watershed – That geographical area which drains to a specified point on a water course, usually a confluence of streams or rivers (a drainage area, catchment, or river basin).

Watershed Management Plan (WMP) – A voluntary, alternative compliance pathway to comply with receiving water limitations and water quality-based effluent limitations that meets the requirements of section XII of Order No. R8-2024-0001. Under a WMP, a Permittee or group of Permittees develops a comprehensive program on a watershed scale through customized strategies, control measures, and BMPs.

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Attachment B
Figures
(Provided for Illustration Purposes Only)

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Figure B.1: Santa Ana Water Board Watershed Managements Areas

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Figure B.2: Orange County Permittees

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Figure B.3: Riverside County Permittees

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Figure B.4: San Bernardino County Permittees

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Attachment C
Monitoring & Reporting Program

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Attachment C

STATE OF CALIFORNIA

CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD

SANTA ANA REGION
3737 Main Street, Suite 500, Riverside, CA 92501-3348
(951) 782-4130 Fax (951) 781-6288
http://www.waterboards.ca.gov/santaana
MONITORING AND REPORTING PROGRAM R8-2024-0001
FOR
ORDER R8-2024-0001
NPDES PERMIT NO. CAS618000
Revision No. Date Requested Approval Date

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I. General
A. Section 308 of the federal Clean Water Act (CWA) and 40 Code of Federal Regulations (CFR) sections 122.41(h), (j)-(l), 122.44(i), and 122.48 require that all NPDES permits specify monitoring and reporting requirements. Federal regulations applicable to large and medium MS4s also specify additional monitoring and reporting requirements. (40 CFR § 122.26(d)(2)(i)(F) & (d)(2)(iii)(D), 122.42(c)) Water Code section 13383 also authorizes the Santa Ana Water Board to establish monitoring, inspection, entry, reporting, and recordkeeping requirements. This Monitoring and Reporting Program (MRP) establishes monitoring, reporting, and recordkeeping requirements that implement the federal and California laws and/or regulations.

B. The requirements of this MRP may be satisfied in whole or in part through the Permittees’ collaborative efforts and participation in national, state-wide, regional, or local monitoring programs, subject to the discretion of the Executive Officer. The Permittees shall continue to cooperate with other MS4 Permittees and other public or private organizations in the watershed to develop coordinated surface water quality monitoring programs, databases, and special studies, as appropriate. The Permittees may use coordinated, regional monitoring programs conducted by the TMDL Task Forces to address, in whole or in part, as appropriate, the requirements of this MRP. These external monitoring programs must be expressly incorporated into the Program Monitoring and Reporting Plan (PMRP) in section IV below, to satisfy the requirements of this MRP.

C. The Executive Officer is authorized to add monitoring requirements to the MRP.

The Executive Officer will provide a minimum of 30 days for public review prior to approving any proposed changes.

D. To avoid duplication of effort, monitoring work performed by parties other than the Permittees, or work carried out by the Permittees in support of other programs, may be substituted for work required by the MRP. Substitutions are allowed provided that they meet the requirements of the MRP, Order R8-2024-0001, and are approved by the Executive Officer pursuant to Order R8-2024-0001.

E. The Permittees may supplement monitoring data that is required to be collected as part of this MRP and subsequent amendments with other data sources.

Supplemental data must be used for the purpose of improving any related analysis and is subject to the approval of the Executive Officer.

F. The Santa Ana Water Board has approved various monitoring programs as part of TMDLs (see the description in the Fact Sheet). Where there is a conflict between those monitoring programs and this MRP, with respect to the Permittees, this MRP shall prevail.

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G. Each Permittee is responsible for the accuracy and completeness of the monitoring program(s) and related products for the watershed(s) to which the Permittee charges. However, the Principal Permittees may develop and implement those programs and submit related work products on behalf of the Permittees within their jurisdiction.

H. Unless otherwise specified, the Permittees shall upload all ambient water quality monitoring data and associated field, station, and quality assurance data into the California Environmental Data Exchange Network (CEDEN), or its successor, not less than annually, unless otherwise directed by the Executive Officer. Information adequate to verify the success of the upload shall be included in the Annual Progress Report.

I. The CWA provides that any person who falsifies, tampers with, or knowingly renders inaccurate any monitoring device or method required to be maintained under this Order shall, upon conviction, be punished by a fine of not more than $10,000, or by imprisonment for not more than two years, or both. If a conviction of a person is for a violation committed after a first conviction of such person under this paragraph, punishment is a fine of not more than $20,000 per day of violation, or by imprisonment of not more than four years, or both. (40 CFR § 122.41(j)(5)) J. Permittees must submit all information and materials necessary to comply with the requirements of Order R8-2024-0001 to the Principal Permittees in a timely manner.

K. All reports submitted to the Santa Ana Water Board pursuant to the requirements of Order R8-2024-0001 must include a statement identifying the provision(s) with which the report is intended to comply.

II. Water Quality Monitoring Requirements
A. Goals
The Permittees must carry out water quality monitoring that is adequate to achieve the following goals:

1. Characterize the water quality condition with respect to water quality standards; identify trends; and identify pollutants found in runoff that may cause or contribute to impairments or exceedances of water quality standards.

2. Determine if waste load allocations assigned to the Permittees are being exceeded.

3. Demonstrate attainment of waste load allocations using methods that have been approved by the Executive Officer. Such methods may include TMDL

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targets, combined waste load allocations and load allocations, or other alternative indicators.

4. Identify and quantify other sources of pollutants (e.g., atmospheric deposition, legacy pollutants, etc.) that may adversely affect the beneficial uses of receiving waters.

5. Identify those receiving waters which, without additional action to control pollution from runoff, cannot reasonably be expected to attain or maintain applicable water quality standards.

B. General Water Quality Monitoring Requirements

1. All sample collection, handling, storage, and analysis must be completed in conformance with 40 CFR 136; unless another test procedure is required under 40 CFR subchapter N or another method is specified in this MRP. If analytical methods are not identified in 40 CFR part 136 or specified in this MRP, then the Executive Officer may approve the use of alternative analytical methods for compliance purposes. These alternative analytical methods shall be validated methods published by consensus standards bodies (USEPA, Standard Methods for the Examination of Water and Wastewater [Standard Methods], American Society of Testing Materials [ASTM], or Association of Official Analytical Chemists [AOAC]) or a performance-based method that is validated based upon the protocols described in USEPA’s Guide to Methods Flexibility and Approval of EPA Water Method (USEPA, 1996). Performance-based method validation packages shall be approved by the Executive Officer.

2. Laboratories used to analyze monitoring samples must be certified by the State Water Resources Control Board’s Division of Drinking Water, Environmental Laboratory Accreditation Program (ELAP), and must include quality assurance/ quality control (QA/QC) data with their reports.

3. Calculations for all limitations must be performed using published and generally accepted methods.

4. The sampling method, practice, and analysis must minimize bias.

5. Field instruments used to test water quality parameters must be calibrated according to the manufacturer's instructions.

6. Water quality parameters that are tested using valid field instruments are not required to be analyzed by a laboratory.

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7. Wet weather monitoring events must be separated by a minimum of 72 hours of dry weather (no precipitation) in accordance with 40 CFR section 122.21(g)(7)(ii).

8. Permittees must employ sample collection methods that support regional comparisons of data unless site conditions make alternate methods necessary.

9. Data transmittals on the results of water quality monitoring to the Santa Ana Water Boards must be in a standard format for all data transfers and should allow data to be universally shared and evaluated as part of various programs.

10.For each monitoring location and event, the Permittees must record observed conditions or circumstances that may influence monitoring results or affect conclusions made from the monitoring data.

11.Locations and frequencies of monitoring that is performed to demonstrate compliance with the WQBELs in Appendices 2 through 13 of Order No. R8- 2024-0001 must be consistent with the locations and frequencies specified in the relevant TMDL and, as appropriate, any approved TMDL monitoring plans.

12.Permittees must test for additional pollutants that are known or suspected of contributing to the impairment of the beneficial uses of the receiving waters at the direction of the Executive Officer.

13.Permittees must test for additional parameters that may provide information on the distribution and abundance of pollutants and their sources.

C. Outfall Monitoring Requirements

1. Permittees must perform monitoring of runoff during wet and dry weather conditions at representative outfall locations that have been approved by the Executive Officer.

2. Permittees must document the date and duration of the storm events sampled, estimates of the volume of rainfall from the storm event which generated the sampled discharge, the duration between the storm events sampled, and the end of the previous measurable storm event.

D. Toxicity Testing

1. Except for discharges to ocean waters, Permittees must perform acute and chronic aquatic toxicity testing. Testing must be performed according to the State Policy for Water Quality Control: Toxicity Provisions (adopted December 1, 2020, revised October 5, 2021).

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a. Chronic and acute aquatic toxicity tests shall be conducted using one or more of the test species identified in Table 1 of the Toxicity Provisions.

Permittees must select test species as described in section III.B.2 of the Toxicity Provisions.
b. Chronic aquatic toxicity testing methods are identified in 40 CFR, part 136, or other U.S. EPA-approved methods, or included in the following U.S. EPA method manuals: Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, Fourth Edition (EPA-821-R-02-013); Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Marine and Estuarine Organisms, Third Edition (EPA-821-R-02-014); and Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to West Coast Marine and Estuarine Organisms, First Edition (EPA-600-R-95-136). c. Acute aquatic toxicity testing methods shall follow methods identified in 40 CFR, part 136, or other U.S. EPA-approved methods, or included in Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, Fifth Edition (EPA-821-R-02-012).

2. Toxicity testing shall be evaluated and reported using Percent Effect as outlined in sections III.B.3 through 5 of the Toxicity Provisions.

E. Illicit Discharge Detection and Elimination

1. The Permittees must monitor to effectively detect and prohibit illicit connections and illegal discharges.

2. The Permittees must use odor, color, clarity, unusual wildlife morbidity or mortality, sheen, staining, corrosion, unnatural deposits, and other subjective indicators to identify suspected illicit connections or illegal discharges.

F. Receiving Waters Monitoring Requirements

1. Permittees must perform representative monitoring of the receiving waters to which outfalls in section II.C discharge.

2. Receiving waters monitoring must include, at a minimum, all parameters enumerated for sediment monitoring in the Sediment Quality Provisions of the Water Quality Control Plan for Enclosed Bays and Estuaries of California.

G. Bioassessment Monitoring Requirements

1. Each Principal Permittee must conduct or cause bioassessments to occur within their counties to identify stressors of biological conditions and to enable

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the identification of specific actions to be taken to meet the goals identified in section II.A.

2. In lieu of developing an independent bioassessment program, the Permittees may participate (through a memorandum of understanding and cooperative agreements) with other organizations in conducting bioassessment on a regional basis.

3. Bioassessment monitoring must be conducted in conformance with the Surface Water Ambient Monitoring Program’s (SWAMP) Quality Assurance Program, including the QAPrP and applicable QAPPs and standard operating procedures (SOPs).

4. Stressors must be identified using USEPA Stressor Identification Guidance Document (2000), the web-based Causal Analysis/Diagnosis Decision Information System (CADDIS), or a published and generally accepted method acceptable to the Executive Officer.

5. Bioassessment monitoring must be completed at the monitoring locations specified by the most recent SMC Workplan. The monitoring locations and parameters may be adjusted during the monitoring year according to recommendations. from the SMC so that they are consistent with the SMC Workplan.

6. Each Principal Permittee must complete a minimum of one causal assessment during the term of Order No. R8-2024-0001 to identify the likely causes of degraded biological conditions at one or more of the selected monitoring locations. Causal assessments must be conducted according to guidance acceptable to the Executive Officer or, where appropriate, the USEPA’s Causal Analysis/Diagnosis Decision Information System (CADDIS).

III. Special Studies
A. The Permittees should have an effective strategy for carrying out special studies. Special studies include projects intended to contribute to stormwater science or to support continual improvement of the Permittees’ stormwater program. Special studies do not include projects intended to reach conclusions on compliance with receiving water limitations or waste load allocations; such projects may be subject to the requirements of this MRP. This strategy should include:

1. A strategic plan that identifies research priorities.

2. Specific management questions to be informed by the results of the special study and which, when answered, will affect decisions in the program.

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3. Funding strategies which may include partnerships with other agencies, grants, etc.

4. An annual workplan for carrying out special study projects.

IV. Data Analyses
A. All sample collection, handling, storage, and analysis must be completed in conformance with 40 CFR 136, unless another test procedure is required under 40 CFR subchapter N, or another method is specified in this MRP. If analytical methods are not identified in 40 CFR part 136 or specified in this MRP, then the Executive Officer may approve the use of alternative analytical methods for compliance purposes. These alternative analytical methods shall be validated methods published by consensus standards bodies (USEPA, Standard Methods for the Examination of Water and Wastewater [Standard Methods], American Society of Testing Materials [ASTM], or Association of Official Analytical Chemists [AOAC]) or a performance-based method that is validated based upon the protocols described in USEPA’s Guide to Methods Flexibility and Approval of EPA Water Method (USEPA, 1996). Performance-based method validation packages shall be approved by the Executive Officer.

B. Permittees shall use sufficiently sensitive analytical test methods that are consistent with 40 CFR Parts 122 and 136, and 40 CFR chapter I, subchapter N.

C. If the analysis of monitoring results is inconclusive or reveals opportunities for improvements to the monitoring program, the Permittees must include recommendations to improve the effectiveness of the monitoring program in the Annual Progress Report.

D. All analyses must include an assessment of the reliability of its methods and conclusions. The assessment must be performed by or under the direction of qualified persons.

E. The Permittees must disclose areas of uncertainty in the analysis of monitoring data and related conclusions. The disclosure must be adequate to allow a reasonable independent assessment of the validity of the methods and conclusions. Areas of uncertainty include but are not limited to variance in sample or population data; error in measurements, calculations, or estimates; levels of confidence in the accuracy of values; and factors that are unmeasured or unmeasurable.

V. Program Monitoring Requirements
A. Goals

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Program monitoring consists of actions taken to track and control projects and programs carried out to comply with the requirements of Order R8-2024-0001.

Each Permittee must implement program monitoring that is adequate to achieve the following goals:

1. To collect data that is adequate to evaluate the effectiveness of individual or systems of source control and treatment control measures and best management practices used to control pollution based on the application of objective performance metrics.

2. To detect deviations from the intended scope, schedule, and levels of effort for project and program activities.

3. To detect changes in strategies and tactics used in project and program activities.

4. To document the conditions of projects and programs under which receiving water limitations and waste load allocations are attained and, if feasible, establish causal relationships.

B. Program Effectiveness Assessments

1. Each Permittee must perform assessments of the effectiveness of their program(s) to attain WQBELs and receiving water limitation according to the requirements of Order R8-2024-0001. Assessments must be performed annually or according to a schedule approved by the Executive Officer as part of the PMRP. Reported outcomes must be expressly compared to:
a. The performance metrics prescribed by Order R8-2024-001 b. The performance metrics developed by the Permittees.

VI. Program Monitoring and Reporting Plan (PMRP)
A. The Permittees must implement monitoring and reporting that is required by this MRP according to a PMRP that has been approved by the Executive Officer pursuant to Order R8-2024-0001. A PMRP must satisfy the goals, requirements, and specifications described in this MRP and Order R8-2024-0001. The Permittees may develop a new PMRP or revise existing monitoring plans.

1. A PMRP must be written in an instructive manner for the benefit of persons responsible for its implementation.

2. The initial draft or revised PMRP must be submitted for approval to the Executive Officer within 18 months of the effective date of Order R8-2024-0001.

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3. The responsible Permittees shall provide any information that is missing, or requested in writing by the Executive Officer, by the date identified in the request.

4. The Executive Officer will provide a minimum public review period of 30 days prior to approving the PMRP.

B. A PMRP must include the following:

1. The water quality monitoring objectives that will be assessed; descriptions of the locations and schedules for the receiving waters, outfall, and sediment monitoring; the parameters to be analyzed; sampling and analytical methods; minimum number of replicates for toxicity testing; reporting limits; and required reporting units.

2. The measurement quality objectives; standard operating procedures for sample collection, sample analysis, data review and verification; and other topics as needed.

3. A decision tree for data use and qualifying data used when measurement quality objectives are not achieved. Data that does not meet the measurement quality objectives established in the PMRP shall be qualified with standardized data quality flags (e.g., CEDEN QA codes).

4. All the elements of a Quality Assurance Project Plan (QAPP) as outlined in section 6.1.4 of the Water Quality Control Policy for Developing California’s Clean Water Act section 303(d) List. The elements must ensure that data of known quality and quantity are collected to satisfy the goals, requirements and specifications described in this MRP and Order R8-2024-0001. The Quality Assurance Project Plan (QAPP) or monitoring plan documents for any joint monitoring programs shall be consistent with the QAPP elements of the PMRP.

5. A Data Management section that provides at a minimum:
a. Details of the data lifecycle from sample collection to data submission. b. The Santa Ana Water Board’s information management systems to which the data will be submitted, and information needed to query and retrieve data from the systems.
c. A data submission schedule.

6. Descriptions of the methods that will be used to demonstrate compliance with the WQBELs in Appendices 2 through 13 of Order R8-2024-0001, as revised or amended or as supplemented by a Basin Plan amendment, and the

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processes used to identify and report exceedances of applicable water quality standards. The descriptions of the methods must be sufficiently detailed to allow other stakeholders the ability to repeat them. The descriptions must include:
a. The statistical analyses that will be performed, the purpose of each analysis, the data sets and sub-sets that will be analyzed, and the time periods or thresholds at which each analysis will be performed.
b. The methods for interpreting the outcomes of the analyses.

7. A schedule of data collection, analyses, and reporting cycles to demonstrate compliance with the WQBELs in Appendices 2 through 13 and receiving water limitations.
a. The rationale for the schedule must be provided.
b. Cycles of monitoring, analysis, and reporting for each of the WQBELs and for receiving water limitations shall conform to the following:
i. A complete cycle must be as short as practicable to support continual improvements to the Permittees’ projects and programs to attain WQBELs or receiving water limitations; conform to applicable TMDL deadlines and assessment periods found in the Basin Plan and incorporated into Appendices 2 through 13; and must not exceed 5 years.
ii. A complete cycle should consider the availability of data and a reasonable period after which source control and treatment control measures and BMPs may affect water quality.

8. A schedule for assessments of the effectiveness of individual or systems of source control and treatment control measures and BMPs that will be performed by each Permittee. A separate schedule shall be provided for assessments of overall activities that are of mutual interest; these assessments will be performed by the Principal Permittees. The schedules will identify the timing of the assessments; the performance metrics that will be applied; and describe the methods of measuring effectiveness.

C. Until the draft PMRP is approved, the Permittees must continue their existing monitoring and reporting program as described in the most recent Annual Progress Report. Changes to this monitoring are prohibited except with the approval of the Executive Officer.

D. The Executive Officer is authorized to direct changes to the existing monitoring and reporting program and, following its approval, to the PMRP, through a written notice. Changes may include a reduction or increase in the number of

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parameters to be monitored, the frequency of monitoring, or monitoring locations, or the number of samples collected, and changes to the methods of demonstrating compliance with Waste Load Allocations or Receiving Water Limitations.

E. Permittees must complete the directed changes by the deadline provided in the Executive Officer’s notice.

F. The Permittees must evaluate the effectiveness of the PMRP in meeting the requirements of this MRP and propose changes annually. The proposed changes to the PMRP must be approved by the Executive Officer before becoming effective.

G. A PMRP may be amended by the Permittees only with the approval of the Executive Officer except for the following:

1. Corrections for inconsequential grammatical, typographical, or technical errors

2. Corrections or updates to cross-references.

3. Updates to Permittee roles or contact information.

G. The Permittees must fully implement a PMRP and any subsequent changes approved or directed by the Executive Officer. The Executive Officer is authorized to approve the PMRP and may set conditions for approval.

H. The Executive Officer will allow a minimum of 30 days for public review and comment before approving the PMRP or approving or directing subsequent changes.

I. The Principal Permittees must post notice of the availability of the approved PMRP on each County’s public website or using other media acceptable to the Executive Officer.

VII. Annual Progress Report Requirements
The Permittees must submit an Annual Progress Report to the Executive Officer of the Santa Ana Water Board no later than November 15th of each year. The reporting period is from July 1 to June 30, preceding each annual deadline. The Executive Officer may grant an extension of up to 60 days with cause upon the receipt of a written request from the Permittees prior to the November 15th deadline. The Annual Progress Report must include the following:

A. Water Quality Monitoring Results, Analyses, and Conclusions

1. The status of monitoring and analyses that were scheduled for the reporting period in the approved PMRP.

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2. The results and conclusions from analyses of the water quality monitoring data, performed according to the schedule in the approved PMRP.

3. The results of water quality monitoring that Permittees may have performed beyond the requirements of Order R8-2024-0001.

4. The results of the causal assessment performed pursuant to section II.F above.

5. Any related conclusions reached by the Permittees regarding achievement of the goals in section II.A above.

6. Information adequate to verify the success of the upload of data to the CEDEN or its successor.

B. Program Monitoring Reporting

1. A summary of changes made to the PMRP at the discretion of the Permittees.

2. A summary of changes to the PMRP that are proposed and changes that were approved by the Executive Officer during the reporting period. If no changes are proposed, the Executive Officer must be notified in the Annual Progress Report.

3. The results of each Permittees’ program effectiveness assessment. These results must be submitted by each Permittee to the Principal Permittee to allow for overall analyses of the programs’ effectiveness. The assessment results must include:
a. The performance metric(s) used to evaluate each individual or system of source and treatment control measures and best management practices. b. The source and treatment control measures and best management practice(s) that each performance metric assesses.
c. The method(s) of measurement.
d. Measured outcomes.
e. A qualitative assessment of the reliability of the methods of assessment, including disclosure of sources of uncertainty.
f. A summary of changes that have been executed or are planned for the assessment methods.

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4. The results of the Principal Permittee’s overall evaluation of the results of the program effectiveness assessments which are of mutual interest to the Permittees.

5. The outcomes of implementing the Permittees’ portfolio of projects and programs to control pollution.

6. Records of training provided to Permittees’ staff and others performing work on their behalf to that are adequate to demonstrate compliance with Order R8- 2024-0001.

7. The unified fiscal analysis (See section III.F of Order R8-2024-0001).

8. The maps of Permittees’ respective MS4s (see section IX.A.2.e of Order R8- 2024-0001)

9. A report on the status of special studies under section III above. The report must include a schedule of proposed actions, a description of work products to be completed, and the achievement of milestones along with any changes or updates for any special studies being carried out.

10.A report on any challenges to the legal authority of any Permittee that resulted in an adverse judgment in a court of law (See section III.D of Order No. R8- 2024-0001).

11.A report on the results of biennial reviews of mechanisms to provide efficiency and consistency in the Permittees’ WQMP-approval process (See section VIII.D of Order R8-2024-0001).

12.A report on the implementation and performance of any credit trading program pursuant to section VIII.H of Order R8-2024-0001.

13.A report on the outcomes of efforts to detect and mitigate SSOs pursuant to section IX.B of Order R8-2024-0001.

14.A report on conformance with the MS4 cleanout schedule and program accomplishments (See section XIV.B of Order R8-2024-0001).

15.Each Permittees’ inventory of fixed facilities and their prioritization category pursuant to section XIV.B of Order R8-2024-0001.

C. Trash Program Reporting

1. Each Permittee shall report their status towards compliance with section V of Order R8-2024-0001 in their Annual Progress Report, based on the Track that they selected, as indicated below:

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a. Track 1. Permittees that chose Track 1 as a method to comply must include the following information in their Annual Progress Report. i. All measures employed for the control of trash within their jurisdiction. ii. The status of all inspections and maintenance activities, including the results of any investigations due to third party complaints. iii. The estimated amount of trash discharged from representative MS4 outfalls from the previous year. This amount should be compared to previous years and an explanation shall be provided if the amount of trash discharged increased.
iv. The amount of trash in the MS4’s representative receiving water(s) from the previous year. This amount should be compared to previous year’s amount in the same representative receiving waterbody and an explanation shall be provided if the amount of trash discharged increased.
v. Submit a Geographic Information System (GIS) map and include the following information:
(a) Priority land uses.
(b) Equivalent alternative land uses.
(c) Total area and percentage area served by full capture systems. (d) Type and location of all existing and proposed full capture systems.
b. Track 2. Permittees that chose Track 2 as a method to comply must include the following information in their Annual Progress Report. i. The type, nature, and level of effort of source control and treatment control measures, best management practices, and multi-benefit projects have been used and the GIS-mapped locations where they were applied and the drainage area(s) served.
ii. The number of full capture systems installed (if any), their locations, and the individual and cumulative area served by them.
iii. The estimated amount of trash discharged from representative MS4 outfalls from the previous year. This amount should be compared to previous years and an explanation must be provided if the amount of trash discharged increased.

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iv. The estimated amount of trash in the MS4’s representative receiving water(s) from the previous year. This amount should be compared to previous years and an explanation shall be provided if the amount of trash discharged increased.
v. The status of all inspection and maintenance activities, including the results of any investigations due to third party complaints. vi. Updated jurisdictional map, if applicable, shall include the following information:
a. Priority land uses
b. Equivalent alternative land uses
c. GIS-mapped total area and percentage area served by full capture systems, multi-benefit projects, other treatment controls and institutional controls installed or utilized by the Permittee.
d. Type and GIS-mapped location of all existing and proposed full capture systems, multi-benefit projects, other treatment controls and institutional controls installed or utilized by the Permittee.

D. Watershed Management Plan Reporting

1. The status of achievement of critical and non-critical milestones and final deadlines described in Notices to prepare Watershed Management Plans and in final approved Watershed Management Plans according to section XII of Order R8-2024-0001.

2. Where a Watershed Management Plan has been approved, the responsible Permittees must also report:
a. The status of completion of proposed treatment control measures. b. The status of implementation of source control measures and best management practices.
c. The results of any monitoring undertaken to evaluate the impact of implementation of the Watershed Management Plan on receiving waters quality.

3. A summary of changes made to the WMP at the discretion of the Permittees.

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4. A summary of changes to the WMP that are proposed and changes that were approved by the Executive Officer during the reporting period. If no changes are proposed, the Executive Officer must be notified in the Annual Progress Report.

E. Annual Progress Report Format Standards

1. Annual Progress Reports shall be submitted in an electronic format subject to the approval of the Executive Officer. Electronic documents must be searchable and viewable using widely available software.

2. The Principal Permittees shall submit a plan for transmitting the contents of the Annual Progress Report information within 12 months of the effective date of Order R8-2024-0001. The plan will propose the process and method for normalizing Annual Progress Report data into the water boards’ information management systems (i.e., database normalization). The purpose of this plan is to align the permittees’ information management systems with the water boards’ systems, to facilitate conformance with USEPA’s Cross-Media Electronic Reporting Rule (CROMERR) and promote efficiency.

3. The Executive Officer may direct the Permittees to update the database normalization plan to improve efficiency, to comply with CROMERR, or in response to changes in technology.

VIII. Summary of Key Tasks and Deliverables
Table C.1, below, summarizes the schedule of key tasks and deliverables required by Order R8-2024-0001 and this MRP. Items are in the order of appearance in the Order. Table C.1 is provided for the convenience of the reader and should not be used as a substitute for reviewing the contents of the Order or this MRP. In the event of a conflict between the provisions and Table C.1, the provisions shall prevail.

Table C.1: Summary of Key Tasks and Deliverables
Task or
Deliverable Source Provision(s) Deadline
Report of Waste
Discharge
section I, Table 2, and
section II.D 180 days before expiration of this Order
Initial imminent
threat notice section III.E.1. a 24 hours after the Permittee’s discovery.

Imminent threat
report section III.E.1. b 5 business days after initial imminent threat notice.

Semi-annual
report on noncompliant
facilities
section III.E.4 January 31 and July 31 of each calendar year.

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Achieve Full
Trash Capture section V.D.2 By December 2, 2030.

Submit updated
Technical Guidance
Documents
section VIII.C.4 Within 18 months of the effective date of this Order
Create a WQMP
database section VIII.C.16 6 months from Order effective date.

Treatment control
measure waiver
notice
section VIII.H.e 30 -days prior to Permittee’s issuance of the waiver.

General audience
survey
section X.F 60 months from the date of adoption.

Submit notice of
intent to develop
Watershed
Management Plan
section XII.C
Within 90 days of the effective date of this
Order or within 90 days of receiving notice
of violation of receiving water limitations.

Program
Monitoring and
Reporting Plan
Attachment C, section
VI.A.2 18 months from date of adoption
Annual Progress
Report
section XV and Att. C
XII.B November 15th of each year
Plan for
transmitting
Annual Progress
Report
information
Attachment C, section
VII.E
Within 12 months of the effective date of
this Order.

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Attachment D
Fact Sheet

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Attachment D

STATE OF CALIFORNIA

CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD

SANTA ANA REGION
3737 Main Street, Suite 500, Riverside, CA 92501-3348
(951) 782-4130 □ Fax (951) 781-6288
http://www.waterboards.ca.gov/santaana

FACT SHEET
FOR
ORDER R8-2024-0001
NPDES NO. CAS618000

NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES) PERMIT

AND WASTE DISCHARGE REQUIREMENTS
FOR

DISCHARGES OF POLLUTANTS IN RUNOFF

FROM THE MUNICIPAL STORM SEWER SYSTEMS IN THE COUNTIES OF ORANGE,

RIVERSIDE, AND SAN BERNARDINO

WITHIN THE SANTA ANA REGION
SANTA ANA REGIONAL MS4 PERMIT
XXXX XX, 20XX

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I. PURPOSE .......................................................................................................................192 II. PERMIT INFORMATION...................................................................................................193 A. Permittees ................................................................................................................193 B. Permittee Designation of Board ................................................................................195 C. Permitted Discharges ...............................................................................................196 D. Permit Scope............................................................................................................196 E. Rationale for Regional Permit ...................................................................................197 III. FACILITY DESCRIPTION .................................................................................................198 A. Overview of the Hydrology of the Santa Ana Region ................................................198 B. Description of Receiving Waters and Watershed Management Areas ......................200 C. Description of the Permittees’ MS4s .........................................................................202 IV. APPLICABLE STATUTES, REGULATIONS, PLANS, AND POLICIES .............................203 A. Municipal Separate Storm Sewer System Requirements..........................................203 B. Federal and California Endangered Species Acts.....................................................204 C. California Environmental Quality Act.........................................................................204 D. Water Quality Control Plans......................................................................................204 E. National Toxics Rule (NTR) and California Toxics Rule ............................................206 F. Clean Water Act Section 303(d) List .........................................................................207 G. Antidegradation Policy ..............................................................................................207 H. Anti-backsliding Requirements .................................................................................222 I. Plain Language.........................................................................................................231 J. Other Regulations, Plans, and Policies .....................................................................231 K. Human Right to Water ..............................................................................................232 L. Assembly Bill 2108 ...................................................................................................232 V. RATIONALE FOR PERMITTEE RESPONSIBILITIES.......................................................232 A. Permittee Responsibilities.........................................................................................232 B. Implementation Agreement.......................................................................................233 C. Legal Authority/Enforcement.....................................................................................233 D. Notification Requirements.........................................................................................233 E. Fiscal Analysis..........................................................................................................234 F. Special Studies.........................................................................................................234 VI. RATIONALE FOR DISCHARGE PROHIBITIONS.............................................................234 A. Non-Stormwater Discharge Prohibitions ...................................................................234 B. Trash Discharge Prohibition......................................................................................238 VII.RATIONALE FOR TRASH CONTROL PROVISIONS .......................................................238 VIII. RATIONALE FOR RECEIVING WATER LIMITATIONS ...............................................239 IX. RATIONALE FOR EFFLUENT LIMITATIONS AND DISCHARGE SPECIFICATIONS ......241 A. Technology-Based Effluent Limitations (TBELs).......................................................241

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B. Water Quality-Based Effluent Limitations..................................................................243 X. RATIONALE FOR NEW DEVELOPMENT (INCLUDING SIGNIFICANT REDEVELOPMENT) PROVISIONS....................................................................................................................252 A. Hierarchy for Treatment Control Measures ...............................................................255 B. Integration of Project WQMPs into the Development Application Process ................257 C. Non-Priority Projects.................................................................................................259 D. Treatment Control Measures Related to New Development and Significant Redevelopment Versus Other Treatment Control Measures.....................................259 E. Regional and Subregional Treatment Control Measures...........................................260 F. Alternatives and In Lieu Programs ............................................................................260 G. Credit trading............................................................................................................261 XI. RATIONALE FOR ILLICIT DISCHARGE DETECTION AND ELIMINATION PROGRAM ..262 XII.RATIONALE FOR PUBLIC EDUCATION AND OUTREACH PROVISIONS......................263 XIII. RATIONALE FOR TRAINING PROGRAMS.................................................................264 XIV. RATIONALE FOR WATERSHED MANAGEMENT PLANS..........................................265 A. Purpose of Watershed Management Plans...............................................................265 B. Watershed Management Plan Development and Contents.......................................267 C. Implementation and Termination of a Watershed Management Plan ........................268 XV.RATIONALE FOR MUNICIPAL INSPECTIONS OF CONSTRUCTION, INDUSTRIAL, AND COMMERCIAL SITES.......................................................................................................270 XVI. RATIONALE FOR MUNICIPAL FACILITIES/ACTIVITIES PROVISIONS .....................270 XVII. RATIONALE FOR PROGRAM EFFECTIVENESS ASSESSMENTS PROVISIONS.....271 XVIII. RATIONALE FOR MONITORING AND REPORTING PROGRAM...............................273 XIX. RATIONALE FOR STANDARD PROVISIONS.............................................................274 XX.RATIONALE FOR REOPENER AND PERMIT MODIFICATION.......................................274 XXI. WATER CODE SECTION 13241..................................................................................274 A. Past, Present, and Probable Future Beneficial Uses of Water ..................................277 B. Environmental Characteristics of the Hydrographic Unit Under Consideration, Including the Quality of Water Available Thereto......................................................................277 C. Water Quality Conditions that Could Reasonably be Achieved Through the Coordinated Control of All Factors Which Affect Water Quality in the Area...............277 D. Economic Considerations .........................................................................................279 E. The Need for Developing Housing Within the Region ...............................................289 F. The Need to Develop and Use Recycled Water........................................................290 XXII. STATE MANDATES.....................................................................................................291 A. Permittees Have Authority to Fund Permit Compliance Costs Through Service Charges, Fees, or Assessments...............................................................................291 B. New or Modified Permit Requirements Do Not Mandate New Programs or Higher Levels of Service. .....................................................................................................292 C. The Permit Requirements Are Non-Reimbursable Federal Mandates.......................294 XXIII. PUBLIC PARTICPATION AND NOTIFICATION...........................................................297 A. Overview of Regional MS4 Permit Outreach Efforts..................................................297

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B. Outreach and AB 2108 .............................................................................................298 C. Written Comment Period and Public Hearing............................................................301

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I. PURPOSE
As described in section II.D.2 of Order R8-2024-0001 (Order), the Santa Ana Water Board incorporates this Fact Sheet as findings of the Santa Ana Water Board supporting the issuance of the Order. The purpose of this Fact Sheet is to describe the principal facts, the methodology, and the significant legal and policy matters considered by Santa Ana Water Board in preparing the Order. This Fact Sheet also serves as a technical report and contains the information described in 40 CFR sections 124.8 and 124.56.

CONTACT INFORMATION
The Order and other related documents are available at the Santa Ana Water Board’s website at:
http://www.waterboards.ca.gov/santaana/water_issues/programs/stormwater/ The documents referenced in this Fact Sheet and in the Order are also available for public review at the Santa Ana Water Board office at the address below. These and other public records are available for inspection during regular business hours from 8:00 am to 5:00 pm Monday through Friday, except for State Holidays. The Santa Ana Water Board office address is:
3737 Main Street, Suite 500
Riverside CA 92501-3348
Persons interested in reviewing or obtaining copies of public records are encouraged to do so by appointment. An appointment can be made by e-mail, facsimile, telephone, or in person. Requests by mail should be made to the attention of “File Review Request” at the Santa Ana Water Board office address shown above. Contact information for other means of communication is as follows:

Phone: (951) 782-4130
Facsimile:(951) 781-6288
E-mail: [email protected]
Appointments are not mandatory, but they will help Santa Ana Water Board staff fulfill requests efficiently and prevent delays while records are being located, retrieved, and reviewed, if necessary.

The Order includes numerous references to webpages to save paper and simplify the presentation of the permit and related documents. In an electronic format, the permit and related documents may contain live links to websites. These links and website addresses may become broken or outdated during the term of the Order. Consequently, these references have been provided for the convenience of the reader. Santa Ana Water Board staff will make every effort to update broken or outdated internet references in electronic versions of this Order posted at the Santa Ana Water Board’s website. Readers who become aware of broken or outdated reference or links are asked to contact Santa Ana Water Board staff in the Contact Information (section II) above to assist in this effort.

The following Santa Ana Water Board staff were involved in the development of the Order:

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Ray Akhtarshad, Principal Author
Water Resource Control Engineer
[email protected]
(951) 320-2024
Adam Fischer
Senior Environmental Scientist
Inland Section Chief
[email protected]
(951) 320-6363
Hero Alexander
Water Resource Control Engineer
[email protected]
(951) 782-4419
II. PERMIT INFORMATION
A. Permittees
Consistent with the designation agreements outlined in section II.B below, Table 1 presents the list of permitted entities whose discharges of pollutants in runoff to waters of the US are authorized by this Order. The entities identified in Table 1 are collectively referred to as Permittees, which include the Principal Permittees. All Permittees are owners and/or operators of municipal separate storm sewer systems (MS4s).

Table D.1: Permittees
Orange County
Principal Permittee County of Orange
Orange County
Permittees
Orange County Flood Control
District
City of Anaheim City of Los Alamitos
City of Brea City of Newport Beach
City of Buena Park City of Orange
City of Costa Mesa City of Placentia
City of Cypress City of Santa Ana
City of Fountain Valley City of Seal Beach
City of Fullerton City of Stanton
City of Garden Grove City of Tustin
City of Huntington Beach City of Villa Park

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City of Irvine City of Westminster
City of La Habra City of Yorba Linda
City of La Palma
Riverside County
Principal Permittee Riverside County Flood Control and Water Conservation District Riverside County
Permittees
County of Riverside City of Lake Elsinore
City of Beaumont City of Menifee
City of Calimesa City of Moreno Valley
City of Canyon Lake City of Norco
City of Corona City of Perris
City of Eastvale City of Riverside
City of Hemet City of San Jacinto
City of Jurupa Valley
San Bernardino County
Principal Permittee San Bernardino County Flood Control District San Bernardino County
Permittees
San Bernardino County City of Montclair
City of Big Bear Lake City of Ontario
City of Chino City of Rancho Cucamonga
City of Chino Hills City of Redlands
City of Colton City of Rialto
City of Fontana City of San Bernardino
City of Grand Terrace City of Upland
City of Highland City of Yucaipa
City of Loma Linda
Prior to issuance of this Order, the Santa Ana Water Board administered three separate MS4 Permits issued to permittees in the counties of Orange (R8-2009-0030), Riverside (R8-2010-0033), and San Bernardino (R8-2010-0036). These three MS4 Permits expired

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prior to the issuance of this Order but were administratively extended pursuant to 40 CFR section 122.6(d).

In accordance with the previous term MS4 Permits for Orange, Riverside, and San Bernardino counties, Reports of Waste Discharge (ROWD) were submitted by each county on behalf of their incorporated cities on October 3, 2013, July 29, 2014, and August 1, 2014, respectively.

B. Permittee Designation of Board
Regional Water Board boundaries are largely defined by watershed boundaries that may cross political or jurisdictional boundaries. Water Code section 13228 authorizes the Executive Officer of a Regional Water Board to grant a written request, made by an entity that is subject to regulation by more than one Regional Water Board, that one Regional Water Board be designated to regulate the matter. Several cities in Orange County, Riverside County, and Los Angeles County have requested such designation for regulation of pollutants in runoff from their MS4s.

In Orange County, written requests for designation were received during the last permit term from the cities of Laguna Hills (March 12, 2014), Laguna Woods (September 8, 2014), and Lake Forest (April 4, 2014). The cities of Laguna Hills and Laguna Woods requested designation to the San Diego Regional Water Quality Control Board for regulation of pollutants in runoff from their MS4s. The City of Lake Forest requested designation to the Santa Ana Water Board. The Santa Ana and San Diego Water Boards entered into an agreement consistent with these requests on February 10, 2015, contingent on the Santa Ana Water Board issuing draft Order R8-2015-0001, NPDES No. CAS618030, as amended or reissued. These requests for designation were recently renewed by the cities of Laguna Hills (August 4, 2022), Laguna Woods (July 11, 2022), and Lake Forest (December 15, 2022). Therefore, discharges from the Cities of Laguna Woods’ and Laguna Hills’ MS4s will be regulated through the San Diego Water Board’s regional MS4 permit. Under the San Diego Water Board’s regional MS4 permit, those cities must comply with all applicable requirements of Santa Ana Water Board TMDLs.

This includes meeting WQBELs, receiving water limitations and/or BMP requirements implementing the TMDLs’ WLAs for urban (MS4) discharges. The City of Lake Forest will continue to be covered as a permittee under this Order for discharges within the Santa Ana Region and under the San Diego Water Board’s regional MS4 permit for discharges within the San Diego Region.

In Riverside County, written requests for designation were received last permit term from the cities of Menifee (June 25, 2015), Murrieta (June 22, 2015) and Wildomar (June 23, 2015). The cities of Murrieta and Wildomar requested designation to the San Diego Regional Water Quality Control Board for regulation of pollutants in runoff from their MS4s. The City of Menifee requested designation to the Santa Ana Water Board. The requests for designation were granted by the respective Executive Officers of the Santa Ana Water Board and San Diego Regional Water Quality Control Board in a designation agreement dated October 26, 2015, subject to the conditions in that agreement. The requests for designation were renewed by the cities of Menifee (July 12, 2022), Murrieta (July 25, 2022), and Wildomar (November 15, 2022). This Permit continues the previous designations from the last permit term.

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In Los Angeles County, written requests for designation were received from the cities of Claremont (September 19, 2012) and Pomona (September 20, 2012). The cities of Claremont and Pomona requested designation to the Santa Ana Water Board for regulation of discharges of bacteria in runoff to the Middle Santa Ana River Watershed.

This request for designation was granted by the respective Executive Officers of the Santa Ana Water Board and Los Angeles Regional Water Quality Control Board in a designation agreement dated May 31, 2013. The cities of Pomona and Claremont are not Permittees under this Order but are covered under a separate NPDES Permit issued by the Santa Ana Water Board (NPDES Permit No. R8-2013-0043).

The Santa Ana Water Board reserves the right to terminate or modify the designation agreements or take enforcement actions for violations of the applicable MS4 permit pursuant to Water Code section 13228(b).

C. Permitted Discharges
Stormwater and non-stormwater discharges consist of surface runoff generated from various land uses, which is conveyed via the MS4 and ultimately discharge to surface waters throughout the region. Discharges of stormwater and non-stormwater through the MS4s within the Santa Ana Region convey pollutants to surface waters. The discharge of pollutants from MS4s may cause or contribute to exceedances of applicable water quality standards in receiving waters. See the findings in section II.B.1 through II.B.4 of the Order for additional detail. This Permit authorizes the discharge of pollutants in runoff from MS4s that are owned or operated by the Permittees listed in Table 1 above, subject to the receiving water limitations and effluent limitations in this Order. This Permit does not authorize the discharge of non-stormwater other than discharges authorized under section IV of the Order.

Attachment B of the Order provides a map depicting each major Watershed Management Area (WMA) in the Santa Ana Region and the major receiving waters therein to which the MS4 discharges.

D. Permit Scope
In 1987, the Clean Water Act (CWA) was amended to include section 402(p), which established a framework for regulating municipal and industrial stormwater discharges under the National Pollutant Elimination Discharge System (NPDES). On November 16, 1990, the United States Environmental Protection Agency (USEPA) amended its NPDES permit regulations to include requirements for stormwater discharges. These regulations are codified in 40 CFR parts 122, 123, and 124. According to the regulations, discharges of pollutants in runoff from municipal separate storm sewer systems (MS4s) are required to be regulated under NPDES permits.

The Order regulates discharges of stormwater and non-stormwater from the Permittees’ MS4s. 40 CFR section 122.26(b)(8) defines an MS4 as “a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains): (i) [o]wned or operated by a State, city, town, borough, county, parish, district, association, or other public body (created by or pursuant to State law) having jurisdiction over disposal of sewage, industrial wastes, storm water, or other wastes, including special districts under State law such as a sewer district, flood control district or drainage district, or similar entity, or an Indian tribe

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or an authorized Indian tribal organization, or a designated and approved management agency under section 208 of the CWA that discharges to waters of the United States; (ii) [d]esigned or used for collecting or conveying storm water; (iii) [w]hich is not a combined sewer; and (iv) [w]hich is not part of a Publicly Owned Treatment Works (POTW) as defined at 40 CFR [section] 122.2.”
Stormwater discharges consist of those discharges that originate from precipitation events. Federal regulations define “storm water” as “storm water runoff, snow melt runoff, and surface runoff and drainage.” (40 CFR § 122.26(b)(13).) While “surface runoff and drainage” is not defined in federal law, USEPA’s preamble to its final stormwater regulations demonstrates that the term is related to precipitation events such as rain and/or snowmelt. (55 Fed. Reg. 47990, 47995-96 (Nov. 16, 1990).) Non-stormwater discharges consist of all discharges through an MS4 that do not originate from precipitation events. Non-stormwater discharges through an MS4 are prohibited unless authorized under a separate permit; authorized pursuant to sections 104(a) or 104(b) of CERCLA; composed of natural flows; the result of emergency firefighting activities; or otherwise identified as exempt or conditionally exempt in section IV of the Order.

A permit issued to more than one Permittee for MS4 discharges may contain separate stormwater management programs for particular Permittees or groups of Permittees. (40 CFR § 122.26(d)(2)(iv).) For example, the Trash Control Provisions in section V of the Order only apply to Permittees with regulatory authority over priority land uses, designated land uses, and/or equivalent alternate land uses.

E. Rationale for Regional Permit
The Santa Ana Water Board retains the discretion as the permitting authority to determine whether to issue permits for discharges from MS4s on a system-wide or jurisdiction-wide basis. CWA section 402(p)(3)(B)(i) and implementing regulations at 40 CFR section 122.26, subdivisions (a)(1)(v), (a)(3)(ii), and (a)(3)(iv) allow the permitting authority to issue permits for MS4 discharges on a system-wide or jurisdiction-wide basis taking into consideration a variety of factors. Such factors include the location of the discharge with respect to waters of the United States, the size of the discharge, the quantity and nature of the pollutants discharged to waters of the United States, and other relevant factors.

Federal regulations at 40 CFR section 122.26(a)(3)(ii) identify a variety of possible permitting structures, including one system-wide permit covering all MS4 discharges or distinct permits for appropriate categories of MS4 discharges including, but not limited to, all discharges owned or operated by the same municipality, located within the same jurisdiction, all discharges within a system that discharge to the same watershed, discharges within a MS4 that are similar in nature, or for individual discharges from MS4s.

Consistent with CWA 402(p)(3)(B)(i), the Santa Ana Water Board is issuing the Order for the entire Santa Ana Region. The issuance of a region-wide MS4 Permit is also consistent with USEPA’s January 7, 2003 memorandum to transmit the final “Watershed-Based NPDES Permitting Policy Statement,” as this reflects the agency’s support for developing and issuing NPDES permits on a watershed basis. The Santa Ana Water Board is also issuing the Order to implement the State Water Board’s guiding principles for MS4 permit development by all regional water boards, which is provided in Order WQ 2015-0075.

Specifically, the State Water Board stated: “Phase I MS4 permits should (1) continue to

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require compliance with water quality standards in accordance with our Order WQ 99-05; (2) allow compliance with TMDL requirements to constitute compliance with receiving water limitations; (3) provide for a compliance alternative that allows permittees to achieve compliance with receiving water limitations over a period of time as described above; (4) encourage watershed based approaches, address multiple contaminants, and incorporate TMDL requirements; (5) encourage the use of green infrastructure and the adoption of low impact development principles; (6) encourage the use of multi-benefit regional projects that capture, infiltrate, and reuse storm water; and (7) require rigor, accountability, and transparency in identification and prioritization of issues in the watershed, in proposal and implementation of control measures, in monitoring of water quality, and in adaptive management of the program.”
The application of these principles on a regionwide basis results in improved consistency and uniformity, where warranted, in Phase I MS4 permit requirements, while providing Permittees the flexibility to tailor their implementation through watershed management plans that take into consideration unique watershed, socio-economic, land use, and geographic characteristics. This holistic approach provides a framework for addressing all stressors within a management area rather than focusing on individual sources within a city or other smaller area. A regionwide permit also provides the Permittees with a shared set of objectives, encourages them to share resources towards a common set of goals, and reduces the likelihood that programs will work at cross-purposes.

During the adoption proceedings for the previous term MS4 permits issued to Riverside, Orange, and San Bernardino Counties, Santa Ana Water Board staff invested considerable time and resources drafting MS4 permits for each county that were substantially similar and consistent with statewide requirements. The issuance of a regionwide MS4 permit allows for more efficient use of limited Santa Ana Water Board resources and time.

Where there are performance metrics that differ for each county’s program, the regionwide MS4 permit assigns individual requirements for each county. As with prior permits, each Permittee is responsible for implementing the requirements of the regionwide MS4 permit within its jurisdiction. The regionwide MS4 permit does not require counties to form a joint powers authority or use other formal forms of cooperation; they may continue working autonomously if desired. However, Permittees are encouraged to participate in area-wide or regional efforts to develop consistent procedures and approaches where such participation would be more efficient. A regionwide permit generally provides the Permittees with a consistent set of shared objectives which facilitates further cooperative use of their resources.

III. FACILITY DESCRIPTION
A. Overview of the Hydrology of the Santa Ana Region
In very broad terms, the Santa Ana Region is a group of connected inland subbasins and open coastal subbasins drained by surface streams flowing generally southwestward to the Pacific Ocean. The outer boundaries of the region are mostly made up of the mountain peaks of the San Gabriel and San Bernardino Mountains to the north and the San Jacinto Mountains to the southeast. The inland subbasins are separated from the coastal subbasins by the Chino Hills and Santa Ana Mountains. The county line between Los

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Angeles and Orange County is the only political boundary that defines the Santa Ana Region.

The hydrology of the Santa Ana Region is highly variable and is influenced by urbanization and concerted water supply management efforts. The lower valleys experience average annual rainfall that ranges from approximately 10.6 inches in the Perris Valley area,15 inches in the Chino Basin area, and 11 inches along the coast 7 , 8 , 9 . In the higher
elevations, average annual precipitation is substantially higher, with up to 30 inches at the western edge of Big Bear Valley10
.

Precipitation is not sufficient to meet water demand in the Santa Ana Region. In the Orange County Water District, aerial recharge from precipitation/irrigation accounts for 66,000 acre-feet of the groundwater basins’ in-flow while total water demand for the 2013- 14 water year was 449,000 acre-feet11
. In the Inland Empire Utilities Agency’s service
area, local surface water and groundwater, a portion of which is infiltrated stormwater runoff, comprises approximately 45% of the annual average regional water supplies12.

The general strategy to meet water demand is indirect reuse of recycled water for potable uses and direct reuse of recycled water for non-potable uses such as irrigation. The Santa Ana Region has substantial groundwater basins that store recycled and imported water and infiltrated stormwater runoff. Various spreading grounds, infiltration basins, and other recharge facilities are operated by flood control districts and water suppliers. Many facilities in the San Bernardino Valley area, such as the Mill Creek Spreading Grounds have been in operation since the 1930s13.

Because of the variability in precipitation, recycled water is regarded as a more reliable resource than stormwater runoff. Recycled water is one of the most reliable supply types7.

Where available, recycled and imported water is infiltrated when a facility is not being used for flood control or stormwater infiltration. Hydraulic gradients are controlled at various groundwater basins to protect lower quality water from intruding into higher quality ground and surface water. Hydraulic gradient control is also used to contain groundwater contamination plumes. The previous orders prioritized the use of stormwater retention facilities for new development and significant redevelopment. This resulted in the installation of relatively small-scale stormwater recharge facilities, such as dry wells and retention basins on private property as early as 2011. These private facilities supplement local water resources, but their impact is not as easily quantified as the larger, more centralized facilities run by institutional operators. The previous orders also included conditions where a retention facility would not be used if it would conflict with the need for 7 Inland Empire Utilities Agency. 2020 Urban Water Management Plan, Kennedy Jenks, June 29, 2021 8 City of Newport Beach. Average Temperature & Rainfall, Average Temperature & Rainfall | City of Newport Beach (newportbeachca.gov), accessed October 29, 2021
9 Eastern Municipal Water District. Urban Water Management Plan 2020, July 1, 2021 10 United States Geologic Service. Geohydrology of the Big Bear Valley. Geohydrology of the Big Bear Valley (usgs.gov), accessed October 29, 2021
11 OCWD, 2015. OCWD Groundwater Management Plan 2015 Update, Orange County Water District, June 17, 2015
12 IEUA 2020. Inland Empire Utilities Agency Regional Drought Contingency Plan, IEUA, April 2020 13 Orange County Water District. A History of Orange County Water District. Available at:
https://www.ocwd.com/media/1606/a-history-of-orange-county-water-district.pdf. Accessed January 4, 2022

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hydraulic control to protect groundwater quality or with groundwater cleanup efforts. The Order continues those same requirements but also removes some barriers that discouraged regional facilities that would serve multiple projects. Consequently, the Order is better aligned with statewide efforts to increase water supplies.

Since the early 1900’s, urbanization has exposed urban areas to flood risks. Flood events, such as the one in 1938, prompted flood control improvement projects that were initially carried out by agricultural cooperatives13. Later projects were carried out by the US Army Corps of Engineers and flood control districts. These projects included constructing channels to drain wetlands, constraining, and straightening channels, and constructing dams and detention facilities. The urbanization of watersheds has led to an increase in the amount of impervious land. Impervious land produces substantially more runoff volumes to receiving waters, necessitating detention facilities and channel modifications that armor the bed and banks of streams and prevent flooding. The development of water resources for agriculture and, later, for urban landscape irrigation resulted in nuisance flow that altered habitats in receiving waters. The combined effects of these efforts have resulted in degradation of the physical and biological integrity of most urban waters. These efforts continue today and will be necessary to meet regional housing needs.

The previous orders included new limitations on discharges from new development and significant redevelopment that have the potential to degrade the physical integrity of the receiving waterbody. This impact is known as hydromodification. These limitations resulted in stormwater retention facilities that both removed pollutants in the discharge and controlled the runoff flows that may cause hydromodification. Mostly, these facilities are small-scale and privately owned. These facilities are not designed to meet flood control needs in the receiving waters, but they do help to incrementally reduce the highest design storm flow (100-year, 24-hour event). The cumulative hydraulic effect of these facilities in receiving waters is not easily quantified. This is because of their distributed nature and the uncertain reliability of their operators. The Order continues limitations to address hydromodification. Unless their effect is included in design calculations for flood control improvement projects, these facilities are unlikely to play a significant role in preserving the beneficial uses of waters that pose a flood risk for existing communities.

B. Description of Receiving Waters and Watershed Management Areas Stormwater and non-stormwater discharges from the MS4 enter receiving waters in the major Watershed Management Areas of Big Bear Area, Mountain Santa Ana River, Upper Santa Ana River, Middle Santa Ana River, Lower Santa Ana River, San Jacinto, Coyote Creek, Carbon Creek, Anaheim, Newport Bay, and Newport Coast. The locations of the different Watershed Management Areas are depicted in Attachment B of the Order.

The major surface waters that receive discharges of pollution from MS4s include the Santa Ana River, Big Bear Lake, the San Jacinto River, Canyon Lake, Lake Elsinore, Newport Bay, and the Pacific Ocean. All these waterbodies have received discharges of pollutants from MS4s and other point and non-point sources since at least 1968, although the relative contribution of the different pollutants from each source category has varied due to changes in land use.

Many trend analyses have been performed in the Santa Ana Region for different waterbodies and pollutants. These analyses were performed at different levels of detail

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regarding the pollutant sources, and some of these pollutants are ones for which TMDLs were developed. None of the analyses were found to cover a period that extends back to 1968, the baseline year for evaluating water quality for purposes of the State Antidegradation Policy (State Water Board Resolution No. 68-16).

Trend analyses performed for the Newport Bay watershed for nutrients, algal biomass, and fecal indicator bacteria show improved or consistent water quality14 . The USGS
performed trend analyses for pollutants in wastewater treatment plant effluent, atmospheric deposition, and manure and fertilizer application in the Santa Ana Basin between 1975 and 200415
. Nitrogen and phosphorous in manure generally remained steady until about 1997 before beginning a decline. Nitrogen in manure production decreased by 34 percent during 1982-2002 and phosphorous declined by 36 percent during 1987-200216
. Nitrogen and phosphorous in fertilizer also remained steady until about 1997 before beginning to slightly increase. From 1975 to 2004, total nitrogen loads from wastewater treatment plants increased by 14 percent and, from 1985 to 2004, decreased by 25 percent17
. Exceptions to this trend was found in the Santa Ana River near San Bernardino and near Mentone and Warm Creek near San Bernardino, where the flow-adjusted concentration trend was increasing for nitrate, total nitrogen, and phosphorous. From 1975 to 2004, total phosphorous loads from wastewater treatment plants decreased by 60 percent18.

An apparent downward trend has been reported for Escherichia coliform in Prado Park Lake and Mill-Cucamonga Creek between 2007 and 201519. Geometric mean densities of Escherichia coliform in the Middle Santa Ana River and Chino Creek appear steady during the same period20.

Average fecal coliform concentrations in Newport Bay have decreased substantially since 2001 and reductions in sediment, total phosphorous and total nitrogen have been observed since 199921. The percent of samples of dry weather flow in Orange County that contain detectable concentrations of organophosphate pesticides has generally decreased since 2006. For pesticides such as chlorphyrofos and fensulfothion, measured increases in the rate of detectable concentrations are likely attributed to improvements in 14 Schiff, K.C., A.E. Fetscher, M.M. Hanken. 2014. Newport Bay Watershed Monitoring Evaluation. Technical Report 815. Southern California Coastal Water Research Project. Costa Mesa, CA. 15 Kratzer, C.R. & Kent, Robert & Saleh, Dina & Knifong, D.L. & Dileanis, P.D. & Orlando, James. (2011). Trends in Nutrient Concentrations, Loads, and Yields in Streams in the Sacramento, San Joaquin, and Santa Ana Basins, California, 1975-2004. US Geological Survey, National Water-Quality Assessment Program. Sacramento, CA. 16 Ibid.
17 Ibid.
18 Ibid.
19 CDM Smith. 2021. Santa Ana River Regional Bacteria Monitoring Program Annual Report: 2020-2021. Prepared for the Santa Ana Water Project Authority. June 2021.
20 Ibid.
21 Orange County Unified Annual Progress Report, Santa Ana Region, 2020-2021 Reporting Period. November 15, 2021.

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the method detection limits22. Discharges of nitrate from San Diego Creek into Newport Bay have shown a decreasing trend since 200623.

The weighted average of total phosphorous concentrations in Big Bear Lake have more than doubled from approximately 40 µg/L in 2009 to almost 100 µg/L in 202024 .

Wet weather concentrations of turbidity, lead and copper in the Santa Ana River have decreased from 2010 and 2014; no statistically significant changes have been detected for phosphorous and total nitrogen25. At the Hemet Channel outfall, total nitrogen was found to be increasing over the same period. In the Perris Valley Channel, concentrations of total inorganic nitrogen, ammonia, nitrate, and orthophosphate were decreasing from 2010 and 201426
. In Salt Creek, San Jacinto River, and Canyon Lake spillway, bioavailable forms of nitrogen were found decreasing in wet weather over the same period. Total phosphorous and orthophosphorous concentrations in wet weather were increasing in Salt Creek and at the Canyon Lake spillway and a decreasing trend was observed for orthophosphorous in the San Jacinto River over the same period27 .

Permittees performed trend analyses for Sunnymead Channel, Hemet Channel, the Corona Storm Drain, Magnolia Center Storm Drain, University Wash, Norco Channel, Perris Line J, and Perris Valley Channel, spanning between 9 and 29 years. Generally, concentrations of copper, lead, selenium, and zinc demonstrated decreasing trends, while densities of fecal indicators and concentrations of total nitrogen, total organic nitrogen, total Kjeldahl nitrogen, ammonia and orthophosphorous show mostly increasing trends.

C. Description of the Permittees’ MS4s
The Permittees’ MS4s are based on regional floodwater management systems that use both natural and altered waterbodies to achieve flood management goals. Most Permittees’ MS4s comprise a large interconnected system used by multiple municipalities.

The system is generally made up of larger channels, pipes, and other conveyances that are owned or operated by flood control districts.

MS4s that are owned or operated by the other Permittees typically drain to flood control district facilities or directly to receiving waters. Private storm drain systems, operated by commercial facilities, gated communities, and other private entities, discharge to the Permittees’ MS4 through underground lateral pipes or through surface conveyances such as gutters. Many portions of MS4s consist of underground pipes that are located underneath transportation rights of way. These pipes may be relatively small round pipes or larger round, oval, or rectangular pipes ten or more feet in width. Generally, the underground drainage capacity is supplemented by the capacity of the roadway’s curb and gutter system. The combined underground and surface conveyance capacity is generally for a storm event with a 100-year return interval. Additional flood protection is 22 Ibid.
23 Orange County Unified Annual Progress Report, Santa Ana Region, 2018-2019 Reporting Period. November 15, 2019.
24 San Bernardino County Areawide Municipal Stormwater Program. 2020. Big Bear Lake - Nutrient TMDL Annual Water Quality Report 2019, February 15, 2020
25 Riverside County Report of Waste Discharge, July 29, 2014. 26 Ibid.
27 Ibid.

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provided by elevating adjacent structures above the top of the roadway’s curb. Older communities or areas with less developed drainage infrastructure may not have all these features. In most cases, older or less developed areas may have roadside ditches or gutters, but lack underground conveyances. This extensive system conveys commingled stormwater and non-stormwater from many land use types across municipal boundaries where it is then discharged to receiving waterbodies.

Non-stormwater discharges are the result of many routine and non-routine activities in the urban environment. Residential activities that may produce non-stormwater discharges include overirrigation of landscaping, private vehicle washing, chlorinated and saltwater pool drainage, illicit discharges from clothes washing machines, and sanitary sewer overflows from private sewer laterals or septic systems. Commercial activities that may produce non-stormwater discharges include overirrigation of landscaping; commercial vehicle washing; wastewater from washing equipment, waste areas (e.g. trash enclosures), and production areas; leaks from cooling and refrigeration equipment; and accidental releases. Non-stormwater discharges may also include water transfers between water purveyors through the MS4, rising groundwater, exfiltration of sewage into the storm drain from nearby sewer lines, and others. The MS4s will also convey pollutants deposited on surfaces in urban areas. These include pesticides; fertilizers; trash; leaf litter and clippings from ornamental landscaping; domestic animal waste; leaked or spilled automotive fluids; particles from automobile brake and tire wear, atmospherically deposited combustion byproducts and industrial processes; and other pollutants.

Stormwater and non-stormwater are conveyed through the MS4s and ultimately discharge into receiving waters of the Santa Ana Region. MS4s subject to the Order receive stormwater and non-stormwater flows from various sources, including conveyances owned by the Permittees covered by the Order and other public agencies, NPDES permitted discharges, discharges authorized by USEPA (including discharges subject to a decision document approved pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), rising ground water, and natural flows.

The Santa Ana Region comprises all basins draining into the Pacific Ocean between the southeasterly boundary of the Los Angeles region and a line which follows the drainage divide between Muddy and Moro Canyons from the ocean to the summit of San Joaquin Hills; thence along the divide between lands draining into Newport Bay and into Laguna Canyon to Niguel Road; thence along Niguel Road and Los Aliso Avenue to the divide between Newport Bay and Aliso Creek drainages; thence along that divide and the southeasterly boundary of the Santa Ana River drainage to the divide between Baldwin Lake and Mojave Desert drainages; thence along that divide to the divide between Pacific Ocean and Mojave Desert drainages. (Wat. Code, § 13200(e).) Maps depicting the major drainage infrastructure within the area covered under the Order are included in Attachment B. Rough estimates based on information from Permittees indicate that the Santa Ana Region has an over 2,000-mile network of MS4 infrastructure (including main storm drain lines, lateral lines, and culverts). This does not include roadways’ curb and gutters, roadside ditches, and similar surface drainage.

IV. APPLICABLE STATUTES, REGULATIONS, PLANS, AND POLICIES A. Municipal Separate Storm Sewer System Requirements

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Clean Water Act section 402(p) requires the USEPA, or authorized states, to issue NPDES permits for discharges of pollution in stormwater runoff from Municipal Separate Storm Sewer Systems (MS4s) to waters of the United States. Clean Water Act section 402(p)(3)(B) allows such NPDES permits to be issued on a system-wide or jurisdictionwide basis. Section 402(p)(3)(B)(ii) requires that these NPDES permits “effectively prohibit non-stormwater discharges” into the MS4s. Section 402(p)(3)(B)(iii) requires these NPDES permits to “require controls to reduce the discharge of pollutants to the maximum extent practicable (MEP), including management practices, control techniques and system, design and engineering methods, and such other provisions as the Administrator or the State determines appropriate for the control of such pollutants.” The Porter-Cologne Water Quality Control Act (Wat. Code, § 13000 et seq.) established the State Water Board and the nine Regional Water Quality Control Boards. The Water Boards are the principal state agencies with primary responsibility for the coordination and control of water quality in California. The Santa Ana Water Board has primary responsibility for the coordination and control of water quality in the Santa Ana Region.

The Water Boards implement the Clean Water Act through chapter 5.5 of the Water Code, commencing with section 13370. Section 13377, in part, gives the Water Boards the authority to issue waste discharge requirements (WDRs) to ensure compliance with all applicable provisions of the Clean Water Act.

The Order is issued pursuant to Clean Water Act section 402 and implementing regulations adopted by the USEPA, and pursuant to chapter 5.5, division 7 of the Water Code (commencing with section 13370).

B. Federal and California Endangered Species Acts
The Order does not authorize any act that results in the taking of a threatened or endangered species or any act that is now prohibited or becomes prohibited in the future under either the California Endangered Species Act (Fish & Game Code, §§ 2050-2116) or the federal Endangered Species Act (16 USC §§ 1531-1544). The requirements of the Order are designed maintain water quality and prevent a condition of pollution, contamination, or nuisance in waters of the United States. The Permittees are independently responsible for meeting all requirements of the federal and state Endangered Species Acts.

C. California Environmental Quality Act
The adoption of this NPDES Permit for the discharge of pollutants in runoff from MS4s to waters of the United States is exempt from the provisions of chapter 3 of the California Environmental Quality Act (CEQA) (Pub. Res. Code, § 21100 et seq.) pursuant to Water Code section 13389. (County of Los Angeles v. Cal. Water Boards (2006) 143 Cal. App. 4 th 985.)
D. Water Quality Control Plans
The Clean Water Act requires the Santa Ana Water Board to establish water quality standards for each waterbody in its region. The requirements of the Order are designed to attain and maintain water quality standards. Water quality standards are composed of

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beneficial uses, water quality objectives or criteria established at levels to protect those beneficial uses, and the State and federal antidegradation policies.

1. Water Quality Control Plan for the Santa Ana River Basin On January 24, 1995, the Santa Ana Water Board adopted the Water Quality Control Plan for the Santa Ana River Basin (Basin Plan). The Santa Ana Water Board has amended the Basin Plan on multiple occasions since 1995. The Basin Plan designates beneficial uses, establishes water quality objectives, and contains programs and policies to achieve those objectives for all waters in the Santa Ana Region. The requirements of the Order implement the Basin Plan.

The Basin Plan identifies the following existing and potential beneficial uses for surface waters in the Santa Ana Region, which receive discharges from the Permittees’ MS4s: Municipal and Domestic Supply (MUN); Agricultural Supply (AGR); Industrial Process Supply (PROC); Industrial Service Supply (IND); Ground Water Recharge (GWR); Navigation (NAV); Hydropower Generation (POW); Water Contact Recreation (REC1); Non-contact Recreation (REC2); Commercial and Sport Fishing (COMM); Warm Freshwater Habitat (WARM); Limited Warm Freshwater Habitats (LWRM); Cold Freshwater Habitat (COLD); Preservation of Biological Habitats of Special Significance (BIOL); Wildlife Habitat (WILD); Rare, Threatened, or Endangered Species (RARE); Spawning, Reproduction, and Development (SPWN); Marine Habitat (MAR); Shellfish Harvesting (SHELL); and Estuarine Habitat (EST).

2. Water Quality Control Plan for Ocean Waters of California The State Water Board adopted the Water Quality Control Plan for Ocean Waters of California (Ocean Plan) in 1972. The Ocean Plan has been amended several times, including in 1978, 1983, 1988, 1990, 1997, 2000, 2005, 2009, 2012, 2015, 2017 and 2018. The Ocean Plan is applicable, in its entirety, to point source discharges to the ocean.

The Ocean Plan identifies the following beneficial uses of ocean waters of the State to be protected: industrial water supply; water contact and non-contact recreation, including aesthetic enjoyment; navigation; commercial and sport fishing; mariculture; preservation and enhancement of designated Areas of Special Biological Significance; rare and endangered species; marine habitat; fish spawning and shellfish harvesting.

The Ocean Plan prohibits the discharge of waste to designated Areas of Special Biological Significance (ASBS) unless an exception to Ocean Plan requirements is issued by the State Water Board. On March 20, 2012, the State Water Board approved Resolution No. 2012-0012, which includes exceptions to the Ocean Plan prohibition for specific discharges to various ASBS for certain nonpoint source discharges and NPDES-permitted municipal stormwater discharges. Resolution No. 2012-0012 requires monitoring and testing of marine aquatic life and water quality in several ASBS to protect California’s coastline during storms when rainwater overflows into coastal waters. Specific terms, prohibitions, and special conditions were adopted to provide special protections for marine aquatic life and natural water quality in ASBS. Resolution No. 2012-0012 includes exceptions for discharges from the City of Newport Beach MS4 to Newport Coast and Crystal Cove and from The

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Irvine Company, the California Department of Parks and Recreation and the California Department of Transportation to Crystal Cove. The Special Protections contained in Attachment B of Resolution No. 2012-0012, as applied to discharges to ASBS, are incorporated into the Order.

In recent years, the State Water Boad has adopted several important amendments to the Ocean Plan. Effective January 12, 2016, the Ocean Plan was amended with trash provisions, which established among other things a narrative water quality objective for trash and a prohibition on the discharge of trash along with implementation and monitoring requirements. This amendment was through the adoption of Resolution No. 2015-0019. The State Water Board also adopted an amendment to the Ocean Plan on August 7, 2018 to incorporate bacteria provisions and a water quality standards variance policy.

3. Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries (ISWEBE)
The State Water Board has adopted various provisions, which make up, collectively, the Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries (ISWEBE) of California.

On September 16, 2008, the State Water Board adopted the Water Quality Control Plan for Enclosed Bays and Estuaries – Sediment Quality Provisions (Sediment Quality Provisions). The Sediment Quality Provisions became effective on August 25, 2009. The Sediment Quality Provisions establish: 1) narrative sediment quality objectives to protect benthic communities from exposure to contaminants in sediment and to protect human health; and 2) a program of implementation using a ‘multiple lines of evidence’ approach to interpret the narrative sediment quality objectives. The requirements of this Order implement the Sediment Quality Provisions. Amendments to the Sediment Quality Provisions were adopted on June 5, 2018 by Resolution No. 2018-0028.

On April 7, 2015, the ISWEBE Plan was amended with Part 1: Trash Provisions. This amendment was through the adoption of Resolution No. 2015-0019, which became effective on January 12, 2016.

On May 2, 2017, the ISWEBE Plan was amended with Part 2: Tribal Subsistence Beneficial Uses and Mercury Provisions. This amendment was adopted through Resolution No. 2017-0027, which became effective on June 28, 2017.

On August 7, 2018, the ISWEBE Plan was amended with Part 3: Bacteria Provisions and Variance Policy. This amendment was through the adoption of Resolution No. 2018-0038, which became effective on February 4, 2019.

On April 2, 2019, the ISWEBE Plan was amended by Resolution No. 2019-0015, State Policy for Water Quality Control: State Wetland Definition and Procedures for Discharges of Dredged or Fill Material to Waters of the State. The amendment became effective on May 28, 2020.

E. National Toxics Rule (NTR) and California Toxics Rule

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USEPA adopted the National Toxics Rule (NTR) on December 22, 1992, and later amended it on May 4, 1995, and November 9, 1999. About forty criteria in the NTR applied in California. On May 18, 2000, USEPA adopted 40 CFR section 131.38 (Water Quality Standards; Establishment of Numeric Criteria for Priority Toxic Pollutants for the State of California), also known as the California Toxics Rule (CTR). The CTR promulgated new toxics criteria for California and incorporated the previously adopted NTR criteria that were applicable in the state. The CTR was amended by USEPA on February 13, 2001. The CTR and NTR contain water quality criteria for priority pollutants in surface water. The requirements of the Order are consistent with the NTR (40 CFR section 131.36) and CTR (40 CFR section 131.38).

The State Policy for Implementation of Toxics Standards for Inland Surface Waters, Enclosed Bays, and Estuaries of California, also known as the State Implementation Policy (SIP), implements the CTR. However, the SIP states that the policy does not apply to regulation of stormwater discharges.

F. Clean Water Act Section 303(d) List
Clean Water Act section 303(d)(1) requires each state to identify specific waterbodies within its boundaries where water quality standards are not being met or are not expected to be met after technology-based effluent limitations on point sources of pollutants have been complied with. Waterbodies that do not meet water quality standards are considered impaired and are placed on the state’s “303(d) List”. For each listed waterbody, the state or USEPA is required to establish a Total Maximum Daily Load (TMDL) for each pollutant that is impairing the water quality standards in that waterbody.

A TMDL is the sum of the allowable pollutant loads of a single pollutant from all contributing point sources (waste load allocations), non-point sources (load allocations), the contribution from background sources, and a margin of safety. (40 CFR § 130.2(i).) MS4 discharges are considered point source discharges and are assigned waste load allocations (WLAs). A TMDL is a tool for implementing water quality standards and is based on the relationship between pollution sources and receiving water quality. The TMDL establishes the allowable pollutant loads from various sources to a waterbody and thereby provides the basis to establish water quality-based controls or effluent limitations.

By implementing the water quality-based effluent limitations (WQBELs) in Appendices 2 through 13, the Permittees should provide the pollutant load reduction needed for a waterbody to meet water quality standards.

On April 6, 2018, the USEPA approved the State of California’s 2016 303(d) List of impaired waterbodies. The 2016 303(d) List includes certain receiving waters in the Santa Ana Region. Since 1998, USEPA and the Santa Ana Water Board have established TMDLs to address water quality impairments. These TMDLs establish waste load allocations (WLAs) for discharges from MS4s, and the Order includes WQBELs and other provisions to implement the TMDL WLAs for discharges from MS4s.

G. Antidegradation Policy
Federal regulations at 40 CFR section 131.12 require that state water quality standards include an antidegradation policy. The State Water Board established California’s antidegradation policy in State Water Board Resolution No. 68-16, “Statement of Policy with Respect to Maintaining High Quality of Waters in California”. Where the federal

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antidegradation policy is applicable, the State Water Board has interpreted Resolution No. 68-16 to incorporate the federal antidegradation policy28. The Santa Ana Water Board’s Basin Plan incorporates by reference both the State and federal antidegradation policies.

Resolution No. 68-16 and 40 CFR section 131.12 require that high quality waters be maintained unless degradation is justified based on specific findings. At a minimum, any degradation may not lower the quality of the water below water quality standards. The Santa Ana Water Board finds that the permitted discharges authorized by this Order are consistent with the antidegradation provisions of 40 CFR section 131.12 and State Water Board Resolution No. 68-16, as set forth below.

Federal regulations at 40 CFR section 131.12(a)(1) require that the Santa Ana Water Board ensure “existing instream uses and the level of water quality necessary to protect the existing uses” are maintained and protected. Administrative Procedures Update 90- 004 (APU 90-004) interprets this provision to mean that, “[i]f baseline water quality is equal to or less than the quality as defined by the water quality objective, water quality shall be maintained or improved to a level that achieves the objectives.” If the baseline quality of a waterbody for a given constituent “exceeds levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water”, then 40 CFR section 131.12(a)(2) provides that quality shall be maintained and protected unless the Santa Ana Water Board:
(1) finds that any lowering of the water quality is “necessary to accommodate important economic or social development in the area in which the waters are located”; (2) assures “water quality adequate to protect existing uses fully”; and (3) assures that “the highest statutory and regulatory requirements for all new and existing point sources and all cost-effective and reasonable best management practices for nonpoint source control” are achieved.

The Santa Ana Water Board must conduct an analysis of alternatives that evaluates practicable alternatives that would prevent or lessen the degradation associated with the discharges permitted. In the context of 40 CFR section 131.12(a)(2)(ii), practicable means “technologically possible, able to be put into practice, and economically viable” according to 40 CFR section 131.3(n).

Resolution No. 68-16 generally prohibits the Santa Ana Water Board from authorizing discharges that will result in the degradation of high quality waters, unless it is demonstrated that any change in water quality will (a) be consistent with maximum benefit to the people of the State, (b) not unreasonably affect beneficial uses, and (c) not result in water quality less than that prescribed in State and regional policies (e.g., the violation of one or more water quality objectives). Further, any activities that result in discharges to such high quality waters are required to use the best practicable treatment or control (BPTC) of the discharge necessary to avoid a pollution or nuisance and to maintain the highest water quality consistent with the maximum benefit to the people of the State. 28 State Water Board Order WQ 2015-0075, p. 23, citing WQ 86-17 (Fay).

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Resolution No. 68-16 does not define “best practicable treatment or control”; however, the State Water Board has evaluated what level of treatment or control is technically achievable using best efforts. (See State Water Board Orders WQ 81-5 (City of Lompoc), WQ 82-5 (Chino Basin Municipal Water District), WQ 90-6 (Environmental Resources Protection Council).) To evaluate the best practicable treatment or control method, the discharger should compare the proposed method to existing proven technology; evaluate performance data; compare alternative methods of treatment or control; and/or consider the method currently used by the discharger or similarly situated dischargers. The costs of the treatment or control should also be considered. (Questions and Answers, Resolution No. 68-16, State Water Board (Feb. 16, 1995), pp. 5-6.) High quality waters are surface waters or areas of groundwater that have a baseline water quality better than required by water quality control plans and policies. The baseline for this determination is generally 1968, the date of adoption of Resolution 68-16.

Alternatively, a lower level may be applied if that lower level was allowed through a permitting or other regulatory action, such as establishing a water quality objective, which was consistent with the federal and State antidegradation policies.

The Board Is Not Required to Make Waterbody by Waterbody and Pollutant by Pollutant Antidegradation Findings:

The Santa Ana Water Board is not required to conduct a waterbody by waterbody and pollutant by pollutant antidegradation analysis for this Order. The wide geographic area covered by the Order makes a waterbody by waterbody and pollutant by pollutant determination of the quality as of the baseline of 1968 impractical, and a “complete” antidegradation analysis is not required under the Administrative Procedures Update, Antidegradation Policy Implementation for NPDES Permitting, 90-004 (APU 90-004).

APU 90-004 is a guidance document establishing methods for implementing the federal and State antidegradation policies in NPDES Permits. APU 90-004 suggests that an antidegradation analysis requires a pollutant by pollutant and waterbody by waterbody analysis in certain contexts, specifically where the discharge at issue is a discrete discharge from a singular facility. However, the State Water Board has explained that APU 90-004 has limited value when considering antidegradation in the context of MS4 discharges from diffuse sources, conveyed through multiple outfalls, with multiple pollutants impacting multiple waterbodies over a wide geographic area. (Order WQ 2015- 0075, p. 27; see also WQ 2018-0002, p. 77 [reaching the same conclusion for agricultural discharges].) This reasoning was recently affirmed in the context of agricultural discharges by Environmental Law Foundation v. State Water Resources Control Bd. (2023) 89 Cal.App.5th 451, 499-500, in which the court upheld the State Water Board’s finding that the Regional Water Board needed only to “conduct [a] general assessment of the existing water quality data that is reasonably available” rather than undertake the “impossible” task of “establish[ing] an accurate numeric baseline for potentially hundreds of waterbodies and dozens of waste constituents in an area covered by a general order.” This interpretation of APU 90-004 is sensible for this Order for several reasons. First, an assessment of every waterbody-pollutant combination would not be reasonable.

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Excluding many tributaries, the Santa Ana Water Board’s Basin Plan identifies approximately 253 discrete surface waterbodies and stream segments. There are 53 numeric and narrative water quality objectives that apply to categories of these waters.

There are approximately 8,775 combinations of waterbodies and applicable water quality objectives. This excludes water quality objectives in statewide water quality control plans.

If assessments were performed for every waterbody-pollutant combination, qualitative assessments would be performed for narrative objectives. Quantitative assessments would be performed where adequate data was available. Where adequate data is unavailable, assessments would be based on a combination of qualitative and semiquantitative analyses. Many of the waterbodies do not receive discharges from urban sources. Even excluding these waters would leave hundreds to thousands of assessments that would need to be completed. It is unreasonable to believe that APU 90-004 envisions this approach.

Second, at the regional scale, the affected waterbodies and pollutants share common characteristics related to water quality condition, pollutants, and transport mechanisms.

There are few waterbody-pollutant combinations that are unique in these respects.

Further, there is no comprehensive set of water quality data that allows an evaluation of baseline water quality in 1968 for all waters that receive discharges from MS4s. This means that nearly all assessments would have to be based, in part, on qualitative assessments. In most cases, individual assessments of each waterbody-pollutant combination would result in conclusions that would be substantially identical. Considering the lack of detailed data and shared characteristics, categorized assessments of waterbody-pollutant combinations are appropriate for the purposes of this Order. An assessment of individual waterbody-pollutant combinations is unnecessary and would not be productive.

The Santa Ana Water Board additionally finds that APU 90-004 requires at most a “simple” antidegradation analysis. APU 90-004 contemplates that a “simple” antidegradation analysis is appropriate under specified circumstances. APU 90-004 states that a simple antidegradation analysis is allowed when a “Regional Board determines the reduction in water quality is temporally limited and will not result in any long-term deleterious effects on water quality” or where a “Regional Board determines the proposed action will produce minor effects which will not result in a significant reduction of water quality.” (APU 90-004, p. 2.)
29 Here, the Order continues the requirements of the previous orders and imposes equivalent or more protective requirements such that the water quality established under the prior orders is expected to be maintained and improved. Generally, the prior orders instituted controls such as a prohibition on non-stormwater discharges that are a source of pollutants through the MS4s, receiving water limitations, WQBELs based on TMDLs, and monitoring programs to help ensure that water quality will be maintained at the level it is now, or improve it. The Order institutes further controls such as additional TMDL-based WQBELs. 29 In an unpublished decision, the Second District Court of Appeal affirmed that a simple antidegradation analysis applied to the 2012 Los Angeles County MS4 permit. (Natural Resources Defense Council v. State Water Resources Control Board (2018) 2018 WL 6735201, at *6.)

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Any degradation permitted while controls are continuing to be developed will be temporally limited and will not result in any long-term deleterious effects on water quality. Such a finding would not be appropriate if, for example, the Order declined to require long-term compliance with water quality objectives, but that is not the case here.

The Santa Ana Water Board Makes the Following Antidegradation Findings:

The Santa Ana Water Board determines that the findings made below meet the requirements of a simple or general antidegradation analysis, as appropriate for the Order.

With these findings, based on the information available to it and using its best professional judgment, the Santa Ana Water Board concludes that the discharges permitted in the Order are consistent with the antidegradation provisions of 40 CFR section 131.12 and Resolution No. 68-16. The Santa Ana Water Board’s conclusion that the terms and conditions of the Order are consistent with the federal and State antidegradation policies is based on the following analysis.

1. Waterbodies that do not meet water quality objectives (waterbodies that are not high quality):

Most of the receiving waters within the area covered by the Order are not meeting water quality objectives for at least one pollutant associated with MS4s, meaning that they are not attaining water quality objectives necessary to protect beneficial uses. This is evidenced by the fact that all waterbodies in the region that receive discharges from MS4s are impaired for at least one waterbody-pollutant combination according to Clean Water Act section 303(d) or are tributary to impaired waterbodies. Either the Santa Ana Water Board or the USEPA has established numerous TMDLs to address many of these impairments. The source assessments for these TMDLs identify MS4 discharges as a source of the impairments.

Under both federal and State antidegradation policies, receiving waters with TMDLs are not “high quality” waters for the regulated pollutants. Given historical land use patterns and related polluting activities in the Santa Ana Region since 1968, it is reasonable to assume that waterbodies that do not meet water quality objectives now, due entirely or partly to urban sources, likely did not meet those water quality objectives in the baseline year of 1968. Although the contribution of urban sources relative to other sources has changed since 1968, urban sources have been present and only intensified since then.

For purposes of this analysis, these waters are not considered high quality waters.

For receiving waters that are not high quality waters, the federal antidegradation policy requires that regulatory actions ensure that existing instream uses and the level of water quality necessary to protect the existing uses is maintained and protected. (40 CFR § 131.12(a)(1).) The Order ensures that existing instream (beneficial) uses and the level of water quality necessary to protect the existing uses is maintained and protected through receiving water limitations. Receiving water limitations do not allow permittees to cause or contribute to exceedances of water quality objectives in the receiving waters. Existing instream beneficial uses and the necessary water quality are also protected by WQBELs implementing waste load allocations designed to restore impaired waterbodies with TMDLs. The Order also ensures that discharges will not unreasonably affect present and

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anticipated beneficial uses and will not result in water quality less than water quality objectives, as required by Resolution No. 68-16. This is achieved through the following provisions:
a. The Order requires compliance with receiving water limitations to meet water quality standards in the receiving waters by demonstrating compliance pursuant to section VI of the Order or implementing an approved Watershed Management Plan (WMP) pursuant to section XII of the Order. WMPs must specify treatment and source control measures that are demonstrated to have a reasonable assurance of achieving compliance with receiving water limitations and must be implemented according to a compliance schedule approved by the Executive Officer. The reasonable assurance analysis (RAA) must show that the system of pollution controls proposed in the WMP will achieve applicable WQBELs according to regulatory deadlines and that discharges will not cause or contribute to exceedances of receiving water limitations. The analysis used in the RAA must have its predictive performance quantified and validated using generally accepted methods, including models that have been subject to public and peer review. The purpose of the RAA is to provide transparency and a full evaluation of the likelihood of selected control measures to successfully achieve receiving water limitations and/or final WQBELs. The WMP must also include a qualitative assessment of non-technical risks such as funding, constructability of treatment control measures, community acceptance, and others. Additionally, the Order requires a comprehensive evaluation and update, through the required adaptive management process, of the WMP during the permit term to ensure progress toward achieving WQBELs and receiving water limitations.
b. The Order requires Permittees to comply with WQBELs and/or receiving water limitations consistent with the assumptions and requirements of WLAs assigned to MS4 discharges established in 12 TMDLs applicable to waterbodies in the Santa Ana Region. The TMDLs are intended to restore water quality to protect the beneficial uses of the impaired waterbodies.
c. The Order requires Permittees to implement a portfolio of projects and programs or system of controls, which includes major program elements or Minimum Control Measures (MCMs) in 40 CFR section 122.26(d)(2)(iv), and to effectively prohibit nonstormwater discharges that are a source of pollutants through the MS4 to receiving waters.
d. The Order includes requirements for extensive monitoring and reporting designed to identify changes in water quality at representative outfalls and in receiving waters. e. This Order requires the execution of a regimented or step-by-step iterative process for the continual improvement of projects and programs, Watershed Management Plans, and the Monitoring and Reporting Program during the permit term to achieve compliance with the WQBELs and receiving water limitations. Continual improvement is an ongoing effort to make changes to individual or system of control measures or best management practices. The regimented iterative process is driven by a set of permit provisions in section III.A. of the Order that require the Permittees to establish

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objective performance metrics that provide feedback on the performance of their control measures and BMPs and make improvements. A Watershed Management Plan, coupled with a regimented iterative process for continual improvement, serves as a method for Permittees to identify an optimal suite of best management practices that constitute best practicable treatment or control of the discharge. Execution of a regimented iterative process does not excuse or substitute for compliance with final compliance deadlines to meet TMDL WLAs.

These provisions are collectively designed to halt any further degradation of impaired waterbodies and improve the quality of such waters to a level that is protective of existing uses over a time schedule that is as short as possible. The antidegradation policies do not explicitly or implicitly override the authority and discretion granted to the Santa Ana Water Board by the Clean Water Act and the Water Code as to how it structures a permit to ensure water quality necessary to protect beneficial uses. The law does not require immediate restoration of impaired waterbodies, nor does it require an immediate prohibition of discharges that contribute to an exceedance in the waterbody. Rather, federal regulations at 40 CFR section 122.47 allow NPDES permits, including MS4 permits, to have compliance schedules.

Similarly, Water Code section 13263(c) authorizes the Santa Ana Water Board to include a time schedule for achieving water quality objectives in waste discharge requirements.

Where a TMDL has been established, Water Code section 13242 states that the TMDL implementation plan, as incorporated into the water quality control plan, shall include a time schedule for actions to be taken. When issuing waste discharge requirements, Water Code section 13263 requires Regional Water Boards to implement any relevant water quality control plans that have been adopted. Water quality objectives must be achieved; but the law recognizes and allows for the fact that it can take time to restore or achieve the objectives. While MS4 permits must include a technology-based standard of effectively prohibiting non-storm water discharges through the MS4 and reducing pollutants in the discharge to the maximum extent practicable, requiring strict compliance with water quality standards is at the discretion of the permitting agency30 .

In this regard, some impaired waterbodies may remain the same or continue to degrade before showing improvement. This period may be multiple years. This is not contrary to the authorities for compliance schedules stated above and is not contrary to the antidegradation policies. The antidegradation policies do not require socioeconomic findings justifying any continued degradation of waterbodies that are not high quality that may occur while the Permittees implement requirements according to a compliance schedule. If socioeconomic findings are required, the Santa Ana Water Board finds that this potential, limited, and temporary further lowering of water quality is justified for the same reasons articulated in section IV.G.2.b of this Fact Sheet, below.

2. High quality waterbodies:

The term “high quality waters” applies to waterbodies that may be high quality regarding some pollutants but not all. Some of the waterbodies within the area covered by the Order 30 33 U.S.C. § 1342(p)(3)(B); Defenders of Wildlife v. Browner (9th Cir. 1999) 191 F.3d 1159, 1166-67.

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may be high quality waters with regard to some pollutants. Some of these waterbodies may be currently high quality compared to current objectives. Others of these waterbodies may be currently impaired but may be classified as high quality waters because they were historically high quality for certain pollutants. Discharges of stormwater and nonstormwater from MS4s into such waterbodies may have lowered the quality of the waterbodies since 1968 for certain pollutants. For all these high quality waterbodies, the Santa Ana Water Board finds as follows:
a. Practicable Alternatives: The Santa Ana Water Board has evaluated a range of practicable alternatives that would prevent or lessen any degradation associated with permitted MS4 discharges to high quality waters. These alternatives are described below based on their major differences.
i. Alternative 1 – Complete prohibition on some or all pollutants in nonstormwater discharges to high quality waters: This alternative would prohibit MS4 discharges of some or all pollutants in non-stormwater to receiving waters.

By eliminating non-stormwater discharges, pollutants from non-stormwater discharges would not reach high quality receiving waters during dry weather and thus not cause any degradation. In high quality watersheds, this alternative could require the Permittees to either divert all non-stormwater to a facility for treatment, or retain all non-stormwater through retention basins, infiltration galleries, and other controls that would prevent non-stormwater from reaching surface waters.

Alternatively, Permittees could install specific pollutant control measures that prevent specific pollutants from being discharged through the MS4. ii. Alternative 2 – Complete prohibition on some or all pollutants in stormwater discharges to high quality waters: This alternative would prohibit MS4 discharges of some or all pollutants in stormwater to high quality receiving waters.

By eliminating these discharges, pollutants from stormwater would not reach high quality receiving waters during wet weather and not cause any degradation. As wet weather will always occur, this alternative could require the Permittees to either divert all stormwater in the MS4 to a facility for treatment, or retain through retention basins, infiltration galleries, and other controls. Permittees could also install pollutant control measures that prevent specific pollutants from being discharged through the MS4.
iii. Alternative 3 – Watershed Management Plan alternative compliance option without deemed compliance with receiving water limitations for any high quality waters: This alternative would allow the Permittees to implement approved WMPs with customized control measures to comply with receiving water limitations, attain WQBELs, and meet other requirements. Under this alternative, the Santa Ana Board would not deem a Permittee in compliance with receiving water limitations for high quality waters while they are fully implementing an approved WMP. This alternative includes a new, enforceable, regimented iterative process to continually improve the Permittees’ systems of controls.

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iv. Alternative 4 – Watershed Management Plan alternative compliance option with deemed compliance with receiving water limitations for high quality waters: This alternative would allow the Permittees to implement approved WMPs with customized control measures to comply with receiving water limitations, attain WQBELs, and meet other requirements in the same way as Alternative 3.

Alternative 4 would also include an enforceable regimented iterative process.

Unlike Alternative 3, the Santa Ana Board would conditionally deem a Permittee in compliance with receiving water limitations for current or historically high quality waters while they are developing and implementing an approved WMP. b. Economic and Social Development Considerations and Consistency with Maximum Benefit to the People of the State: The Santa Ana Water Board incorporated Alternative 4 and aspects of Alternatives 1 and 2 into the Order. These alternatives may allow limited degradation of high quality waterbodies by MS4 discharges, but these alternatives ultimately require MS4 discharges to meet and not fall below water quality standards. Such degradation of high quality waters 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 for the following reasons:
i. Alternatives 1 and 2, if implemented as full prohibitions, would hamper important social and economic development.
(a) Discharges of stormwater and non-stormwater to MS4s, in certain circumstances, are to the maximum benefit to the people of the State. The discharges may be necessary for flood control, public safety, and the availability of water supplies. MS4s include storm drainage facilities that are used to prevent flooding. Much of the flood control infrastructure is designed to mitigate the flood effects of urban development. The infrastructure is not always adequate to both control flooding and retain non-stormwater runoff and both functions are not compatible for all facilities. Storm drainage facilities may be used to facilitate water transfers between water purveyors and support domestic water supply. These temporary, non-stormwater discharges can mobilize pollutants, such as pathogens and nutrients, which may be present in the MS4. Requiring MS4 owners and operators to retain these discharges or to remove pollutants prior to discharge could interfere with a vital public service.

Complying with complete prohibitions in Alternatives 1 and 2 would not be practicable at all times and in all parts of the MS4.
(b) The majority of Permittees are cities and counties that provide essential and valuable public services. These services include police and emergency services, refuse collection, public transportation, nuisance abatement, parks and recreation, and the operation and maintenance of roads, drainage, and other infrastructure. In some cases, Permittees operate municipal airports and sewer and energy utilities. Funding sources for these services are varied and not always mutually interchangeable. For example, functional revenue from a municipal electric utility may not be diverted to fund unrelated pollution controls

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(Understanding the Basics of Municipal Revenues in California: Cities, Counties, and Special Districts, Institute for Local Government, 2016 Update).

Controlling stormwater discharges so there is no potential degradation of potential high quality waters through Alternatives 2 and 3 would require a rapid increase in appropriate revenue sources to fund various infrastructure and programs. A Permittee would have to make significant tradeoffs in the services that it provides its residents and businesses to comply with while funding is found. This may manifest itself in the reduction of some public services or prevent other public services from being provided. Reductions in service levels could harm the quality of life of residents and affect the efficiency of business’ economic activity. Reductions in service levels could disproportionately affect disadvantaged communities.
(c) The relationship between cost and levels of pollution reduction are typically non-linear. In many cases, the costs increase exponentially as dischargers employ more controls that achieve zero discharge of a pollutant.31 Assimilative capacity plays an important part in allowing some pollution without affecting beneficial uses by avoiding the exponentially increasing cost of achieving zero discharge. Such costs could be unnecessary if assimilative capacity is available so that the complete elimination of a pollutant in the discharge is not needed to protect beneficial uses. Efforts to comply with a complete prohibition are likely to experience diminishing returns. This is because costs typically increase exponentially relative to the benefits as permittees approach elimination of the pollutant load32
. In cases where the incremental pollutant
load falls within the receiving waterbody’s assimilative capacity, the related incremental cost of complying and eliminating that incremental load may have no benefit to the protection of beneficial uses. A complete prohibition may be a costly over-correction for some waterbody-pollutant combinations. (d) The effectiveness of Alternatives 2 and 3 should be considered in the context of the suite of regulatory actions to control pollutants from all contributors. A complete prohibition in this Order would conflict with other NPDES permits, such as State Water Board’s Construction General Permit and Industrial General Permits. There are also other NPDES permits that authorize the discharge of waste to high quality waters based, in part, on assimilative capacity. These discharges often commingle with runoff from MS4s and would complicate efforts to monitor compliance. A complete prohibition also conflicts with many of the region’s TMDLs, which assign waste load allocations that allow MS4 discharges of pollutants that have been calculated to achieve water quality objectives in the receiving waterbody.
(e) For some waterbody-pollutant combinations, such as nitrogen in Lake Elsinore and phosphorous in Big Bear Lake, the dominant causes of degradation are 31 (USEPA, 2010. Guidelines for Preparing Economic Analysis, Chapter 4, EPA 240-R-10-001, December 17, 2010, updated May 2014.)
32 (USEPA 2010. Guidelines for Preparing Economic Analysis, Chapter 4, EPA 240-R-10-001, December 17, 2010, updated May 2014).)

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pollutants that have accumulated from past discharges, legacy pollutants such as DDT in sediment, or non-point sources. In these cases, a complete prohibition of pollutants in runoff would not affect the dominant causes of degradation. A complete prohibition would not restore the high quality waterbody and could come at a high cost (and at the expense of other needed public services). For these waters, a complete prohibition may be unnecessary or socially inefficient because the most effective and least costly strategies, such as offsets or pollution trading among different sources in a watershed, were not considered. Dischargers would be preoccupied with eliminating their own discharges within the constraints of their own abilities instead of working to affect more cost-effective, collaborative strategies with one another in a watershed. Essentially, dischargers would narrowly frame the water quality problem, resulting in inefficient or ineffective solutions. ii. Certain aspects of Alternatives 1 and 2 are practicable and have been incorporated into the Order. As more fully described in sections VI.B and VII. of this Fact Sheet, the Order generally implements a prohibition on trash discharges through the installation of full capture systems or a system of controls to achieve full capture equivalency. These provisions are required by the State Water Board’s Amendment to the Water Quality Control Plan for Ocean Waters of California to Control Trash and Part 1 Trash Provisions of the Water Quality Control Plan for Inland Surface Waters, Enclosed Bays, and Estuaries of California (Trash Provisions), which became effective January 12, 2016. As more fully described in section VI.A of this Fact Sheet, the Order also largely prohibits the discharge of non-stormwater into the MS4 to receiving waters pursuant to Clean Water Act section 402(p)(3)(B)(ii). There are limited exceptions where the non-stormwater discharge is expected not to be a source of pollutants. The Order also prioritizes treatment control measures that maximize the capture of stormwater through retention basins, infiltration galleries, and other controls. iii. Alternatives 3 and 4 would implement the Order with the use of Watershed Management Plans (WMPs). Alternative 3 differs from Alternative 4 in that, while developing and implementing WMPs, Permittees would not be deemed in compliance with WQBELs and receiving water limitations for the waterbodypollutant combination(s) covered by the WMP. Both Alternatives 3 and 4, if implemented, could result in limited degradation of high quality waterbodies, particularly because WMPs allow the Permittees the flexibility to sequence tackling water quality priorities over time and on a watershed scale through customized strategies, control measures, and BMPs. However, the Permittees must ultimately attain WQBELs and meet receiving water limitations by the specified deadlines and must include control measures that provide reasonable assurance those limitations will be attained. Such controls necessarily take time to design and construct. But it is to the maximum benefit of the people of the State that such controls be designed and implemented properly to be protective of water quality in the long run. These measures that control impacts from stormwater and nonstormwater discharges in the Order are typically effective across multiple pollutants. The alternatives would concurrently address other constituents of

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concern that may not be causing impairment but may still be leading to degradation, resulting in improvements in levels of many pollutants, including pollutants for which the receiving water may be high quality. (a) Alternatives 3 and 4 avoid the high economic and social costs associated with decreased public services analyzed above in section IV.G.2.b.i of this antidegradation analysis. At the same time, Alternatives 3 and 4 provide additional economic and social benefits to the people of the State by incentivizing and incorporating projects that include multiple benefits beyond water quality protection. These additional benefits may support local community goals such as recreation, promotion of walkable communities and non-motorized transportation, increased water supplies, improved wildlife habitat, and flood control.
(b) Multi-benefit projects – that is, projects that fund stormwater capture that provide multiple benefits like those emphasized in WMPs – are actively encouraged by the State of California. Programs such as those funded by the Water Quality, Supply, and Infrastructure Improvement grants (Proposition 1) and Integrated Regional Water Management Grants (Proposition 84) promote collaborative efforts by stakeholders with sometimes competing goals and objectives. This collaborative approach helps stakeholders maximize the projects’ benefits as compared to projects with a single purpose or limited purposes in mind. One example of this is the Mill Creek Wetlands project in the City of Ontario. In addition to water quality benefits, the Wetlands incorporated design features that provide recreational and educational amenities that supported the goals of the City, the Corps of Engineers, and other stakeholders in the watershed.
(c) The Permittees have a long tradition of collaboration involving sharing resources and coordination for compliance with MS4 permits and supporting TMDL development. Collaboration has occurred at both the county and watershed scales. WMPs align with this tradition and support the collaborative approach. The reasonable assurance analysis required by WMPs is likely to indicate a need for increased investment in treatment and source control measures. However, the predictive modeling effort in WMPs is likely to offset some of the higher earlier costs by avoiding inefficiencies. Consequently, with WMPs, the benefits of compliance would be realized sooner. iv. Alternative 3 is nevertheless not to the maximum benefit of the people of the State, because it is less likely than Alternative 4 to result in the anticipated economic and social development described in section IV.G.2.b.iii above. WMPs with the broader deemed compliance option (Alternative 4) better incentivize building and investing in long-term structural and non-structural controls that will improve water quality in the long run for multiple constituents and with multiple benefits. One reason is that deeming Permittees in compliance with receiving water limitations/WQBELs while they are building and investing in multi-benefit projects is necessary to accommodate the planning and design process, the public bidding process (which

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many municipalities must go through to initiate construction) and the construction process, which can take approximately 5-7 years. Deeming Permittees in compliance while they are implementing their WMP projects allows Permittees to focus on constructing multi-benefit projects and long-term water sustainability planning, instead of focusing immediately (and spending money) on fixing violations or defending litigation related to those violations that might occur before their projects are completed. Having determined that water quality is most effectively protected by requiring Permittees to take a thoughtful, proactive watershed management approach to discharges, which also encourages water supply augmentation and has environmental benefits, the Santa Ana Water Board finds that fairness and good public policy also advises against requiring them to comply with all effluent and receiving water limitations immediately (and potentially penalizing them for not doing so). Without the deemed compliance approach, Permittees are expected to shift at least some of their limited resources budgeted for planned, comprehensive, long-term, multi-benefit projects, to measures that are reactive, short-term, and ultimately less effective or protective of water quality in the long run.
v. Alternative 4 is necessary to accommodate important economic and social development and to the maximum benefit of the people of the State, because coupling the WMP framework with deemed compliance status also incentivizes collaboration to implement the most cost-effective controls. The kinds of projects built under the WMP framework with deemed in compliance status should facilitate investment and construction of multi-benefit projects that include parks, infiltration, and low impact development (among other things) in communities that might not have otherwise seen that investment. In the Los Angeles Region, which has implemented WMPs since 2012, there was ample testimony to this effect at the Los Angeles Water Board Meeting held on July 16, 2021. In sum, Alternative 4 has the greatest chance of success, within the shortest time frame, and furthers the goal of maintaining and achieving water quality standards. vi. As detailed above, trend analyses have not been completed for each waterbodypollutant combination in the Santa Ana Region. There is a possibility that water quality has degraded or will degrade during the term of this Order for some of the over 8,000 waterbody-pollutant combinations. This is possible for all alternatives considered above. Moreover, no alternative results in a situation where an optimized system of controls manifests shortly after the effective date of this Order.

A more realistic goal is to compel Permittees to implement that system as soon as possible. If a compliance deadline is established for a pollutant, as with waste load allocations, then that system should be effective as soon as possible but no later than the final compliance deadline. Alternative 4 is most likely to achieve these goals in the most efficient manner. Therefore, degradation that may occur while that system of controls is being developed is to the maximum benefit of the people of the State.
vii. Alternative 4 may result in limited degradation of high quality waters that are currently impaired waters that may nevertheless be considered high quality waters

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based on the historic baseline. The federal antidegradation policy does not require consideration of economic and social costs associated with degradation; it only requires findings that “allowing lower water quality is necessary to accommodate important economic or social development in the area in which the waters are located.” The State antidegradation policy does not define the exact factors that must be considered in determining “maximum benefit to the people of the state.” APU 90-004 states that factors to be considered in a complete antidegradation analysis include economic and social costs of the discharge compared to its benefits, but this Order is subject only to a simple antidegradation analysis. The Santa Ana Water Board has nevertheless considered the costs associated with water quality degradation that may occur under Alternative 4 but has done so at a generalized level. Specifically, in choosing Alternative 4 over Alternative 3, the Santa Ana Water Board finds as follows:

1. There are significant environmental, public health, and economic costs associated with exceedances of water quality objectives. Southern California’s local economy thrives on a healthy environment, as does the health of its population. By way of example, the failure to control stormwater runoff (which would result in exceedances of water quality objectives) would, among other things, negatively impact ocean water quality, which would negatively impact the coastal economy, including tourism and the fishing industry. Similarly, the failure to meet water quality objectives in ocean waters would negatively impact recreation and public health of beachgoers.

2. Where Alternative 4 may allow a currently high quality waterbody to degrade below water quality objectives, or where it will allow a currently impaired, but historically high quality waterbody to stagnate or worsen in quality, even for multiple years, this allowance is for a finite period of time, defined by the compliance schedule specified in the Order and the approved WMP. The Santa Ana Water Board finds that the temporary degradation is justified based on the social and economic benefits discussed in section VII of this Fact Sheet, which is associated with Alternative 4, notwithstanding the potential costs of degradation. In particular, the Santa Ana Water Board anticipates that the system of controls that are designed and implemented over a longer timeframe are more likely to lead to water quality improvements. Any such degradation over a limited period is also consistent with federal regulations and state law allowing for implementation schedules and compliance periods.

3. Alternative 4 could potentially avoid some of the costs discussed in section VII of the Fact Sheet, because some Permittees may correct some exceedances earlier if required to comply immediately with receiving water limitations. From a practical perspective, however, the Santa Ana Water Board finds that immediate compliance, particularly for those waters that may have been high quality historically but are not high quality currently, is unrealistic even if required, given the technical and financial constraints faced by Permittees.

Since Permittees will not be able to afford to immediately comply, any costs avoided would be minimal.

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viii. For all of the reasons set forth above, the Santa Ana Water Board finds that any lowering of high quality waters under this Order’s structure, which is consistent with Alternative 4 and components of Alternatives 1 and 2, is necessary to accommodate important economic or social development in the Santa Ana Region and is to the maximum benefit of the people of the State. c. Requirement for Highest Statutory and Regulatory Requirements and Best Practicable Treatment or Control: The Order requires the highest statutory and regulatory requirements and requires that the Permittees meet best practicable treatment or control:
i. The Order prohibits all non-stormwater discharges, with a few enumerated exceptions, through the MS4 to all receiving waters.
ii. As required by 40 CFR section 122.44(a), Permittees must comply with the “maximum extent practicable” technology-based standard set forth in CWA section 402(p)(3)(B)(iii) and implement the minimum control measures required of a stormwater management program by 40 CFR section 122.26(d)(2)(iv). iii. As required by CWA section 402(p)(3)(B)(iii) and 40 CFR section 122.44(d)(1)(vii)(B), Permittees must comply with applicable WQBELs based on TMDL WLAs established for waters in the Santa Ana Region. iv. The Order also contains provisions to encourage, wherever feasible, retention of stormwater from the 85th percentile, 24-hour storm event, consistent with State Water Board Order WQ 2015-0075.
v. The measures that control impacts from stormwater and non-stormwater discharges in the Order are typically effective across multiple pollutants. For example, retention basins, low-impact development controls, and low flow diversions avert stormwater and non-stormwater from reaching the receiving water at all—preventing degradation to the receiving water from multiple types of constituents. The WMP provisions contained in the Order are designed to achieve water quality standards for those constituents that are impairing the receiving water, as well as to address other constituents of concern that may not be causing impairment as defined in CWA section 303(d) and State policy. The WMPs developed pursuant to these provisions will likely result in improvements in levels of all pollutants, including those for which the receiving water may be high quality.

As a final backstop against degradation, the Order includes an extensive monitoring and reporting program, including monitoring of MS4 discharges at representative outfalls and in receiving waters for pollutants of concern in receiving waterbodies; monitoring during both wet weather and dry weather conditions; and analysis of toxicity in receiving waters.

Monitoring data must be submitted annually, and the Order also includes reopener provisions to allow modification of the Order as necessary to add preventative provisions if a threat of degradation is suspected. The monitoring and reporting requirements are sufficient to identify and address changes in water quality.

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H. Anti-backsliding Requirements
Clean Water Act sections 402(o) and 303(d)(4) and 40 CFR 122.44(l) generally prohibit backsliding in NPDES permits. These anti-backsliding provisions require effluent limitations in a reissued permit to be at least as stringent as those in previous permits, with some exceptions where effluent limitations may be relaxed.

1. Summary of Effluent Limitation Changes
In general, the effluent limitations in the Order are at least as stringent as the effluent limitations in the prior permits, Order Nos. R8-2009-0030, R8-2010-0033, and R8- 2010-0036. However, certain of the effluent limitations in the Order are not identical to the effluent limitations in the previous MS4 permits because the Order implements revisions to TMDLs that occurred after these permits were adopted. A summary of changes to the effluent limitations from Order Nos. R8-2009-0030, R8-2010-0033, and R8-2010-0036 are summarized in Tables D.2 to D.4 below.33 While not all of the changes to these effluent limitations constitute backsliding, the rationale for each change is discussed below.

Table D.2 - Summary of Changes to Effluent Limitations in Order R8-2009-0030 TMDL Constituent Waterbody Existing Limitation New Limitation Nutrients in the Newport Bay/San Diego Creek Watershed Total Nitrogen
Newport Bay
55,442 lbs/ Winter season
(Oct-Mar) No Change
16,628 lbs/ Summer season
(Apr-Sept) No Change
San Diego
Creek 5.5 lbs/day No Change
Total
Phosphorus Newport Bay 2,960 lbs/year No Change
Fecal Coliform in Newport Bay
Fecal Coliform
for REC1 Newport Bay
5-Sample/30-days
Geometric Mean less than
200 Organisms/100 mL,
and not more than 10% of
the samples exceed 400
Organisms/ 100 mL for any
30-day period
No Change
Fecal Coliform
for SHEL Newport Bay
Monthly Median less than
14 MPN/100 mL, and not
more than 10% of the
samples exceed 43
MPN/100 mL
No Change.

Compliance deadline
extended to
December 31, 2030,
in accordance with
R8-2022-0017
33 Tables D.2 to D.4 are for the convenience of the reader only. The Tables do not substitute for a reading of or supersede provisions in the Order.

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Hemet City CouncilSeptember 10, 2024

Hemet City Council
September 10, 2024