Hermosa Beach City Council
March 10, 2026

Mr. Doug Krauss
November 6, 2025

Provide a Summary of Site Conditions and Constraints, summarizing the findings from the background research.

Task 3 – Hydrology and Hydraulics Study
Geosyntec will perform hydrologic and hydraulic (H&H) calculations and modeling to support Project design and justify the water quality and water supply benefits. The study will summarize the approach and results of the following:

Drainage area delineations
Peak flow and run-off volume calculations for the Design Storm and 85th Percentile, 24-hour Storm, using HydroCalc
Long-term Pollutant load reduction calculations, using WMMS and SCWP Project Module
SCWP Water Quality and Water Supply Scoring Analyses
One draft and one final H&H study technical memorandum will be submitted to the Cities.

Task 4 – Feasibility Study Report
Geosyntec will prepare a draft and final Feasibility Study that meets the requirements set forth in the latest SCWP Feasibility Study Guidelines. A preliminary design effort will be taken and incorporated into the final Feasibility Study. Additional documentation and evaluation will be developed for the preferred alternative and attached to the Feasibility Study, including:

Identification and conceptualization of additional green infrastructure features to supplement the drywells
10% design set (Site plan and BMP details)
Opinion of Probable Construction Cost (OPCC)
Project Description
CEQA Screening Checklist
Develop a community outreach and engagement plan, which identifies key stakeholders and agencies.

Subtask will include a digital copy of the draft Feasibility Study to be submitted for one round of comments, and a digital copy of the final Feasibility Study with documented responses to comments. Up to two meetings will be held to review the Feasibility Study findings and feedback from the Cities.

Mr. Doug Krauss
November 6, 2025

Task 5 – SCWP Module Submission and Meeting Support
Geosyntec will generate a Project fact sheet in accordance with the SCWP template and complete the SCW Module for the Project based on the final Feasibility Study. Completion of the module will include filling required entries and uploading supporting documentation. A draft module output will be provided to the Cities 20 days prior to the SCWP application deadline (July 31st, 2025).

Geosyntec will address changes to the module and produce a final module output for client approval 5 days prior to the SCWP application deadline. Once approval is received, Geosyntec will submit the SCWP application. Geosyntec will assist in modifying the application entries and supporting documents should comments be received from the SCWP.

Geosyntec will support the Cities and participate in up to two (2) virtual and two (2) in-person calls and meetings, including the Scoring Committee and South Santa Monica Bay Watershed Area Steering Committee meetings. Geosyntec will prepare one PowerPoint presentation based on the SWCP template.

CLOSURE
We are looking forward to working with the City on this important Project. Should you have any questions or need additional information, please do not hesitate to contact Christopher Wessel at (714) 606-6215.

Sincerely,
Chris Wessel, PE Senior Principal Curtis Fang, PE, PMP, Senior Enginee

EXHIBIT “B”

FEE AND PHASING/FUNDING SCHEDULES (SEE ATTACHED EXHIBIT B)

1. FEE SCHEDULE.

Designer will invoice City on a monthly cycle based on the following fee schedule. Designer will include with each invoice a detailed progress report that indicates the amount of budget spent on each phase and the total amount spent against the Total Compensation. Designer will inform City regarding any out-of-scope work being performed by Designer for which Designer intends to seek compensation from City.

GEOSYNTEC CONSULTANTS 2026 U.S. RATE SCHEDULE
Staff Professional $185
Senior Staff Professional $210
Professional $239
Project Professional $268
Senior Professional $300
Principal $325
Senior Principal $345
Senior Designer $225
Designer $190
Senior Drafter/Senior CADD Operator $175
Drafter/CADD Operator/Artist $158
Project Administrator $104
Clerical $ 84
Direct Expenses Cost plus 12%
Subcontract Services Cost plus 12%
Personal Automobile (per mile) Current Gov’t
Rate
Rates are provided on a confidential basis and are client and project specific.

Unless otherwise agreed, rates will be adjusted annually based on a minimum of the BLS reported change in the average hourly earnings of all employees, engineering and drafting services.

Rates for field equipment, health and safety equipment, and graphical supplies presented upon request.

Construction management fee presented upon request.

1. PHASING/FUNDING SCHEDULE.

Progress payments towards Total Compensation shall never exceed the following percentages of Total Compensation as of the phase indicated:

Task Subtotal
Task 1 – Project Management and Outreach $22,500
Task 2 - Background Research and Field Verification $5,400 Task 3 - Hydrology and Hydraulics Study $9,900
Task 4 - Feasibility Study Report $21,300
Task 5 - SCWP Module Submission and Meeting Support $5,900 Total $65,000
The Project will be billed on a time and materials basis and invoiced monthly. See Attachment 1 for the billing rate. Each monthly invoice will be accompanied by a progress report detailing the services performed for the invoice period.

Assumption and Exclusions
The following assumptions and exclusions apply to the Project as scoped:

Geosyntec anticipates that Los Angeles County will revise the SCWP application guideline, which will separate the current application process into two: A design fundingonly application process and a construction funding application process. Since the County has not published the revised application guideline. The scope of work reflects our anticipated requirement for the design funding-only

application. We will discuss with the Cities if the revised application guideline requires additional elements that are not covered in the scope work provided herein.

It is assumed that the Cities will coordinate with the shareholders and agencies directly to obtain letters of support, if such items are required for a design funding only SCWP Application.

Geosyntec will rely on the work completed to-date for the Project, including the initial Project screening, desktop environmental and geotechnical study that Geosyntec completed in 2023.

Unless otherwise specified, all deliverables will be provided electronically.

Unless otherwise specified, meetings will occur virtually

ENHANCED WATERSHED

MANAGEMENT PROGRAM
(EWMP)
for the Beach Cities Watershed Management
Area (Santa Monica Bay and Dominguez
Channel Watersheds)
Submitted to:

Los Angeles Regional Water Quality Control Board
Submitted by:

Beach Cities EWMP Group
March 2018

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TABLE OF CONTENTS
Executive Summary.......................................................................................................................................................ES-1 Purpose and Objectives...........................................................................................................................................ES-1 Santa Monica Bay Watershed...............................................................................................................................ES-4 Dominguez Channel Watershed .......................................................................................................................ES-17 Compliance Schedule ............................................................................................................................................ES-29 Planning Level Cost Opinion ..............................................................................................................................ES-34 Financing Discussion.............................................................................................................................................ES-36 1 Introduction.............................................................................................................................................................. 1-1

1.1 Purpose and Regulatory Framework.................................................................................................... 1-1

1.2 Applicability of EWMP ................................................................................................................................ 1-4

1.3 EWMP Development Process ...................................................................................................................1-7

1.4 Report Organization.................................................................................................................................. 1-10

1.5 Terms of Reference.................................................................................................................................... 1-10 2 Santa Monica Bay Watershed ............................................................................................................................ 2-1

2.1 Background...................................................................................................................................................... 2-1

2.2 Identification of Water Quality Priorities............................................................................................2-4

2.3 Selection of Appropriate Best Management Practices................................................................ 2-18

2.4 Reasonable Assurance Analysis Approach...................................................................................... 2-23

2.5 Baseline Loads and Target Load Reductions.................................................................................. 2-34

2.6 Best Management Practices................................................................................................................... 2-39

2.7 Reasonable Assurance Analysis Results........................................................................................... 2-68

2.8 Multiple Benefits ........................................................................................................................................ 2-71

2.9 Parallel Compliance Efforts.................................................................................................................... 2-73 3 Dominguez Channel Watershed .......................................................................................................................3-1

3.1 Background...................................................................................................................................................... 3-1

3.2 Identification of Water Quality Priorities............................................................................................ 3-4

3.3 Selection of Appropriate Best Management Practices................................................................ 3-20

3.4 Reasonable Assurance Analysis Approach...................................................................................... 3-21

3.5 Baseline Loads and Target Load Reductions.................................................................................. 3-32

3.6 Best Management Practices................................................................................................................... 3-35

3.7 Reasonable Assurance Analysis Results........................................................................................... 3-48

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3.8 Multiple Benefits ........................................................................................................................................ 3-52

3.9 Parallel Compliance Efforts.................................................................................................................... 3-52 4 Implementation Schedule.................................................................................................................................... 4-1

4.1 Compliance Schedule................................................................................................................................... 4-1

4.2 Project Sequencing .......................................................................................................................................4-7 5 Assessment and Adaptive Management Framework...............................................................................5-1 6 Financial Analysis ...................................................................................................................................................6-4

6.1 BMP Cost Methodology and Assumptions ..........................................................................................6-4

6.2 Proposed Structural BMPs ........................................................................................................................ 6-7 7 Potential Funding Sources and Financial Strategy ...................................................................................7-1

7.1 Grant Opportunities ..................................................................................................................................... 7-2

7.2 Project-Specific Interagency Partnerships ......................................................................................... 7-7

7.3 Local Bond Issuance..................................................................................................................................... 7-7

7.4 State Revolving Funds................................................................................................................................. 7-8

7.5 Local Public Funding Opportunities and Approval Procedures ................................................7-9

7.6 Public Private Partnerships ................................................................................................................... 7-12

7.7 Financial Strategy....................................................................................................................................... 7-13

7.8 Watershed Management Program Budgets .................................................................................... 7-15 8 Legal Authority ........................................................................................................................................................8-1 9 References.................................................................................................................................................................. 9-2

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LIST OF FIGURES
Figure ES-1. Beach Cities EWMP Area ........................................................................................................ES-5 Figure ES-2. Analysis Regions and Compliance Monitoring Locations within the SMB Watershed portion of the Beach Cities EWMP Area .............................................................................ES-8 Figure ES-3. Proposed Project Sequencing in the Santa Monica Bay Watershed ..................ES-17 Figure ES-4. Analysis Regions within the Dominguez Channel Watershed portion of the Beach Cities EWMP Area............................................................................................................................................. ES-21 Figure ES-5. Project Sequencing in the Dominguez Channel Watershed..................................ES-28 Figure 1-1. Beach Cities EWMP Area............................................................................................................. 1-5 Figure 2-1. Beach Cities WMG MS4 Infrastructure within the Santa Monica Bay Watershed . 2- 2 Figure 2-2. Beach Cities WMG Land Uses within the Santa Monica Bay Watershed................ 2-3 Figure 2-3. Process for Categorizing Water Body-Pollutant Combinations................................2-10 Figure 2-4. Non-Stormwater Outfall Screening Program ...................................................................2-22 Figure 2-5. Analysis Regions and Monitoring Locations within the SMB Watershed portion of the Beach Cities EWMP Area...........................................................................................................................2-25 Figure 2-6. SBPAT Model Data Flow............................................................................................................2-27 Figure 2-7. SBPAT Monte Carlo Method Components .........................................................................2-28 Figure 2-8. SBPAT Rain and Stream Gauges.............................................................................................2-29 Figure 2-9. Annual Runoff Volumes for Topanga Creek Subwatershed: Modeled vs. Observed. .....................................................................................................................................................................................2-32 Figure 2-10. Annual Runoff Volumes for Topanga Creek Subwatershed: Modeled vs. Observed (Flow Duration Curve Format). .....................................................................................................................2-33 Figure 2-11. Correlation between Modeled Fecal Coliform Loads and Observed Exceedance Days (each point represents one TMDL year, 2005-2013)................................................................2-34 Figure 2-12. IGP and Caltrans Area within the Santa Monica Bay portion of the Beach Cities EWMP Area ............................................................................................................................................................2-53 Figure 2-13. Existing and Proposed Regional BMPs within EWMP Area.....................................2-54 Figure 2-14. Existing and Proposed Distributed BMP Locations within the EWMP Area....2-55 Figure 2-15. Proposed Regional Projects, Analysis Region SMB-5-02..........................................2-62 Figure 2-16. Proposed Regional Projects, Analysis Region SMB-6-01..........................................2-64 Figure 3-1. Beach Cities WMG MS4 Infrastructure within the Dominguez Channel Watershed ....................................................................................................................................................................................... 3-2 Figure 3-2. Beach Cities WMG Land Uses within the Dominguez Channel Watershed........... 3-3 Figure 3-3. Analysis Regions within the Dominguez Channel Watershed portion of the Beach Cities EWMP Area................................................................................................................................................3-23 Figure 3-4. Annual Runoff Volumes Predicted by LSPC and SBPAT...............................................3-28

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Figure 3-5. Annual Runoff Volumes Predicted by LSPC and SBPAT..............................................3-29 Figure 3-6. Comparison of Fecal Coliform High Density Residential EMC Values between SCCWRP Measurements (n=7) and Multi-Family Residential EMC distribution in SBPAT..3-30 Figure 3-7. Comparison of Total Zinc Multi Family Residential EMC Values between Los Angeles County Measurements (n=4) and Multi-Family Residential EMC distribution in SBPAT .....................................................................................................................................................................................3-31 Figure 3-8. IGP and Caltrans Area within the Dominguez Channel portion of the Beach Cities EWMP Area ............................................................................................................................................................3-40 Figure 3-9. Proposed Distributed BMPs within the Dominguez Channel Watershed ............3-41 Figure 3-10. Proposed Regional BMPs within the Dominguez Channel Watershed ...............3-42 Figure 3-11. Proposed Regional BMPs, DC-RB/MB Analysis Region.............................................3-45 Figure 4-1. Proposed Project Sequencing ................................................................................................... 4-8 Figure 5-1. Adaptive Management Approach............................................................................................ 5-3

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LIST OF TABLES
Table ES-1. Beach Cities WMG Area Distribution by Participating Agency................................. ES-3 Table ES-2. Water Body-Pollutant Combination Prioritization for the Santa Monica Bay Watershed ..............................................................................................................................................................ES-6 Table ES-3. Water Quality Targets for Modeled Pollutants in the Santa Monica Bay Watershed .....................................................................................................................................................................................ES-7 Table ES-4. TLRs for Fecal Coliform in the Santa Monica Bay Watershed................................ES-10 Table ES-5. Proposed Structural BMPs in the Santa Monica Bay Watershed..........................ES-13 Table ES-6. Santa Monica Bay Watershed – Fecal Coliform Reasonable Assurance Analysis Results – Interim and Final Compliance ................................................................................................. ES-16 Table ES-7. Water Body-Pollutant Prioritization for the Dominguez Channel Watershed ... ES18 Table ES-8. Water Quality Targets for the Dominguez Channel Watershed............................ES-19 Table ES-9. TLRs and Baseline Conditions for Pollutants in the Dominguez Channel Watershed ..................................................................................................................................................................................ES-23 Table ES-10. Proposed Structural BMPs in the Dominguez Channel Watershed ..................ES-24 Table ES-11. Dominguez Channel Watershed – Reasonable Assurance Analysis Results – Interim and Final Compliance.....................................................................................................................ES-27 Table ES-12. Compliance Schedule for the Santa Monica Bay and Dominguez Channel Watersheds ......................................................................................................................................................... ES-30 Table ES-13. Cost Opinion for Proposed Structural BMPs in Santa Monica Bay and Dominguez Channel Watersheds ....................................................................................................................................... ES-35 Table 2-1. Beach Cities WMG EWMP Area Distribution by Participating Agency ...................... 2-1 Table 2-2. Beach Cities EWMP Area - Santa Monica Bay Watershed Water Bodies and Beneficial Uses........................................................................................................................................................ 2-6 Table 2-3. Water Body-Pollutant Combination Prioritization and Pollutant Interim and Final Compliance Targets for Santa Monica Bay Watershed Portion of the Beach Cities EWMP Area .....................................................................................................................................................................................2-11 Table 2-4. Bacteria RLWs for Beach Cities WMG Shoreline Monitoring Stations....................2-12 Table 2-5. Rainfall Summary at Manhattan Beach Precipitation Gauge (Station ID 1070)..2-30 Table 2-6. BMPS and Constituents Modeled in SBPAT1.......................................................................2-31 Table 2-7. Target Load Reductions for Fecal Coliform for each Modeled Analysis Region in Santa Monica Bay Watershed - TMDL Year 1995 ..................................................................................2-38 Table 2-8. MCM Modifications and Agency-Specific Enhancements for Beach Cities EWMP Area ...........................................................................................................................................................................2-42 Table 2-9. Estimated Annual Redevelopment Rates............................................................................2-48 Table 2-10. Redevelopment and Public Retrofit Incentives Model Assumptions ...................2-51

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Table 2-11. Non-MS4 Parcels – Modeled as Treated by Treatment Plants (i.e., BMPs that will treat stormwater to the Water Quality Objectives)...............................................................................2-52 Table 2-12. Parameters and Performance for Existing Regional BMPs Modeled as Infiltration Basins .......................................................................................................................................................................2-59 Table 2-13. Parameters and Performance for Existing Regional BMPs Modeled as Wet Ponds with Extended Detention..................................................................................................................................2-60 Table 2-14. Parameters and Performance for Proposed Regional BMPs Modeled as Infiltration Basins .......................................................................................................................................................................2-65 Table 2-15. Existing and Proposed Distributed BMPs .........................................................................2-67 Table 2-16. Existing and Proposed Distributed BMP Performance................................................2-68 Table 2-17. Santa Monica Bay Watershed – Fecal Coliform RAA Results – Interim and Final Compliance.............................................................................................................................................................2-69 Table 2-18. Dry Weather RAA Evaluation of Santa Monica Bay Watershed CMLs .................2-71 Table 3-1. Beach Cities WMG Area Distribution by Participating Agency ..................................... 3-1 Table 3-2. Beach Cities EWMP Area – Dominguez Channel Watershed Water Bodies and Beneficial Uses........................................................................................................................................................ 3-4 Table 3-3. LACDPW Monitoring Results Summary ................................................................................. 3-8 Table 3-4. Water Body-Pollutant Combination Prioritization and Pollutant Interim and Final Compliance Targets for Dominguez Channel Watershed...................................................................3-11 Table 3-5. RAA Models Used in the Dominguez Channel Watershed ............................................3-24 Table 3-6. Wet Weather Permit Limits (Final Compliance Limits for Modeled Pollutants).3-25 Table 3-7. Mean Annual Volume Predicted by SBPAT and LSPC and Measured at the S28 Stream Gauge ........................................................................................................................................................3-28 Table 3-8. Baseline Runoff, Concentration, and Load for Pollutants in the Dominguez Channel Watershed for the Critical Condition ..........................................................................................................3-32 Table 3-9. Target Load Reductions and Baseline Conditions for Pollutants in the Dominguez Channel Watershed for the Critical Condition.........................................................................................3-35 Table 3-10. Estimated Annual Redevelopment Rates.........................................................................3-37 Table 3-11. Parameters and Performance for Proposed Regional BMPs Modeled as Media Filters ........................................................................................................................................................................3-46 Table 3-12. Dominguez Channel Watershed – RAA Results – Interim and Final Compliance.. 3- 51 Table 4-1. Compliance Deadlines associated with Santa Monica Bay Watershed WBPCs...... 4-1 Table 4-2. Implementation Actions and Dates associated with Dominguez Channel Watershed WBPCs........................................................................................................................................................................ 4-4 Table 6-1. Range of Soft Costs for Proposed Structural BMP Projects as a Percent of Capital . 6- 6 Table 6-2. Proposed BMP Design Assumptions for Conceptual Cost Opinions ........................... 6-8

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Table 6-3. Estimated Construction and O&M Costs for Structural BMPs in Analysis Region SMB-5-02, Alternative 1....................................................................................................................................6-11 Table 6-4. Estimated Construction and O&M Costs for Structural BMPs in Analysis Region SMB-5-02, Alternative 2....................................................................................................................................6-12 Table 6-5. Estimated Construction and O&M Costs for Structural BMPs in Analysis Region SMB-6-01 ................................................................................................................................................................6-14 Table 6-6. Estimated Construction and O&M Costs for Structural BMPs in Analysis Region DCRB/MB1 ....................................................................................................................................................................6-16 Table 6-7. Estimated Construction and O&M Costs for Structural BMPs in Analysis Region DCTorrance ..................................................................................................................................................................6-17 Table 6-8. Estimated Construction and O&M Costs for Catch Basin Retrofits ...........................6-18 Table 6-9. Capital, O&M, and 20-year Life-Cycle Cost Opinion for Proposed Structural BMPs by Analysis Region....................................................................................................................................................6-22 Table 7-1. Relevant Grant Opportunities .................................................................................................... 7-4 Table 7-2. Added Benefits of Interagency Partnership for Stormwater Management............. 7-7 Table 7-3. Local Funding Opportunities ....................................................................................................7-10 Table 7-4. Local Funding Approval Mechanisms....................................................................................7-11 Table 7-5. Selected Cities that provide Financial Subsidies to encourage the Development of Stormwater Infrastructure in Private Properties ..................................................................................7-13 Table 7-6. Funding Approach Summary ....................................................................................................7-14 Table 7-7. Watershed Management Program Budgets for the Beach Cities WMG..................7-15

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LIST OF APPENDICES
A. Notice of Intent
B. Reasonable Assurance Analysis for Dominguez Channel Watershed within the City of Torrance C. City of Redondo Beach Area Located within Machado Lake Watershed D. City of Redondo Beach Tributary to Machado Lake
E. City of Redondo Beach Request for Withdrawal and/or Exemption from Machado Lake Trash TMDL—Region 4
F. Machado Lake Trash TMDL – Redondo Beach Watershed Contribution G. Background Information on the LACFCD
H. Approach to Addressing Receiving Water Exceedances
I. Land Use-Based Wet Weather Pollutant EMCs
J. BMP Effluent Concentrations
K. Sample RAA Calculations
L. MCM Customization Summary
M. LID Ordinances
N. Green Streets Policies
O. Structural BMP Unit Cost Tables
P. Documentation of Legal Authority
Q. Selection of Critical Condition
R. Ammonia Monitoring Data from Sites S28 and TS19

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LIST OF ACRONYMS
AED Allowable Exceedance Days
ASBS Area of Special Biological Significance
ASCE American Society of Civil Engineers
BMP Best Management Practice
Caltrans California Department of Transportation
CERCLA Comprehensive Environmental Response, Compensation, & Liability Act CFCC California Financing Coordinating Committee
cfs Cubic feet per second
CIMP Coordinated Integrated Monitoring Program
CML Compliance Monitoring Location
CNT Center for Neighborhood Technology
COMM Commercial and Sport Fishing
Conc. Concentration
CSMP Coordinated Shoreline Monitoring Plan
CTR California Toxic Rules
cu-ft Cubic feet
CWA Clean Water Act
CWSRF Clean Water State Revolving Fund
DC Dominguez Channel
DCu Dissolved Copper
DDT Dichloro-diphenyl-trichloroethane
DP Dissolved Phosphorus as P
DZn Dissolved Zinc
EIFD Enhanced Infrastructure Financing Districts
EMC Event Mean Concentration
EWMP Enhanced Watershed Management Program
FAA Federal Aviation Administration
FC Fecal coliform
FIB Fecal Indicator Bacteria
ft Foot
GIS Geographic Information System
GM Geometric Mean
GO General Obligation
gpm Gallons per minute
HFS High Flow Suspension
HSPF Hydrological Simulation Program - Fortran
IBD International BMP Database
IC/ID Illicit Connection/Illicit Discharge
IDDE Illicit Discharge Detection and Elimination
IGP Industrial General Permit
in inch
IND Industrial Service Supply
in/hr Inches per hour

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IPM Integrated Pest Management
J5&6 Jurisdictional Groups 5 and 6
JPA Joint Powers Authority
LACFCD Los Angeles County Flood Control District
LADWP Los Angeles Department of Water and Power
LARWQCB Los Angeles Regional Water Quality Control Board lb Pound
LID Low Impact Development
LSPC Loading Simulation Program C++
MAR Marine Habitat
MB Manhattan Beach
MCM Minimum Control Measure
MEP Maximum Extent Practical
MIGR Migration of Aquatic Organisms
min Minute
MPN Most Probable Number
MS4 Municipal Separate Storm Sewer System
MUN Municipal and Domestic Supply
NAV Navigation
NH3 Ammonia as N
NO3 Nitrate as N
NOI Notice of Intent
NPDES National Pollutant Discharge Elimination System
O&M Operations and Maintenance
OM&R Operations, Maintenance, and Replacement
PCB Polychlorinated Biphenyl
PIPP Public Information and Participation Program
RAA Reasonable Assurance Analysis
RARE Rare, Threatened, or Endangered Species
RB Redondo Beach
REC-1 Water Contact Recreation
REC-2 Non-Contact Water Recreation
RWL Receiving Water Limitation
SBPAT Structural BMP Prioritization and Analysis Tool
SCCWRP Southern California Coastal Watershed Research Project SCPWA Southern California Public Water Authority
SFPUC San Francisco Public Utilities Commission
SHELL Shellfish Harvesting
SMB Santa Monica Bay
SMBBB Santa Monica Bay Beaches Bacteria
SPWN Spawning, Reproduction, and/or Early Development
SUSMP Standard Urban Stormwater Management Program
SWMM Storm Water Management Model, originally developed by USEPA SWQDv Storm Water Quality Design Volume
SWQPA State Water Quality Protection Area

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SWRCB State Water Resources Control Board
TAC Technical Advisory Committee
TCu Total Copper
TKN Total Kjeldahl Nitrogen as N
TP Total Phosphorus
TPb Total Lead
TIE Toxicity Identification Evaluation
TLR Total Load Reduction
TMDL Total Maximum Daily Load
TSS Total Suspended Solids
TZn Total Zinc
USEPA United States Environmental Protection Agency
WARM Warm Freshwater Habitat
WBPC Water Body-Pollutant Combination
WDR Waste Discharge Requirement
WER Water Effects Ratio
WERF Water Environment Research Foundation
WET Wetland Habitat
WHAT Web-Based Hydrograph Analysis Tool
WILD Wildlife Habitat
WLA Waste Load Allocation
WMA Watershed Management Area
WMG Watershed Management Group
WMMS Watershed Management Modeling System
WMP Watershed Management Program
WQBEL Water Quality-Based Effluent Limitation
yr Year

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EXECUTIVE SUMMARY

PURPOSE AND OBJECTIVES
Following adoption of the 2012 Los Angeles Municipal Separate Storm Sewer System (MS4) National Pollutant Discharge Elimination System (NPDES) Permit1 (Permit), the Cities of Hermosa Beach, Manhattan Beach, Redondo Beach and Torrance, together with the Los Angeles County Flood Control District (LACFCD), collectively referred to as the Beach Cities Watershed Management Group (Beach Cities WMG) agreed to collaborate on the development of an Enhanced Watershed Management Program (EWMP) for the Santa Monica Bay (SMB) and Dominguez Channel Watershed areas within their jurisdictions (referred to herein as the Beach Cities EWMP Area). The Machado Lake Watershed is being addressed separately by the City of Torrance, and is not addressed in this EWMP.

This EWMP is intended to facilitate effective, watershed-specific Permit implementation strategies in accordance with Permit Part VI.C. Watershed Management Program. This EWMP:
• Summarizes watershed-specific water quality priorities identified by the Beach Cities WMG; • Outlines the program plan, including specific strategies, control measures and best management practices (BMPs)2, necessary to achieve water quality targets (Water QualityBased Effluent Limitations [WQBELs] and Receiving Water Limitations [RWLs]); and • Describes the quantitative analyses completed to support target achievement and Permit compliance.

In compliance with Section VI.C.4.b of the Permit, the Beach Cities WMG submitted to the Los Angeles Regional Water Quality Control Board (LARWQCB) a Notice of Intent (NOI) (Appendix A) to develop an EWMP on June 28, 2013, with a revised NOI submitted December 17, 2013 in response to comments received from LARWQCB staff. On March 27, 2014, the Beach Cities WMG received a letter from the Executive Officer of the LARWQCB approving the revised NOI submittal.

In compliance with Section VI.C.4.c.iv of the Permit, the Beach Cities WMG then submitted a draft EWMP Work Plan to the LARWQCB on June 26, 2014. LARWQCB comments were not received on the EWMP Work Plan; therefore work proceeded on EWMP development consistent with the approach outlined in the EWMP Work Plan. The Beach Cities WMG was required by Section VI.C.4.c.iv of the Permit to submit a draft EWMP no later than June 30, 2015. This document has been developed to serve as the Beach Cities Draft EWMP and is consistent with the Work Plan previously submitted to the LARWQCB.

Watershed Management Programs (WMPs) are a voluntary opportunity afforded by Section VI.C.1 of the Permit for Permittees to collaboratively or individually develop comprehensive watershed-

1 Order No. R4-2012-0175 NPDES Permit No. CAS004001 Waste Discharge Requirements for Municipal Separate Storm Sewer System (MS4) Discharges within the Coastal Watersheds of Los Angeles County, except those Discharges Originating from the City of Long Beach MS4. 2 For simplification, the term “BMP” will be used to collectively refer to strategies, control measures, and/or best management practices. The Permit also refers to these measures as Watershed Control Measures.

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specific control plans and are intended to facilitate Permit compliance and water quality target achievement. Enhanced WMPs (EWMPS) are WMPs which comprehensively evaluate opportunities for collaboration on multi-benefit regional projects that retain all non-stormwater runoff and runoff from the 85th percentile, 24 hour storm event while also achieving benefits associated with issues such as flood control and water supply. Where it is not feasible for regional projects to retain the 85th percentile 24 hour storm, the EWMP must demonstrate through a Reasonable Assurance Analysis, that applicable water quality targets should be achieved. Permittees within the Beach Cities Watershed Management Area (WMA) have elected to prepare an EWMP. The EWMP allows Permittees to collaboratively or individually develop comprehensive watershed-specific control plans which a) prioritize water quality issues, b) identify and implement focused strategies, control measures and BMPs, c) execute an integrated monitoring and assessment program, and d) allow for modification over time. In general, WMPs and EWMPs are intended to facilitate Permit compliance and water quality target achievement and goals that: 1) discharges from covered MS4s achieve applicable WQBELs and RWLs and do not include prohibited non-stormwater discharges; and 2) control measures are implemented to reduce the discharge of pollutants to the maximum extent practicable (MEP). Per Permit Section VI.C.1.e, WMPs and EWMPs are to be developed based on the LARWQCB’s WMAs or subwatersheds thereof.

Consistent with Permit requirements, this EWMP is written to:

1. Be consistent with Permit provisions for EWMPs in Part VI.C.1.a.-f and Part VI.C.5-C.8;

2. Incorporate applicable State agency input on priority setting and other key implementation issues;

3. Provide for meeting water quality standards and other Clean Water Act obligations;

4. Include multi-benefit regional projects which retain stormwater from the 85th percentile 24 hour storm where feasible;

5. Include watershed control measures which achieve compliance with all interim and final WQBELs in drainage areas where retention of the 85th percentile 24 hour storm is infeasible with reasonable assurance;

6. Maximize the effectiveness of funding;

7. Incorporate effective innovative technologies;

8. Ensure existing requirements to comply with technology based effluent limitations and core requirements are not delayed; and

9. Ensure a financial strategy is in place.

This EWMP is applicable to the Beach Cities WMG EWMP Area, which consists of all of the incorporated MS4 areas of the cities of Redondo Beach, Manhattan Beach, Hermosa Beach and Torrance (excluding the Machado Lake Watershed) and includes the infrastructure of the LACFCD within those jurisdictions (Figure ES-1). This area includes portions of two distinct HUC-12

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watersheds3, Santa Monica Bay Watershed and Dominguez Channel Watershed, as summarized in Table ES-1. The Wylie Sump, Bishop Montgomery Basin, and Ocean Basin are all retention basins with no outlet. Therefore, their drainage areas have been excluded from the EWMP Reasonable Assurance Analysis (RAA). The Del Amo Retention Basin also has no outlet, and is sized to capture runoff from at least the 85th percentile, 24 hour storm event. Because the Del Amo Retention Basin is within the Machado Lake Watershed, this drainage area is excluded from the EWMP. • The western portion of the Beach Cities EWMP Area consists of approximately 7,840 acres of land that drains to Santa Monica Bay (SMB). This accounts for 52% of the total Beach Cities WMG area, and includes portions of the cities of Manhattan Beach, Redondo Beach, and Torrance, and the entirety of the City of Hermosa Beach. This portion of the study area is hereinafter referred to as the “SMB Watershed”.
• The northeastern portion of the Beach Cities EWMP Area is tributary to Dominguez Channel (including Torrance Carson Channel) and is comprised of approximately 7,380 acres of land.

This watershed accounts for 48% of the total Beach Cities EWMP Area, and includes portions of the cities of Manhattan Beach, Redondo Beach, and Torrance. Storm drains from the Cities of Manhattan Beach and Redondo Beach drain through the City of Lawndale before discharging to Dominguez Channel. The City of Torrance’s MS4 discharges directly to Dominguez Channel and Torrance Carson Channel (Torrance Lateral). Collectively, this portion of the study area is hereinafter referred to as the “Dominguez Channel Watershed”.

Table ES-1. Beach Cities WMG Area Distribution by Participating Agency Participating Agency
Area (acres)
Santa Monica Bay
Watershed
Dominguez Channel
Watershed
Total EWMP Area
(% of total)
City of Redondo Beach 2,614 1,217 3,831 (25%)
City of Manhattan Beach 2,078 350 2,428 (16%)
City of Hermosa Beach 832 - 832 (5%)
City of Torrance 2,314 5,812 8,126 (53%)
Total 7,837 7,379 15,217 (100%)
The EWMP approach, including model selection, data inputs, critical condition selection, calibration performance criteria, and output types is consistent with the LARWQCB Reasonable Assurance Analysis Guidance Document (LARWQCB, 2014) and also leverages previous efforts where relevant models have already been developed. The individual water quality targets, BMPs, Reasonable Assurance Analyses, schedules, and costs for each of the watersheds are summarized in watershedspecific sections that follow.

3 A HUC-12 watershed is defined by a 12-digit hydrologic unit code (HUC) delineation, which identifies the watershed area based on six levels of classification: regional, sub-region, hydrologic basin, hydrologic subbasin, watershed, and subwatershed.

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SANTA MONICA BAY WATERSHED
Receiving waters for stormwater runoff from the Beach Cities EWMP Area were screened for water quality priorities by reviewing Total Maximum Daily Loads (TMDLs), the State’s 303(d) list, and additional water quality data. Each identified water quality priority for a given receiving water body was categorized as a water body-pollutant combination. Water body-pollutant combinations were classified into one of three categories, in accordance with Section VI.C.5(a).ii of the Permit. Table ES-2 presents the prioritized water body-pollutant combinations within the SMB Watershed portion of the Beach Cities EWMP Area. Water body-pollutant combinations categorized below are subject to change based on future data collected as part of the Coordinated Integrated Monitoring Program (CIMP) or other monitoring program.

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Figure ES-1. Beach Cities EWMP Area

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Table ES-2. Water Body-Pollutant Combination Prioritization for the Santa Monica Bay Watershed
Category Water Body Pollutant Reason for Categorization 1: Highest
Priority
Santa Monica
Bay Beaches
Dry Weather Bacteria SMB Beaches Dry Weather Bacteria TMDL Wet Weather Bacteria SMB Beaches Wet Weather Bacteria TMDL Santa Monica
Bay
Trash/Debris SMB Debris TMDL
DDTs SMB PCBs and DDT TMDL
PCBs SMB PCBs and DDT TMDL
2: High Priority N/A None No other 303(d) listings exist for the Beach Cities portion of SMB
3: Medium
Priority N/A None
Outfall and receiving water monitoring data
are not available for the Beach Cities portion of
SMB
The Reasonable Assurance Analysis was performed on bacteria in each of the defined analysis regions (Figure ES-2), as it was the controlling pollutant within the SMB Watershed. Bacteria targets are summarized in Table ES-3.

Trash was not modeled as part of the Reasonable Assurance Analysis; instead, the Reasonable Assurance Analysis describes how the Beach Cities WMG Agencies will comply with the TMDL through their Trash Monitoring and Reporting Programs which are aimed at meeting the zero trash discharge definition in the TMDL (see Section 2.2.2 herein).

The MS4 compliance targets for dichloro-diphenyl-trichloroethanes (DDTs) and polychlorinated biphenyls (PCBs) established in the Santa Monica Bay DDT & PCB TMDL were based on the assumption that the existing stormwater pollutant loads for DDT and PCBs were equal to or lower than what was needed to protect the Santa Monica Bay from these legacy pollutants (i.e., based on data used in the TMDL, no MS4 pollutant load reduction is expected to be required to demonstrate compliance with the TMDL). Therefore, it is assumed that no reductions in DDT and PCB loading from the Beach Cities WMG MS4s are required to meet the TMDL and reasonable assurance of compliance is assumed to be demonstrated without modeling. Monitoring of these pollutants will occur under the Beach Cities CIMP. Once three years of water quality data are collected, further source assessment will be considered and the categorization and prioritization of PCBs and DDT as MS4-related pollutants of concern will be reevaluated. If the CIMP monitoring data show that Beach Cities discharges are not in compliance with the TMDL, an RAA will be conducted for these pollutants and the EWMP will be revised accordingly.

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Table ES-3. Water Quality Targets for Modeled Pollutants in the Santa Monica Bay Watershed
Water
Body Pollutant
RWL/WQBEL from
the Permit Note on Modeling Assumptions
Santa
Monica Bay
Beaches
Fecal Coliform
(modeled as surrogate
for all three fecal
indicator bacteria in
the Santa Monica Bay
Beaches Bacteria
[SMBBB] TMDL)
Allowable
Exceedance Days
per season per year
(varies by beach
Compliance
Monitoring
Location)
Used 90th percentile rain year (based on
wet days) as the critical condition.

Accounted for site-specific exceedance
rates and the number of discharge days
modeled for each Compliance
Monitoring Location.

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Figure ES-2. Analysis Regions and Compliance Monitoring Locations within the SMB Watershed portion of the Beach Cities EWMP Area

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Targets – Santa Monica Bay
Target load reductions (TLRs) represent a numerical expression of the Permit compliance metrics that can be modeled and can serve as a basis for confirming, with reasonable assurance, that implementation of the proposed BMPs will result in attainment of the applicable TMDL-based WQBELs and RWLs in the Permit for Category 1 pollutants, or the Water Quality Objectives for Category 2 and Category 3 pollutants. For bacteria, the target load reductions are expressed as Allowable Exceedance Days (AEDs) per year. TLRs for both interim and final compliance deadlines are presented for all analysis regions including both open beach and point zero compliance monitoring locations (CMLs) (Table ES-4).

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Table ES-4. TLRs for Fecal Coliform in the Santa Monica Bay Watershed Analysis
Region
Baseline Condition for the Critical
Year Allowed Condition for the Critical Year Target Load Reduction for the Critical Year6 Annual
Runoff
Average
Pollutant
Conc.5
Annual
Pollutant
Load
Annual
Runoff
Average
Pollutant
Conc.5
Annual
Pollutant
Load
Interim Target Load
Reduction
Final Target Load
Reduction
(ac-ft)
(MPN/
100mL) (1012 MPN) (ac-ft)
(MPN/
100mL) (1012 MPN)
Absolute
Load
% of
Baseline
Annual
Load
Absolute
Load
% of
Baseline
Annual
Load
(1012
MPN)
(1012
MPN)
SMB-5-011 39 15,400 7.4 39 15,400 7.4
Interim target load
reduction assessed on
a watershed-wide
basis
0 0%
SMB-O-06 90 20,700 23.0 90 20,700 23.0 0 0%
SMB-5-02 1516 28,600 534.8 1516 15,400 287.2 247.6 46.3% SMB-5-02/
SMB-5-032 123 23,000 34.9 123 23,000 34.9 0 0%
SMB-5-031 65 36,200 29.0 65 36,200 29.0 0 0%
SMB-5-03/
SMB-5-042 251 28,800 89.3 251 28,800 89.3 0 0%
SMB-5-041 51 27,200 17.1 51 27,200 17.1 0 0%
SMB-5-04/
SMB-5-052 37 17,800 8.2 37 17,800 8.2 0 0%
SMB-5-051 472 31,400 182.8 472 31,400 182.8 0 0%
SMB-5-05/
SMB-6-012 36 15,100 6.7 36 15,100 6.7 0 0%
SMB-6-013 2118 27,100 706.6 2118 15,100 394.3 312.1 44.2% BCSump3 1191 25,800 379.4 1191 13,700 201.4 178 46.9%
SMB-6-01/
SMB-6-022 621 21,200 162.5 621 21,200 162.5 0 0%
SMB-6-021,4 358 22,600 99.6 358 22,600 99.6 0 0%
SMB-6-03 206 24,500 62.2 206 24,500 62.2 0 0%
SMB-6-04 621 27,400 209.9 621 27,400 209.9 0 0%
SMB-6-051 230 32,000 90.9 230 32,000 90.9 0 0%
SMB-O-08 425 26,500 138.9 425 26,500 138.9 0 0%
SMB-6-061 19 28,000 6.7 19 28,000 6.7 0 0%
SMB
Watershed 8468 26,700 2789.9 8468 19,600 2052.1 368.9 13% 737.7 26%

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1 Anti-degradation site.
2 For the unmonitored tributary areas located in-between the CML tributary areas, TLRs were assigned from the geographically smaller of the two adjacent CML analysis regions.
3 “BCSump” was defined as a separate analysis region for modeling purposes. The baseline load for “BCSump” analysis region was combined with the baseline load of the “SMB-6-01” analysis region to equal the total baseline load contributing to the SMB-6-01 CML (“SMB-6-01+BCSump”). 4 The drainage area to Outfall SMB-O-07 is encompassed by analysis region SMB-6-02; therefore SMB-O-07 was analyzed as part of analysis region SMB-6-02.
5 The average pollutant concentration is estimated as the total pollutant load divided by total runoff volume. 6 RAA demonstration is made based on the achievement of the TLR values in terms of absolute load removed by the proposed suite of BMPs in each analysis region. The allowed conditions in terms of runoff volume and concentration are shown for informational purposes only.

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Nine CMLs were assigned zero TLRs to reflect their historic good water quality (consistent with anti-degradation-based wet weather allowable exceedance days). Although the SMBBB TMDL requires only the maintaining of beach water quality at anti-degradation compliance locations, the Beach Cities EWMP will seek to implement nonstructural and Low Impact Development (LID)- based BMPs within the SMB portion of their EWMP area; this will further protect and potentially improve water quality at these beaches and is consistent with the Jurisdictional Group 5 and 6 (J5&6) Implementation Plan (Geosyntec Consultants, 2011).

BMPs – Santa Monica Bay
EWMPs offer Permittees the opportunity to identify and implement focused strategies, control measures and BMPs to achieve applicable water quality targets (WQBELs and RWLs) and to reduce the discharge of pollutants to the maximum extent practicable. In order to demonstrate reasonable assurance, BMPs were identified and prioritized. Prioritization was based on cost (low cost BMPs were prioritized); BMP effectiveness for the pollutants of concern (BMPs that had greater treatment efficiency for the specific pollutants of concern were prioritized); and implementation feasibility as determined by the Beach Cities agencies. In general, nonstructural (e.g., programmatic) BMPs were prioritized over structural BMPs due to their lower relative cost.

The following is an overview of the types of BMPs contemplated in this EWMP within the Santa Monica Bay Watershed.

Programmatic BMPs: These source controls include a combination of BMPs such as new or enhanced pet waste controls (ordinance, signage, education/outreach, mutt mitts, etc.), Clean Bay Restaurant Program, human waste source tracking and remediation (e.g., leaking sewer investigations including implementation of each agency’s Sanitary Sewer Management Plan consistent with Statewide Waste Discharge Requirements [WDRs], etc.), enhanced street sweeping (e.g., 100% vacuum sweepers, increased frequency, posting of ‘No Parking’ signs for street sweeping, etc.), increased catch basin and storm drain cleaning, and other new or enhanced nonstructural BMPs that target the pollutants addressed in this EWMP.

Public Retrofit Incentives: These BMPs include programs directed at incentivizing the public to decrease the amount of stormwater runoff from their property, specifically via downspout disconnection programs that redirect roof runoff to vegetated or otherwise pervious areas.

Redevelopment: Beginning in 2001, redevelopment projects were required by the Permit (via the Standard Urban Stormwater Management Program [SUSMP]) to incorporate stormwater treatment BMPs into their projects if their project size exceeded specified thresholds. The 2001 MS4 Permit SUSMP redevelopment requirements were applied between 2003 (the point at which the Bacteria TMDL was implemented) and 2015 for the SMB EWMP area. Additionally, the 2012 MS4 Permit established new criteria for redevelopment projects, requiring certain sized projects to capture, retain, or infiltrate the 85th percentile design storm or the 0.75-inch design storm, whichever is greater, via the implementation of LID BMPs. These were taken into account as well.

Non-MS4 Permitted Parcels or Areas: In general, this BMP assumes that regulated parcels/areas would be in compliance with the NPDES Statewide Storm Water Permit Waste Discharge

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Requirements (WDRs) from State of California Department of Transportation (Order No. 2012- 0011-DWQ, NPDES No. CAS000003) and the California NPDES General Permit for Storm Water Discharges Associated with Industrial Activities (Industrial General Permit [IGP], Order 2014- 0057-DWQ).

Structural BMPs: Both existing and proposed regional and distributed structural BMPs are included in this EWMP to address water quality targets in the SMB Watershed. Because bacteria were identified as the controlling pollutant of concern, infiltration BMPs were prioritized as they are most effective for addressing bacteria. General design criteria for proposed structural BMPs are summarized in Table ES-5.

Table ES-5. Proposed Structural BMPs in the Santa Monica Bay Watershed Analysis
Region Project Name1 Description
Design
Storage
Volume
(cu-ft)
Tributary
Area
(acres)
SMB-5-02
Manhattan
Beach
Infiltration
Trench3
Located along the coast of Manhattan Beach, the
sub-surface trench has a potential surface area
of 2.2 ac, an average depth of 2.1 ft with a
diversion rate of 160 cfs and an infiltration rate
under the trench of 13 in/hr.
198,000 1,4752
SMB-5-02 Distributed
Green Streets
The distributed green streets, proposed to
address runoff from 5% of single family
residential, multi-family residential, and
commercial land uses, are assumed to have 6 in
of ponding, 1.5 ft of amended soil, 3 in of mulch,
and an infiltration rate of 0.15 in/hr.
205,500 66
SMB-6-01
Hermosa Beach
Infiltration
Trench
Located along the coast of Hermosa Beach, the
sub-surface trench has a potential surface area
of 0.2 ac, an average depth of 1.7 ft, a diversion
flowrate of 25 cfs, and an infiltration rate of

12.5 in/hr.
13,300 2,0002
SMB-6-01
Hermosa Beach
Greenbelt
Infiltration3
Located in Hermosa Beach, between Valley Dr.
and Ardmore Ave., the sub-surface trench has a
potential surface area of 1.5 ac, an average
depth of 5 ft, a diversion flowrate of 48 cfs, and
an assumed infiltration rate of 12 in/hr.
319,000 1,8002
SMB-6-01 Park #3
Located northwest of Blossom Lane and 190th
street, the sub-surface infiltration basin has a
potential surface area of 0.4 ac, an average
depth of 5ft , a diversion flowrate of 13 cfs, and
an infiltration rate of 1 in/hr.
87,100 1,4302
SMB-6-01 Distributed
Green Streets
The distributed green streets, proposed to
address runoff from 25% of single family
residential, multi-family residential, and
commercial land uses, are assumed to have 6 in
of ponding, 1.5 ft of amended soil, 3 in of mulch,
and an infiltration rate of 0.15 in/hr.
605,200 190
1 All projects listed in this table were modeled in the RAA and sized to collectively comply with the WQBELs and RWLs in combination with other existing and proposed structural and non-structural BMPs 2 This includes upstream BMPs and associated tributary drainage areas 3 Alternative project locations have also been identified

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Distributed green streets BMPs are proposed and were modeled as part of the Reasonable Assurance Analysis within select analysis regions, at analysis region-specific implementation levels (e.g., runoff from 14% of single family residential, multi-family residential, and commercial land uses would be treated by green streets BMPs). It should be noted that if at any time in the future, specific distributed green streets or regional/centralized BMPs are found to be infeasible for implementation, alternative BMPs or operational changes will be planned within the same subwatershed and within the same timeline, to meet an equivalent subwatershed load reduction.

In addition, if monitoring data indicate that more easily implementable, alternative BMPs can provide equivalent (or superior) load reductions, these alternative BMPs may be implemented at the discretion of the WMG Agencies. The Beach Cities WMG will provide timely notification and project details to the Regional Board in the case of any project substitutions.

Demonstration of Compliance – Santa Monica Bay
To demonstrate wet weather compliance, a Reasonable Assurance Analysis was conducted in which the following steps were taken:

1. For each analysis region, develop TLRs for 90th percentile year based on Permit requirements and LARWQCB guidance;

2. Identify structural and non-structural BMPs that were either implemented after applicable TMDL effective dates or are planned for implementation in the future:
a. Assume a load reduction for non-modeled non-structural (or programmatic) BMPs (five percent of baseline pollutant load);
b. Calculate load reductions for public incentives for retrofits on private property (e.g., downspout disconnects) and redevelopment (e.g., low impact development requirements);
c. Calculate load reductions attributable to anticipated new permit compliance activities of non-MS4 Permittees (e.g., Industrial General Permit holders and California Department of Transportation [Caltrans]); and d. Calculate load reductions for proposed regional BMPs that were identified in existing plans;

3. Compare total estimated load reduction for each analysis region with the TLRs; and

4. Meet the TLRs by backfilling the remaining load reduction with new regional or distributed green streets BMPs, and with green streets that address a certain percentage of specific developed land uses.

Results of the Reasonable Assurance Analysis for each analysis region in the SMB watershed are presented in Table ES-6 below. The values provided correspond to the load reductions attributable to the BMP types following the applicable final and interim compliance deadlines. As shown, the final TLR is met in all SMB watershed analysis regions with varying applications of non-structural and regional BMPs. The interim 50% TLR is met through a combination of nonstructural and existing regional BMPs.

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For dry weather bacteria compliance, a qualitative analysis was conducted to show compliance at each of the CMLs. Many CMLs have an effective diversion such that they are consistently operational, well maintained, and sized to effectively eliminate discharges to the surf zone during year-round dry weather days. For the remaining smaller outfalls a systematic screening conducted in 2002 demonstrated that there was no discharge to the wave wash during summer dry weather from these storm drains. Rescreening of outfalls will be conducted as part of the Non-Stormwater Screening and Monitoring in the Coordinated Integrated Monitoring Program and will include both summer dry weather and winter dry weather screening. For the CMLs in the SMB Watershed that have anti-degradation based allowed exceedance days for both winter-dry and summer-dry weather, reasonable assurance is assumed to be demonstrated through the basis that the TMDL established their allowed exceedance days based on historic conditions (i.e., no water quality improvements were necessary).

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Table ES-6. Santa Monica Bay Watershed – Fecal Coliform Reasonable Assurance Analysis Results – Interim and Final Compliance
Analysis
Region
Implementation Benefits (average load reduction as % of baseline load for critical year) TLR
Compliance
(TLR Met)?
Non-Structural
BMPs
(Non-Modeled)
Public Retrofit
Incentives +
Redevelopment
NonMS4Regional
BMPs
Distributed
BMPs
Distributed
BMP
Implementation
Level
Estimated
Load
Reduction
SMB-5-01 5% 2% 0% 0% 0% N/A 7% 0% Yes
SMB-O-06 5% 2% 0% 0% 0% N/A 7% 0% Yes
SMB-5-02 5% 4% 2% 36% 3% 5%
MFR/COM/SFR 50% 46% Yes
SMB-5-02/5-03 5% 3% 0% 0% 0% N/A 8% 0% Yes
SMB-5-03 5% 3% 0% 0% 0% N/A 8% 0% Yes
SMB-5-03/5-04 5% 4% 0% 5% 0% N/A 15% 0% Yes
SMB-5-04 5% 5% 0% 1% 1%2 N/A 12% 0% Yes
SMB-5-04/5-05 5% 4% 0% 2% 0% N/A 11% 0% Yes
SMB-5-05 5% 4% 5% 3% 0% N/A 18% 0% Yes
SMB-5-05/6-01 5% 3% 0% 2% 0% N/A 10% 0% Yes
SMB-6-01+
BCSump1 5% 3% 3% 33% 2% 25% MFR/COM/SFR 46% 45% Yes
SMB-6-01/6-02 5% 2% 4% 0% 0% N/A 11% 0% Yes
SMB-6-02 5% 3% 1% 4% 0% N/A 13% 0% Yes
SMB-6-03 5% 3% 5% 10% 0% N/A 23% 0% Yes
SMB-6-04 5% 4% 3% 0% 0% N/A 12% 0% Yes
SMB-6-05 5% 3% 6% 0% 0% N/A 15% 0% Yes
SMB-O-08 5% 2% 0% 0% 0% N/A 7% 0% Yes
SMB-6-06 5% 5% 0% 0% 0% N/A 10% 0% Yes
Final
Compliance
Deadline
(2021)
5% 3% 3% 21% 1% N/A 33% 26% Yes
Interim
Compliance
Deadline
(2018)

2.5% 0.8% 1.5% 9.6% 0% N/A 14.4% 13% Yes
1 “BCSump” was defined as a separate analysis region for modeling purposes. The baseline load for “BCSump” analysis region was combined with the baseline load of the “SMB-6-01” analysis region to equal the total baseline load contributing to the SMB-6-01 CML (“SMB-6-01+BCSump”). 2 Distributed green street BMP load reduction in SMB-5-04 is a result of the existing filter/infiltration boxes retrofitted on the east side of Hermosa Avenue in the City of Hermosa Beach.

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Schedule – Santa Monica Bay
In order to meet the compliance deadlines for the water body-pollutant combinations discussed above based on load reduction projections in the Reasonable Assurance Analysis, the proposed structural BMPs within the SMB Watershed would be implemented as described in Figure ES-3.

Figure ES-3. Proposed Project Sequencing in the Santa Monica Bay Watershed COLOR
KEY Funding Phase Design Phase Construction/ Installation Phase BMP Location/Name
Timeline
2015201620172018201920202021
Santa Monica Bay Watershed
Catch basin retrofits for trash
Manhattan Beach Infiltration
Trench1
Manhattan Beach Green streets
application in SMB-5-02
Hermosa Beach Greenbelt
Infiltration1
Hermosa Beach Infiltration Trench
Redondo Beach Park #3
Green streets application in SMB-6-
01 for All Cities
1 Alternative project locations have also been identified

DOMINGUEZ CHANNEL WATERSHED
Within the Dominguez Channel Watershed, water body-pollutant combinations were classified into one of three categories, in accordance with Section VI.C.5(a).ii of the Permit. Table ES-7 presents the prioritized water body-pollutant combinations within the Dominguez Channel Watershed portion of the Beach Cities EWMP Area. Water body-pollutant combinations categorized below are subject to change based on future data collected as part of the CIMP or other monitoring program.

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Table ES-7. Water Body-Pollutant Prioritization for the Dominguez Channel Watershed Category Water Body Pollutant Reason for Categorization 1:

Highest
Priority
Dominguez
Channel (including
Torrance Lateral) 1
Toxicity Dominguez Channel Toxics TMDL
Total Copper Dominguez Channel Toxics TMDL
Total Lead Dominguez Channel Toxics TMDL
Total Zinc Dominguez Channel Toxics TMDL
Dominguez
Channel Estuary
Total Copper Dominguez Channel Toxics TMDL
Total Lead Dominguez Channel Toxics TMDL
Total Zinc Dominguez Channel Toxics TMDL
Cadmium Dominguez Channel Toxics TMDL
DDT Dominguez Channel Toxics TMDL
Total PAHs Dominguez Channel Toxics TMDL
PCBs Dominguez Channel Toxics TMDL
2: High
Priority
Dominguez
Channel (including
Torrance Lateral)
Indicator
Bacteria 303(d) List
Ammonia 303(d) List
Dominguez
Channel Estuary
Indicator
Bacteria 303(d) List
Ammonia 303(d) List
3:

Medium
Priority
Dominguez
Channel (including
Torrance Lateral)
Cyanide
Historic exceedances of the California Toxics Rule
(CTR) continuous concentration water quality
objective (5.2 ug/L)
pH Historic exceedance of the Basin Plan Objective (6.5 –

8.5)
Selenium Historic exceedances of the CTR continuous
concentration water quality objective (5.0 ug/L)
Mercury Historic exceedances of the CTR human health
criterion for organisms only (0.051 ug/L)
Cadmium Historic exceedances of the CTR continuous
concentration water quality objective (2.2 ug/L)
Dominguez
Channel Estuary
Arsenic
Historic exceedances of the Effects Range-Low (ERL)
proposed sediment quality guidelines from the
National Status and Trends database (8.2 mg/kg
sediment)
Chromium
Historic exceedances of the ERL proposed sediment
quality guidelines from the National Status and
Trends database (81 mg/kg sediment)
Silver Historic exceedances of the CTR continuous
saltwater objective (1.9 ug/L)
Nickel
Historic exceedances of the CTR maximum saltwater
objective (74 ug/L) and the CTR continuous
saltwater objective (8.2 ug/L)
Mercury
Historic exceedances of the ERL proposed sediment
quality guidelines from the National Status and
Trends database (0.15 mg/kg sediment) and the CTR
human health criterion for organisms only (0.051
ug/L)
Thallium
Historic exceedances of the ERL proposed sediment
quality guidelines from the National Status and
Trends database (6.3 ug/L sediment)

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For the purposes of the wet weather Reasonable Assurance Analysis, the EWMP area directly draining to Dominguez Channel was combined into a single analysis region to establish TLRs and into two analysis regions, one including the portion of the Cities of Redondo Beach and Manhattan Beach (Dominguez Channel – Redondo Beach/Manhattan Beach [DC–RB/MB]) and one including the portion of the City of Torrance (DC – Torrance), to evaluate the performance of BMPs. For the purposes of the dry weather Reasonable Assurance Analysis for which bacteria are the only water body-pollutant combination, the EWMP area draining to Dominguez Channel was combined into the same single analysis region. The Dominguez Channel watershed analysis regions are shown in Figure ES-4.

The wet weather Reasonable Assurance Analysis was performed on copper, lead, zinc, and bacteria (fecal coliform) within the Dominguez Channel Watershed. Water quality targets were identified for Dominguez Channel Watershed in the same manner as in SMB Watershed. According to the Dominguez Channel WMA EWMP (DC WMG, 2015), relationships between TSS and historical organics were evaluated to determine if TSS could be used as a surrogate for historical organics. As there were significant non-detects in the available water quality data, a relationship between historic organics and TSS could not be established in the available Dominguez Channel monitoring data. Other studies have shown that relationship between TSS and historical organics can exist; however, the water quality depends on the storm event, soil disturbance, and other factors. It was assumed that if water column pollutant targets were met in Dominguez Channel, the targets would also be met downstream in the Dominguez Channel Estuary, which is the receiving water to Dominguez Channel. Sediment-borne pollutants would also be reduced by the same BMPs that are being used to address the water column pollutants. For these reasons, it was not necessary to perform a separate Reasonable Assurance Analysis for the Dominguez Channel Estuary. If monitoring data show that Dominguez Channel discharges are not meeting sediment objectives, a Reasonable Assurance Analysis will be conducted for sediment and the EWMP will be revised accordingly.

For metals, the waste load allocation (WLA) assigned to MS4 discharges, as shown in Table ES-8, is a mass-based allocation based on the freshwater targets for Dominguez Channel and Torrance Lateral (using ambient hardness at the time of sampling) multiplied by the daily volume and is shared amongst all MS4 Permittees that discharge to the freshwater portion of Dominguez Channel and Torrance Lateral. The water quality targets for prioritized water body-pollutant combinations are summarized in Table ES-8.

Table ES-8. Water Quality Targets for the Dominguez Channel Watershed Water Body Pollutant
RWL/WQBEL from the Permit
or Assumed Based on Other
Similar Los Angeles Region
TMDLs1
Approach for Applying the Critical
Period
Dominguez
Channel
Fecal
Coliform
19% allowed exceedance of the
REC-1 water quality objective,
(400 MPN/100mL) on non-high
flow suspension days
90th percentile year (based on wet
days) was used as the critical
condition. Allowable number of wet
weather exceedance days for the
critical year was set to 19% of nonhigh flow suspension wet days, rounding down.

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Water Body Pollutant
RWL/WQBEL from the Permit
or Assumed Based on Other
Similar Los Angeles Region
TMDLs1
Approach for Applying the Critical
Period
Total
Copper
WQBEL=9.7 ug/L
Waste load allocation (WLA)=
Concentration*Daily Volume
90th percentile daily load during wet
weather was used as the critical
condition. This calendar day was
identified for each metal by ranking
daily loads for metal wet days
between 2003 and 2012.

Total Lead
WQBEL=42.7 ug/L
WLA= Concentration*Daily
Volume
Total Zinc WQBEL=69.7 ug/L WLA=
Concentration*Daily Volume
1 MS4 Permittees may demonstrate compliance with the freshwater metals allocations for Dominguez Channel and Torrance Lateral via any one of three different means:
a. Final allocations are met.
b. CTR total metals criteria are met instream.
c. CTR total metals criteria are met in the discharge.

Although toxicity was identified as a Category 1 water body-pollutant combination, it was not modeled for Dominguez Channel and the Torrance Lateral since it is not a wet weather parameter that can be modeled using currently available Reasonable Assurance Analysis tools for the Los Angeles Region. Instead, the Reasonable Assurance Analysis qualitatively describes how the Beach Cities WMG Agencies will comply with the TMDL WQBELs. Toxicity will continue to be monitored under the Beach Cities’ CIMP. Although ammonia was identified as a Category 2 water bodypollutant combination (Table ES-7), monitoring data since 2003 show that all water quality samples at monitoring locations S28 and TS19 meet the freshwater Basin Plan Objective for ammonia, and as a result, ammonia was not modeled as part of the Beach Cities’ Reasonable Assurance Analysis. Similarly, the Category 3 water body-pollutant combinations cyanide, pH, selenium, mercury, and cadmium, all within the Torrance Lateral, were not modeled either due to a lack of demonstrated MS4 linkage or due to data limitations. These Category 2 and 3 parameters will also be monitored under the Beach Cities’ CIMP and if future monitoring data suggest that the Beach Cities’ MS4s may cause or contribute to exceedances of these pollutants in the receiving water, the EWMP will be revised to address these pollutants.

Dominguez Channel is also 303(d)-listed for diazinon, although data are not available on the SWRCB’s website since this listing was made prior to 2006. However, as the Dominguez Channel Toxics TMDL staff report states,the USEPA banned diazinon on December 31, 2005. The Dominguez Channel Toxics TMDL staff report (Section 2.6.1) states, "Whereas elevated diazinon levels had been observed concurrently with toxicity in 2002-2005 wet weather samples and therefore diazinon was presumed to be contributing to adverse toxicity results; post-2005 results show no diazinon concentrations above the freshwater guideline. Therefore, it is appropriate to develop freshwater metals and toxicity TMDLs for wet weather; however, the more recent toxicity results are not attributable to diazinon and therefore no diazinon TMDLs have been developed for Dominguez Channel." Dominguez Channel and Torrance Lateral data from 2006-2013, which includes 85 total samples between the two monitoring sites, show no exceedances of the chronic diazinon criteria established by the California Department of Fish and Game (0.10 ug/L). Due to the fact that monitoring data since 2006 show that all samples at S28 and TS19 meet the applicable water quality criteria for diazinon, diazinon could reasonably be removed from the State’s 303(d)

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list for Dominguez Channel and therefore is not included as a Category 2 pollutant for Dominguez Channel (including Torrance Lateral).

Figure ES-4. Analysis Regions within the Dominguez Channel Watershed portion of the Beach Cities EWMP Area

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Targets – Dominguez Channel
As discussed previously, TLRs represent a numerical expression of the Permit compliance metrics (e.g., allowed mass per day for metals for wet weather and allowable exceedance days per year for bacteria) that can be modeled and can serve as a basis for confirming, with reasonable assurance, that implementation of the proposed BMPs will result in attainment of the applicable TMDL-based WQBELs and RWLs in the Permit for Category 1 pollutants, or the Water Quality Objectives for Category 2 and Category 3 pollutants. TLRs were developed for the single combined analysis region (Table ES-9).

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Table ES-9. TLRs and Baseline Conditions for Pollutants in the Dominguez Channel Watershed Pollutant
Compliance
Deadline
Baseline Data for Critical Condition
Allowable Discharge for Critical
Condition
Interim Target Load
Reduction[4]
Final Target Load
Reduction[4]
Runoff
Volume
Pollutant
Conc.[3]
Pollutant
Load
Runoff
Volume
Pollutant
Conc. [3]
Pollutant
Load
Absolute
Load
% of
Baseline
Load
Absolute
Load
% of
Baseline
Load
Copper 2032 301 acft/day 25.8 ug/L 21 lb/day 301 acft/day 9.7ug/L 8 lb/day N/A[1]
13 lb/day 62%
Lead 2032 275 acft/day 11.6 ug/L 8.7 lb/day 275 acft/day 42.7 ug/L 32 lb/day 0 lb/day 0% Zinc 2032 291 acft/day 290.2 ug/L 230 lb/day 291 acft/day 69.7 ug/L 55 lb/day 175 lb/day 76%
Fecal
coliform
2022[2] 6,048 acft/year
20,080
MPN/100
mL
1,498 *1012
MPN/yr
6,048 acft/year18,413
MPN/100mL
1,373*1012
MPN/yr
124*1012
MPN/yr 8.3% - -
2027[2] 6,048 acft/year
20,080
MPN/100
mL
1,498 *1012
MPN/yr
6,048 acft/year16,667
MPN/100mL
1,243*1012
MPN/yr
255*1012
MPN/yr 17% - -
2032[2] 6,048 acft/year
20,080
MPN/100
mL
1,498 *1012
MPN/yr
6,048 acft/year13,454
MPN/100 mL
1,004*1012
MPN/yr - - 493*1012MPN/yr 33%
1 The interim deadline for Dominguez Channel Toxic TMDL was March 23, 2012. Hence the interim target load reduction is not applicable since this date has passed.

2 Proposed, non-TMDL compliance schedule.
3 Fecal coliform concentrations are estimated as the total annual load divided by the total annual runoff volume. The pollutant concentrations presented for the Dominguez Channel Toxics TMDL are a direct output from the LSPC model used for the RAA. 4 RAA demonstration is made based on the achievement of the TLR values in terms of absolute load removed by the proposed suite of BMPs in each analysis region. The allowed conditions in terms of runoff volume and concentration are shown for informational purposes only.

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BMPs – Dominguez Channel
Both existing and proposed regional and distributed BMPs are included in this EWMP to address water quality targets in the Dominguez Channel Watershed. Distributed green streets BMPs are proposed and were modeled as part of the Reasonable Assurance Analysis within the DC-RB/MB analysis region, at an implementation level of 14% (i.e., runoff from 14% of single family residential, multi-family residential, commercial, and industrial land uses would be treated by green streets BMPs). General design criteria for proposed structural BMPs are summarized in Table ES-10.

Table ES-10. Proposed Structural BMPs in the Dominguez Channel Watershed Analysis
Region Project Name1 Description
Design
Storage
Volume
(cu-ft)
Tributary
Area
(acres)
DC –
MB/RB
Powerline
Easement
Infiltration*
Located along powerline easements and/or
adjacent to Marine Avenue and Manhattan
Beach Boulevard, the sub-surface biofilter
has a potential surface area of 7.2 ac, an
average depth of 5 ft, a diversion flowrate of
132 cfs, and a negligible infiltration rate.

N/A
(Flowthrough
BMP)
1,500
DC –
MB/RB
Artesia Blvd.
and Hawthorne
Blvd. Filtration
Located near the intersection of Artesia Blvd.
and Hawthorne Blvd., the sub-surface
biofilter has a potential surface area of 1 ac,
an average depth of 5 ft, a diversion flowrate
of 13.6 cfs, and a negligible infiltration rate.

N/A
(Flowthrough
BMP)
130
DCMB/RB
Distributed
Green Streets
BMPs
The distributed green streets (to address
runoff from 14% of single family residential,
multi-family residential, commercial, and
industrial land uses) are assumed to have 6
in of ponding, 1.5 ft of amended soil, 3 in of
mulch, and an infiltration rate of 0.15 in/hr.
636,300 200
DCTorranceCatch Basin
Inlet Filters
The City of Torrance plans to retrofit catch
basins with inlet filters. N/A 5,760
1 All projects listed in this table (except for the catch basin inlet filters in DC-Torrance) were modeled in the RAA and sized to collectively comply with the WQBELs and RWLs in combination with other existing and proposed structural and non-structural BMPs. Within the DC-Torrance analysis region, catch basin inlet filters are assumed to achieve WQBEL/RWL compliance based on a review of literature/studies on their performance. The total load reduction from inlet filters will be evaluated in the future through CIMP monitoring, as part of the EWMP adaptive management process. At that time, the catch basin BMPs will be modified, with additional filters installed as necessary and additional structural/non-structural BMPs proposed as needed to meet the TLRs required to achieve water quality objectives by the compliance deadlines.
*Alternative project location has also been identified
It should be noted that if at any time specific distributed green streets or regional/centralized BMPs are found to be infeasible for implementation, or new innovative BMPs are developed, alternative BMPs or operational changes will be planned within the same analysis region and within the same timeline, to meet an equivalent analysis region load reduction. The performance of the proposed catch basin inlet filters within the City of Torrance will also be evaluated as potential alternatives to the proposed structural BMPs within the Cities of Redondo Beach and Manhattan Beach. The

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Beach Cities WMG will provide timely notification and project details to the Regional Board in the case of any project substitutions.

Demonstration of Compliance – Dominguez Channel
To demonstrate wet weather compliance, the Reasonable Assurance Analysis was performed according to the following steps:

1. For each analysis region, develop TLRs for the critical condition (90th percentile year for bacteria and 90th percentile load day for metals) based on Permit requirements and LARWQCB guidance;

2. Identify structural and non-structural BMPs that were either implemented after applicable TMDL effective dates or are planned for implementation in the future:
a. Assume a load reduction for non-modeled non-structural (or programmatic) BMPs (five percent of baseline pollutant load);
b. Calculate load reductions for public incentives for private retrofit (e.g., downspout disconnects) and redevelopment;
c. Calculate load reductions attributable to anticipated new permit compliance activities of non-MS4 entities (e.g., Industrial General Permit holders and Caltrans); and
d. Calculate load reductions for proposed regional BMPs that were identified in existing plans;

3. Compare total estimated load reduction for each analysis region with the TLRs; and

4. Meet the TLRs by backfilling the remaining load reduction with new regional or distributed green streets BMPs, with green streets modeled by assuming treatment of runoff from a percentage of specific developed land uses. Within the DC-Torrance analysis region, an estimated load reduction attributable to distributed catch basin inlet filters was derived from a review of literature/studies on their performance (Appendix B). If the estimated performance is supported by future monitoring data, these filters may be used as alternative BMPs in other portions of the Dominguez Channel Watershed.

Results of the wet weather Reasonable Assurance Analysis for each analysis region are presented in Table ES-11 below. The values provided correspond to the load reductions attributable to the BMP types following the applicable compliance deadline. As shown, the TLRs are predicted to be met in the DC-RB/MB analysis region for metals and fecal coliforms with varying applications of non-structural and regional BMPs as described previously. Within the DC-Torrance analysis region, the TLRs will be met through implementation of catch basin inlet filters as needed. Monitoring and subsequent adaptive management will be employed to evaluate the achieved load reductions prior to each of the compliance deadlines, installing additional filters as needed until compliance is achieved for every applicable WQBEL or RWL.

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For dry weather, bacteria is the only applicable pollutant in the Dominguez Channel Watershed, and it is a Category 2 water body-pollutant combination (i.e., 303(d)-listed but not currently subject to a TMDL).

The City of Torrance’s dry weather load reduction strategy will focus on non-structural source control and pollution prevention measures that are designed to reduce the amount of pollutants and understand the effect of pollutants entering runoff though education, enforcement and behavioral modification programs.

Within the Cities of Redondo Beach and Manhattan Beach, the implementation of the two regional BMPs at both outlets from the DC-RB/MB analysis region to address wet weather pollutants will control dry weather flows by capturing the small flows in the pre-treatment volume and either retaining them or treating them in the media filter.

In addition, each of the EWMP WMG cities has water conservation regulations which will reduce dry weather runoff at its source. Collectively, by controlling dry weather MS4 flows prior to entering Dominguez Channel using the proposed suite of BMPs, bacteria will be addressed. If necessary, the EWMP Group agencies retain the option of installing low flow diversions sized to effectively eliminate discharges to the receiving water year-round dry weather days. Therefore, reasonable assurance of meeting the applicable RWLs was demonstrated in this EWMP through a qualitative assessment of the proposed BMPs and their overall approach of eliminating or substantially reducing MS4 discharges during dry weather.

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Table ES-11. Dominguez Channel Watershed – Reasonable Assurance Analysis Results – Interim and Final Compliance Pollutant Date
Implementation Benefits (average load reduction as % of baseline for the critical condition1) TLR
Compliance
(TLR Met)?
Non-Structural
BMPs
(Non-Modeled)
Public Retrofit
Incentives +
Redevelopment
NonMS4Regional
BMPs
Distributed
BMPs
Distributed
BMP
Implementation
Level
Estimated
Load
Reduction
Analysis Region DC-RB/MB
Zinc 2032
(Final) 5% 9% 6% 39% 20% 14% SFR, MFR,

COM, IND
79% 76% Yes
Copper 2032
(Final) 24%2 0% 5% 30% 26% 85% 62% Yes
Fecal
coliform
2022
(Interim) 2.1% 1.5% 0.7% 0% 4.1% 3% SFR, MFR, COM, IND 8.4% 8.3% Yes 2027
(Interim) 3.5% 2.4% 1.3% 0% 10% 7% SFR, MFR, COM, IND 17% 17% Yes 2032
(Final) 5% 3.2% 1.8% 45% 20% 14% SFR, MFR, COM, IND 74% 33% Yes Analysis Region DC-Torrance
Zinc 2032
(Final) 5% 0% 0% 0% 75% per filter Catch basin inlet filters See note 3 76% See note 3 Copper 2032
(Final) 14%2 0% 0% 0% 75% per filter Catch basin inlet filters See note 3 62% See note 3 Fecal
coliform
2022
(Interim) 2.1% 0% 0% 0% 33% per filter Catch basin inlet filters See note 3 8.3% See note 3 2027
(Interim) 3.5% 0% 0% 0% 33% per filter Catch basin inlet filters See note 3 17% See note 3 2032
(Final) 5% 0% 0% 0% 33% per filter Catch basin inlet filters See note 3 33% See note 3 1 The critical condition is TMDL year 1995 for fecal coliform, 11/30/2007 for copper, 2/5/2010 for lead, and 2/26/2006 for zinc. 2 Load reduction attributable to copper brake pad phase-out, after accounting for other BMPs, up to 55%. 3 Load reduction sum cannot be estimated at this time. The individual load reduction for each inlet filter’s drainage area is shown under the “Distributed BMPs” column. Initially, 200 of 643 catch basins are planned to be retrofitted in high priority catchments. The total load reduction from inlet filters will be evaluated in the future through CIMP monitoring, as part of the EWMP adaptive management process. At that time, the catch basin BMPs will be modified, with additional filters installed as necessary and additional structural/non-structural BMPs proposed as needed to meet the TLRs required to achieve water quality objectives by the compliance deadlines.

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Schedule – Dominguez Channel
In order to meet the compliance deadlines for the water body-pollutant combinations based on load reduction projections in the Reasonable Assurance Analysis, the proposed structural BMPs within the Dominguez Channel Watershed would be implemented per the timeline provided in Figure ES-5. Project construction is proposed to be complete with project start-up beginning in 2020, at which point load reduction credit begins in the Reasonable Assurance Analysis.

Figure ES-5. Project Sequencing in the Dominguez Channel Watershed COLOR
KEY Funding Phase Design Phase Construction/ Installation Phase BMP Location/Name
Timeline
201820192020202120222023202420252026202720282029203020312032 Dominguez Channel Watershed
Catch basin inlet
filters in DC-Torrance Green Streets (Redondo Beach and Manhattan Beach) Treatment
of 3% of
Land Uses
Treatment
of
Additional
4% of Land
Uses

Treatment
of
Additional
7% of Land
Uses

Redondo Beach
Powerline Easement
Filtration1,2
Artesia Boulevard and
Hawthorne Boulevard
Filtration2 in Redondo
Beach
1Alternative project locations have also been identified. 2Current regional BMP project sequencing in Dominguez Channel helps achieve dry weather bacteria TMDL compliance. If compliance is met through other means, regional BMP scheduling in Dominguez Channel may be pushed back so that regional projects are instead complete by March 2032.

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COMPLIANCE SCHEDULE
Table ES-12 summarizes the existing and proposed implementation actions and dates within the Santa Monica Bay and Dominguez Channel Watersheds, for each identified water body-pollutant combination. The compliance schedule for Category 1 water body-pollutant combinations is consistent with the associated TMDLs. The compliance schedule for the Category 2 water bodypollutant combinations has been selected to achieve the proposed wet and dry weather bacteria milestones, with implementation actions not exceeding one year, in accordance with the Permit (Section ii(5)9B). As described in Table ES-12, the compliance schedule for the Category 3 water body-pollutant combinations will be dependent on the results of the CIMP.

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Table ES-12. Compliance Schedule for the Santa Monica Bay and Dominguez Channel Watersheds Category Watershed Pollutant(s)
Wet/Dry
Weather Date Implementation Action
1: Highest
Priority
Dominguez
Channel
and
Dominguez
Channel
Estuary
Toxicity1
Total
Copper1,2
Total Lead1,2
Total Zinc1,2
Cadmium2
Wet/Dry Current4 Interim: Comply with the interim water quality-based effluent limitations as listed in the TMDL3
March 2032
Final: Comply with the final water quality-based effluent limitations as listed in the TMDL3
Santa
Monica Bay
Bacteria Dry July 2006 Final: Summer-dry single sample Allowable Exceedance Days (AED) met; compliance is currently in effect and attained through diversions and nonstructural BMPs.

November
2009
Final: Winter-Dry period Single Sample AED met; compliance is currently in effect and attained through diversions and non-structural BMPs.

Wet July 2018 Interim: 50% single sample ED reduction
July 2021 Final: Geometric Mean [GM] targets met
Final: Single sample AED targets met
Trash/Debris N/A March 2016 Interim: 20% load reduction met through implementation of trash excluders
March 2017 Interim: 40% load reduction met through implementation of trash excluders
August 2018 Interim (Cities of Hermosa Beach and Redondo Beach): Determination of compliance strategy for installing full capture trash systems March 2019 Interim (Cities of Hermosa Beach and Redondo Beach): Installation of full capture trash systems serving 50% of the MS4 drainage area to Santa Monica Bay outside of Regional EWMP BMPs
August 2019 Interim (City of Manhattan Beach): Determination of compliance strategy for installing full capture trash systems.

March 2020
Interim (City of Manhattan Beach): Installation of full capture trash systems serving 50% of the MS4 drainage area to Santa Monica Bay outside of Regional EWMP BMPs
Final (Cities of Hermosa Beach and Redondo Beach): 100% reduction in trash from baseline through the installation of full capture trash systems serving MS4 drainage area to Santa Monica Bay.

March 2023 Final (City of Manhattan Beach): 100% reduction in trash from baseline through the installation of full capture trash systems serving MS4 drainage area to Santa Monica Bay.

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Category Watershed Pollutant(s)
Wet/Dry
Weather Date Implementation Action
DDTs N/A N/A Since the TMDL effectively implements an anti-degradation approach (i.e., historic low MS4 concentrations or loads must be kept the same or lower), and the Beach Cities EWMP Agencies are currently presumed to be achieving the WLAs (thus negating the need for Reasonable Assurance Analysis), no compliance schedule is proposed.

PCBs N/A
N/A
2: High
Priority
Dominguez
Channel and
Dominguez
Channel
Estuary
Bacteria Dry December 2023 Interim: 50% load reduction
December
20255
Final: 100% compliance may be demonstrated by the Permittee in one of three ways:

1. Meeting the allowed exceedance days (5 days during the dry weather period); or

2. Meet the allowed exceedance percentage (1.6% during a dry weather period) within the total drainage area served by the MS4.

3. Diversions are in place such that they are consistently operational, well maintained, and sized to effectively eliminate discharges to the receiving water year-round dry weather days.

Wet December 2016 Provide documentation supporting minimum control measure (MCM) enhancements implemented over the past year6
December 2017 Provide documentation supporting MCM enhancements implemented over the past year6
December 2018 Identify planned green streets locations to treat runoff from 3% of SFR, MFR, COM, and IND land uses in cities of Redondo Beach and Manhattan Beach.

December 2019 City Council approval of Plans & Specifications for green streets to treat runoff from 3% of SFR, MFR, COM, and IND land uses in cities of Redondo Beach and Manhattan Beach. Begin installation of catch basin inlet filters in the DC-Torrance analysis region.

December 2020 Develop concept reports for regional BMPs in the cities of Redondo Beach and Manhattan Beach. Begin construction on green streets to treat runoff from 3% of SFR, MFR, COM, and IND land uses in cities of Redondo Beach and Manhattan Beach.

December 2021 Submit grant application for any one of the proposed regional projects in the cities of Redondo Beach and Manhattan Beach.

December 2022 Interim Milestone: 25% of target load reduction

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Category Watershed Pollutant(s)
Wet/Dry
Weather Date Implementation Action
December 2023 Identify planned green streets locations to treat runoff from an additional 4% (7% total) of SFR, MFR, COM, and IND land uses in cities of Redondo Beach and Manhattan Beach.

December 2024 Begin construction on planned green streets to treat runoff from an additional 4% (7% total) of SFR, MFR, COM, and IND land uses in cities of Redondo Beach and Manhattan Beach. Continue installation of catch basin inlet filters in the DC-Torrance analysis region.

December 2025 Release Request for Proposals for regional BMP designs in Redondo Beach and/or Manhattan Beach
December 2026 Complete construction on planned green streets to treat runoff from an additional 4% (7% total) of SFR, MFR, COM, and IND land uses in cities of Redondo Beach and Manhattan Beach.

December 2027 Interim Milestone: 50% of target load reduction December 2028 Produce regional BMP design reports; identify locations for green streets implementation to treat runoff from an additional 7% (14% total) of SFR, MFR, COM, and IND land uses in the cities of Redondo Beach and Manhattan Beach.

December 2029 Begin regional BMP permitting process for project in Redondo Beach or Manhattan Beach.

December 2030 Begin construction on planned green streets to treat runoff from an additional 7% (14% total) of SFR, MFR, COM, and IND land uses in the cities of Redondo Beach and Manhattan Beach.

December
20317
Begin regional BMP construction of project in Redondo Beach or Manhattan Beach.

March 20328 Final Milestone: 100% compliance may be demonstrated by the Permittee in one of three ways:

1. Meeting the allowed exceedance days (10 days during a wet weather period, plus high flow suspension days)

2. Meeting the target load reduction (33%); or

3. Meeting the allowed exceedance percentage (19% during a wet weather period) within the total drainage area served by the MS4.

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Category Watershed Pollutant(s)
Wet/Dry
Weather Date Implementation Action
3:

Medium
Priority9
Dominguez
Channel
and
Dominguez
Channel
Estuary
Cyanide
pH
Selenium
Mercury
Cadmium
Arsenic
Chromium
Silver
Nickel
Thallium
N/A March 20328 Final: Comply with the applicable water quality standards as listed in Table ES-7.

As required by the Permit, monitoring for these pollutants will occur under the CIMP. If monitoring data suggest that the Beach Cities Agencies’ MS4s may cause or contribute to exceedances of these pollutants in the receiving water,10 these contributions will be addressed through modifications to the EWMP as a part of the adaptive management process, as described in Permit section VI.C.2.a.iii.
1 Toxicity, copper, lead, and zinc are listed as Category 1 wet weather pollutants in Dominguez Channel. 2 Copper, lead, zinc, and cadmium are listed as Category 1 pollutants in Dominguez Channel Estuary with annual average WQBELs that apply to both wet and dry weather. 3 Dominguez Channel Estuary WQBELs for total copper, lead, zinc, and cadmium are addressed by the implementation actions taken for Dominguez Channel wet weather WQBELs. 4 According to monitoring data at Dominguez Channel Mass Emission Station S28, the copper, lead, and zinc exceedance rates of the interim WQBELs are 9%, 3% 10% respectively, based on qualified sampling events between 2002 and 2013. At the Torrance Lateral Mass Emission Station TS19, the copper, lead, and zinc exceedance rates of the interim WQBELs are 5%, 0%, and 8% respectively. These monitoring locations receive flow contributions from the Beach Cities WMG, as well as other WMGs. CIMP monitoring and subsequent adaptive management will evaluate if the Beach Cities WMG are exceeding the interim Category 1 WQBELs and evaluate compliance with the Dominguez Channel Toxics TMDL. 5 The proposed compliance schedule for dry weather bacteria is the minimum time expected to be necessary for the agencies to plan, design, permit, construct, monitor, and adaptively manage the proposed dry weather BMPs, and is also consistent with the 10-year MS4 compliance schedule for dry weather from the TMDL for indicator bacteria in the San Gabriel River, Estuary and Tributaries, adopted by the LARWQCB in 2015 (Water Quality Control Plan, Attachment A to Resolution No. R15-005, adopted by the RWQCB in 2015). 6 Proposed milestones for MCM enhancement implementation are detailed in Table 2-8. 7 If regional BMPs are deemed necessary for dry weather compliance, their construction dates will be moved up to meet the dry weather deadlines. 8 The proposed compliance schedule for wet weather bacteria and all Category 3 pollutants was selected to be consistent with the Dominguez Channel and Greater Los Angeles and Long Beach Harbor Waters Toxic Pollutants TMDL (Dominguez Channel Toxics TMDL) (RWQCB, 2011). This compliance schedule is the minimum time expected to be necessary for the agencies to plan, design, permit, construct, monitor, and adaptively manage the proposed wet weather BMPs. 9 Cyanide, pH, selenium, mercury, and cadmium are Category 3 pollutants in Dominguez Channel. Arsenic, chromium, silver, nickel, mercury, and thallium are Category 3 pollutants in Dominguez Channel Estuary. 10 This will be assumed to be the case if monitoring data show that outfall concentrations and receiving water concentrations are in excess of the applicable water quality criteria for the same monitoring event.

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PLANNING LEVEL COST OPINION
Planning-level cost opinions associated with implementation of the proposed structural best management practices within the Beach Cities WMG area are provided based on results from the Reasonable Assurance Analysis for the Beach Cities EWMP. Cost opinions are presented as an aid for decision makers, and contain considerable uncertainties. Given the iterative and adaptive nature of the EWMP and the many variables associated with the projects, the budget forecasts are orderof magnitude opinions, and are subject to change based on site-specific BMP feasibility assessment findings, preliminary and final BMP designs and landscaping, BMP effectiveness assessments, results of outfall and receiving water monitoring, and special studies such as those that might result in site specific objectives which could modify water quality objectives or TMDL Waste Load Allocations for a specific water body-pollutant combination.

EWMP planning-level cost opinions were developed for the proposed structural BMPs in addition to programmatic costs. Costs approximated for structural BMPs include “hard” costs for tangible assets and “soft” costs, which include considerations such as design and permitting. Table ES-13 summarizes the total 20-year life-cycle costs for each proposed structural BMP, which are composed of the cost to construct or implement each structural BMP plus the associated annual O&M costs over 20 years. In order to account for possible variations in BMP design, BMP configurations, and site-specific constraints, as well as for uncertainties in available BMP unit costs from literature or estimated BMP unit costs, a range of costs is presented. These cost opinions are provided for information only, and it is recognized that should monitoring information demonstrate that alternative, less-expensive BMPs are equally (or superior) to those described herein, that these alternative BMPs may be implemented at the discretion of the WMG agencies. Not included in these costs are the annual monitoring costs for implementing the CIMP or the costs associated with implementing baseline and enhanced MCMs.

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Table ES-13. Cost Opinion for Proposed Structural BMPs in Santa Monica Bay and Dominguez Channel Watersheds Watershed/
Analysis Region Location of BMP Project Name
Construction Cost
Range Annual O&M Range
Total 20-Year LifeCycle1 Range
Low High Low High Low High
Santa Monica Bay
Watershed
SMB-5-02,
Alternative 1
Manhattan Beach Manhattan Beach Infiltration Trench2 $3.7M $6.8M $140K $190K $6.5M $11M Manhattan Beach Distributed Green Streets $2.4M $6.5M $110K $220K $4.6M $11M SMB-5-02 Alternative 1 Combined Costs $6.1M $13M $250K $410K $11M $22M SMB-6-01
Hermosa Beach Hermosa Beach Infiltration Trench $500K $1.1M $18K $32K $860K $1.7M Hermosa Beach Hermosa Beach Greenbelt Infiltration2 $5.5M $8.0M $81K $90K $7.1M $9.8M Redondo Beach Park #3 $1.9M $3.0M $28K $33K $2.5M $3.7M Hermosa Beach Distributed Green Streets $7.0M $19M $310K $640K $13M $32M SMB-6-01 Combined Costs $15M $31M $440K $800K $23M $47M All Analysis
Regions
Hermosa Beach Trash exclusion devices $160K $430K $50K $64K $1.1M $1.7M Redondo Beach Trash exclusion devices $1.1M $3.1M $360K $460K $8.3M $12M Manhattan Beach Trash exclusion devices $590K $1.7M $210K $270K $4.8M $7.1M Combined Costs in Santa Monica Bay Watershed $23M $50M $1.3M $2.0M $49M $90M Dominguez
Channel
Watershed

DC-RB/MB
Redondo Beach Powerline Easement Infiltration2 $11M $16M $160K $180K $14M $20M Redondo Beach Artesia Blvd Infiltration $2.0M $3.1M $30K $35K $2.6M $3.8M Redondo Beach +
Manhattan Beach Distributed Green Streets $7.4M $20M $330K $670K $14M $33M DC-RB/MB Combined Costs $20M $39M $520K $890K $31M $57M DC-Torrance Torrance Catch basin inlet filters $240K $360k $130K $170k $2.8M $3.7M DC-Torrance Combined Costs $240K $360k $130K $170k $2.8M $3.7M Combined Costs in Dominguez Channel Watershed $20M $39M $650K $1.1M $33M $61M Combined Costs of All Proposed Structural BMPs $43M $89M $2.0M $3.1M $82M $150M M = Million dollars, K = Thousand dollars
1 Life-cycle costs include construction costs and 20 years of annual O&M (in 2015 dollars) and are not discounted. 2 Alternative project locations have also been identified, but are not included in combined cost opinion

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FINANCING DISCUSSION
The availability of funds will be critical for the implementation of the EWMP. Section 7 of this EWMP provides an overview of potentially available funding sources to pay for programs proposed in the EWMP. Examples show that a multi-pronged funding strategy using multiple sources rather than rely on a single storm drain fee may be the most prudent approach. A list of potential fees and charges has been developed, which will be further considered and explored by the Beach Cities WMG in the future:
• Vehicle license and vehicle rental fees
• Solid waste management surcharge
• Water service surcharge (under AB850)
• Property assessment
• Fines (not a stable source, it is an exemption under Proposition 26) • Financial subsidy to encourage private sector participation to develop local and district projects • One time capital recovery fee
• Dedicated storm drain fee
• Taxes (e.g. fuel taxes)
• A TMDL fee / tax could be developed based on the pollutant contribution from polluters / activities
In addition, Public Private Partnerships and alternative delivery and financing methods may facilitate and streamline implementation, and could result in program cost reductions.

From the analysis of potential costs in this section as summarized in Table ES-13, it is clear that projected costs of implementing the EWMP are substantial and orders of magnitude higher than have previously been expended by the agencies under the previous MS4 Permit. Thus availability of funds will be critical for the implementation of the EWMP. Currently, the Beach Cities do not have sufficient funds or dedicated funding streams to construct and maintain the projects proposed in this EWMP.

The Beach Cities agencies are working with the Los Angeles County Division of the League of California Cities and the California Contract Cities Association to partner with other affected agencies to collectively influence State policies, pursue changes in legislation and lobby high level officials for additional stormwater funding. Working together with the other cities will increase effectiveness, communication, collaboration, and reduce redundant efforts. The LACFCD will also work with the Beach Cities in their efforts to address source controls; assess, develop, and pursue funding for structural BMPs, and promote the use of water reuse and infiltration. As regional project scopes are further refined, the LACFCD will determine on a case-by-case basis their contribution to the projects.

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In addition to working with other affected cities on a regional level, the Beach Cities WMG individually and collaboratively are committed to pursue funding sources at a local level including but not limited to:
• Grants - Collaboration and coordination between the Beach Cities will be important to increase accessible grant funding opportunities for stormwater projects, however alternative funding sources will also be needed to provide stable O&M revenues since grants typically do not provide for O&M.
• Interagency Partnerships – Interagency partnerships, like the Beach Cities WMG, can allow agencies to leverage local funding resources to make cost intensive projects possible. • Local Bond Issuance - Two types of local bonds can be utilized. General Obligation (GO) bonds are issued by local governments and repaid through a property tax surcharge. Revenue bonds are tax-exempt securitized bonds repaid through utility rate increases charged directly to customers.
• Local Stormwater Assessments - Stormwater charges are potentially the most critical local funding source to finance stormwater programs. These charges include stormwater fees and taxes.
• Direct Subsidies - Direct financial subsidies to local projects do not contribute to cash revenue generation. However, subsidies can create a financial incentive to encourage local participation without providing the full cost for project implementation. Such an approach can increase financial efficiency by leveraging financial input from communities.

These potential sources of funding are discussed in greater detail in Section 7.

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1 INTRODUCTION
Following adoption of the 2012 Los Angeles Municipal Separate Storm Sewer System (MS4) National Pollutant Discharge Elimination System (NPDES) Permit4 (Permit), the Cities of Hermosa Beach, Manhattan Beach, Redondo Beach and Torrance, together with the Los Angeles County Flood Control District (LACFCD), collectively referred to as the Beach Cities Watershed Management Group (Beach Cities WMG) agreed to collaborate on the development of an Enhanced Watershed Management Program (EWMP) for the Santa Monica Bay (SMB) and Dominguez Channel areas within their jurisdictions (referred to herein as the Beach Cities EWMP Area). This EWMP is intended to facilitate effective, watershed-specific Permit implementation strategies in accordance with Permit Part VI.C. and summarizes the SMB and Dominguez Channel-specific water quality priorities identified jointly by the Beach Cities WMG, outlines the program plan, including specific strategies, control measures and best management practices (BMPs)5, necessary to achieve water quality targets (Water Quality-Based Effluent Limitations [WQBELs] and Receiving Water Limitations [RWLs]), and describes the quantitative analyses completed to support target achievement and Permit compliance.

In compliance with Section VI.C.4.b of the Permit, the Beach Cities WMG submitted to the Los Angeles Regional Water Quality Control Board (LARWQCB) a Notice of Intent (NOI) to develop an EWMP on June 28, 2013 with a revised NOI submitted December 17, 2013. On March 27, 2014, the Beach Cities WMG received a letter from the Executive Officer of the LARWQCB approving the revised NOI submittal. In compliance with Section VI.C.4.c.iv of the Permit, the Beach Cities WMG then submitted a draft EWMP Work Plan to the LARWQCB on June 26, 2014. Comments were not received. As the next step in EWMP development, the Beach Cities WMG was required by Section VI.C.4.c.iv of the Permit to submit a draft EWMP no later than June 30, 2015. This document has been developed to serve as the Beach Cities Draft EWMP and is consistent with the Work Plan previously submitted to the LARWQCB.

1.1 PURPOSE AND REGULATORY FRAMEWORK
Watershed Management Programs (WMPs) are a voluntary opportunity afforded by Section VI.C.1 of the Permit for Permittees to collaboratively or individually develop comprehensive watershedspecific control plans and are intended to facilitate Permit compliance and water quality target achievement. Enhanced WMPs (EWMPS) are WMPs which comprehensively evaluate opportunities for collaboration on multi-benefit regional projects that retain all non-stormwater runoff and runoff from the 85th percentile, 24 hour storm event while also achieving benefits associated with issues such as flood control and water supply. Additional details on the regulatory background for NPDES

4 Order No. R4-2012-0175 NPDES Permit No. CAS004001 Waste Discharge Requirements for Municipal Separate Storm Sewer System (MS4) Discharges within the Coastal Watersheds of Los Angeles County, except those Discharges Originating from the City of Long Beach MS4. 5 For simplification, the term “BMP” will be used to collectively refer to strategies, control measures, and/or best management practices. The Permit also refers to these measures as Watershed Control Measures.

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Permit and Water Quality Standards and the Permit specifics of WMPs and EWMPs are provided below.

1.1.1 NPDES PERMIT
The 1972 Clean Water Act (CWA) established the NPDES Program to regulate the discharge of pollutants from point sources to waters of the United States. In 1990, the United States Environmental Protection Agency (USEPA) developed Phase I of the NPDES Stormwater Permitting Program, which established a framework for regulating municipal and industrial discharges of stormwater and non-stormwater that had the greatest potential to negatively impact water quality within waters of the United States. In particular, under Phase I, USEPA required NPDES Permit coverage for discharges from medium and large MS4 servicing populations greater than 100,000 persons. Operators of MS4s regulated under the Phase I NPDES Stormwater Program were required to obtain permit coverage for municipal discharges of stormwater and non-stormwater to waters of the United States.

The LARWQCB designated the MS4s owned and/or operated by the incorporated cities and Los Angeles County unincorporated areas within the Coastal Watersheds of Los Angeles County as a large MS4 due to the total population of Los Angeles County. All MS4s within the Coastal Watersheds of Los Angeles County except for the City of Long Beach MS4 are subject to the waste discharge requirements set forth in Order No. R4-2012-0175 Permit No. CAS004001. General permit requirements, which are relevant to and must be ensured by WMPs, include (i) a requirement to effectively prohibit non-stormwater discharges through the MS4, (ii) requirements to implement controls to reduce the discharge of pollutants to the maximum extent practicable, and (iii) other provisions the LARWQCB has determined appropriate for the control of such pollutants.

1.1.2 WATER QUALITY STANDARDS AND TOTAL MAXIMUM DAILY LOADS (TMDLS) The CWA also required that the RWQCB establish water quality standards for each water body in its region. Water quality standards include beneficial uses, water quality objectives and criteria that are established at levels sufficient to protect those beneficial uses, and an anti-degradation policy to prevent degrading waters. The LARWQCB adopted a Water Quality Control Plan - Los Angeles Region (hereinafter Basin Plan) on June 13, 1994 addressing this portion of the CWA which designates beneficial uses, establishes water quality objectives, and contains implementation programs and policies to achieve those objectives for all waters in the Los Angeles Region. Pursuant to California Water Code section 13263(a), the requirements of the Permit implement the Basin Plan.

The State Water Resources Control Board (State Water Board) adopted the Water Quality Control Plan for Ocean Waters in California, California Ocean Plan (hereinafter Ocean Plan) in 1972 and adopted the most recent amended Ocean Plan on September 15, 2009. The Ocean Plan also establishes water quality objectives and a program of implementation to protect beneficial uses at all MS4 discharge points within Los Angeles County coastal watersheds with the exception of Long Beach.

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CWA Section 303(d)(1) requires each state to identify the waters within its boundaries that do not meet water quality standards. Water bodies that do not meet water quality standards are considered impaired and are placed on the state’s “CWA Section 303(d) List”. For each listed water body, the state is required to establish a TMDL for each pollutant impairing the water quality standards in that water body. TMDLs establish the allowable pollutant loadings for a water body and provide the basis upon which to establish water quality-based controls (required by NPDES Permits). The 2010 CWA Integrated Report and updated 303(d) list were approved by the State Water Resources Control Board (SWRCB) on August 4, 2010 and by the USEPA on October 11,2011.

Provisions regarding TMDLs are included in NPDES Permits once they have been developed and adopted. Specific TMDLs applicable to the Beach Cities EWMP Area are discussed in more detail in Sections 2 and 3.

1.1.3 WMPS AND ENHANCED WMPS
The voluntary WMPs and EWMPs allow Permittees to collaboratively or individually develop comprehensive watershed-specific control plans which a) prioritize water quality issues, b) identify and implement focused strategies, control measures and BMPs, c) execute an integrated monitoring and assessment program, and d) allow for modification over time. In general, WMPs and EWMPs are intended to facilitate Permit compliance and water quality target achievement with the goals that: 1) discharges from covered MS4s achieve applicable WQBELs and RWLs and do not include prohibited non-stormwater discharges; and 2) control measures are implemented to reduce the discharge of pollutants to the maximum extent practicable (MEP). Per Permit Section VI.C.1.e, WMPs and EWMPs are to be developed based on the LARWQCB’s Watershed Management Areas (WMAs) or subwatersheds thereof.

Permittees within a WMA may elect to prepare an EWMP, which is defined in the Permit as a WMP that comprehensively evaluates opportunities for collaboration amongst Permittees and other partners on multi-benefit regional projects that, wherever feasible, retain, 1) all non-stormwater runoff, and 2) all stormwater runoff from the 85th percentile 24 hour storm event while also achieving benefits associated with issues such as flood control and water supply. Where regional projects cannot achieve these standards, the EWMP must demonstrate through a Reasonable Assurance Analysis (RAA), that applicable water quality targets are achieved.

The Permit specifies that an EWMP shall:

1. Be consistent with Permit provisions in Part VI.C.1.a.-f and Part VI.C.5-C.8,

2. Incorporate applicable State agency input on priorities and key implementation factors,

3. Provide for meeting water quality standards and other CWA obligations,

4. Include multi-benefit6 regional projects which retain stormwater from the 85th percentile 24 hour storm

6 Potential multiple benefits include neighborhood greening, water conservation and/or supply, groundwater recharge, public education and/or awareness, etc.

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5. Include watershed control measures which achieve compliance with all interim and final WQBELs in drainage areas where retention of the 85th percentile 24 hour storm is infeasible with reasonable assurance,

6. Maximize the effectiveness of funding,

7. Incorporate effective innovative technologies,

8. Ensure existing requirements to comply with technology based effluent limitations and core requirements are not delayed, and

9. Ensure a financial strategy is in place.

1.2 APPLICABILITY OF EWMP
The agencies of the Beach Cities WMG have been working together since 2004 to implement the previously developed Jurisdictional Groups 5 and 6 Implementation Plan for the Santa Monica Bay Beaches Bacteria (SMBBB) TMDLs, including a BMP Siting Study (Geosyntec, 2011a) and Dry Weather Source Characterization and Control Study (Geosyntec, 2011b) for two high priority subwatersheds, along with joint implementation of programmatic solutions. Since 2004, the Beach Cities have also been jointly funding receiving water monitoring consistent with the Coordinated Shoreline Monitoring Plan for the SMBBB TMDLs along the shoreline of the Beach Cities WMG EWMP Area. These ongoing efforts by the Beach Cities WMG to comply with the SMBBB TMDLs have been an effective facilitator for the development of the EWMP.

This EWMP is applicable to the Beach Cities EWMP Area, which consists of all of the incorporated MS4 areas of the cities of Redondo Beach, Manhattan Beach, Hermosa Beach and Torrance and includes the infrastructure of the LACFCD within those jurisdictions (Figure 1-1), with the exception of the Machado Lake Watershed which is being addressed separately by the City of Torrance, and is not addressed in this EWMP. A small portion of the City of Redondo Beach is located within the Machado Lake Watershed boundary but has requested to be removed from the Machado Lake Implementation Plan and other compliance requirements pertaining to the Machado Lake Watershed. Further details are described in Section 1.2.1.

The beach areas within the geographic area of the Beach Cities WMG do not have any storm drain infrastructure that collect and discharges beach runoff directly to the receiving water and are therefore considered non‐point sources and not subject to the MS4 Permit or EWMP requirements.

Similarly, the Hermosa Beach and Manhattan Beach piers are not part of the MS4; they are non‐ point sources excluded from the MS4 Permit scope and therefore the EWMP. The Redondo Beach Pier including the King Harbor Marina are included in the geographic scope of the Beach Cities WMG EWMP as these areas are equipped with MS4 infrastructure. The Wylie Sump, Bishop Montgomery Basin, and Ocean Basin are all retention basins with no outlet. Therefore, their drainage areas have been excluded from the EWMP, with no analyses required. The Del Amo Retention Basin also has not outlet, and is sized to capture runoff from at least the 85th percentile, 24 hour storm event.

Because the Del Amo Retention Basin is within the Machado Lake Watershed, this drainage area is excluded from the EWMP.

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Figure 1-1. Beach Cities EWMP Area

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1.2.1 CITY OF REDONDO BEACH CONTRIBUTION AND COMPLIANCE STRATEGY IN THE

MACHADO LAKE WATERSHED
Machado Lake is a 40 acre lake located in the Ken Malloy Harbor Regional Park and is managed by the City of Los Angeles, Department of Recreation and Parks. The Machado Lake watershed includes portions of Lomita, Torrance, Carson, City of Los Angeles, County of Los Angeles, Palos Verdes Estates, Rancho Palos Verdes, Rolling Hills, Rolling Hills Estates and California Department of Transportation.

Machado Lake is listed on the 1998, 2002, and 2006, and 2010 Clean Water Act Section 303(d) lists of impaired water bodies due to eutrophic conditions, algae and odors (Nutrients); chlordane, dichlorodiphenyltrichloroethane (DDT), dieldrin, Chem A, and PCBs in tissue; and impaired sediment due to chlordane, DDT, and PCBs (Toxics). The listed impairments are caused by the overloading of nutrients, such as nitrogen and phosphorus, resulting in excessive algal growth which leads to increased turbidity, decreased levels of oxygen, and odor problems. The Los Angeles Regional Water Quality Control Board (RWQCB) established TMDLs for Machado Lake for algae, ammonia and odors (Nutrients) on May 1, 2008, and for Pesticides and PCBs (Toxics) on September 2, 2010. In addition, on June 7, 2007, the RWQCB adopted an amendment to the Water Quality Control Plan for the Los Angeles Region (Basin Plan) incorporating a TMDL for Trash in Machado Lake (March 6, 2008 was the effective date of the Machado Lake Trash TMDL).

The Machado Lake TMDL describes the watershed as:
“Machado Lake is a receiving body of urban and storm water runoff from the storm drain system covering an approximately 20-square mile watershed. The Wilmington Drain collects runoff from the surrounding cities of Lomita, Torrance, Carson, and Los Angeles, and then discharges over 50 percent of the watershed into Machado Lake at the northeast corner. The rest of the waters enter the lake through other storm drains including the Project No. 77 channel, the Harbor City Relief Drain located at the west end of the lake, the City of Los Angeles drains for runoff from streets, and the Harbor Park Municipal Golf Course. The Wilmington Drain Project 77 and the Harbor City Relief Drain collect storm water from the communities of Harbor City, Lomita, Carson, Torrance, and Wilmington, and from the Walteria Lake drainage area. In addition, two project 643 outlets discharge to the wetlands area. During the dry season, Machado Lake is replenished via a City of Los Angeles Department of Water And Power potable water pipeline and dry weather runoff.” The City of Redondo Beach is situated in the western portion of the Machado Lake subwatershed and makes up 0.018% (approximately 0.94 acres) of the total watershed area. This has been reduced from previously reported percentages based on a staff field visit the week of January 4, 2016 during a heavy rain event when stormwater runoff from a small area was observed to drain to the Santa Monica Bay, not Machado Lake, as previously assumed. The City of Redondo Beach has no direct discharges into Machado Lake and has 0 (zero) point source area miles, which results in a calculated waste load allocation of zero for the City’s drainage area. The City’s contributory drainage area consists of no catch basins or storm drains.

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Two corrected watershed maps identifying the drainage area are attached as Appendices C and D in this EWMP. The drainage from the City’s area to Machado Lake has been determined to be “de minimus” and poses an insignificant threat to Machado Lake water quality and pollutant loading.

The City of Redondo Beach will manage and included this described area as part of the City’s Santa Monica Bay Beaches Bacteria (SMBBB) TMDL and overall MS4 NPDES program, including the implementation of all minimum control measures and oversight.

The City of Redondo Beach sent a letter to the State Water Resources Control Board dated October 31, 2007 (Appendix E) requesting to be exempted from the Machado Lake Trash TMDL and sent another letter to the RWQCB on December 18, 2008 (Appendix F) requesting the City be removed as a responsible agency under the Machado Lake TMDL requirements. The Watershed agencies agreed to this; therefore, they did not included the City of Redondo Beach in the Machado Lake Trash TMDL Monitoring and Reporting Plan.

Based on these items, the City of Redondo Beach has requested to be deemed “in-compliance” with their Machado Lake Watershed drainage area and be removed from the Machado Lake Watershed Implementation Plan for the following reasons:
• The City of Redondo Beach’s drainage area is only 0.018% (approximately 0.94 acres) of the total Machado Lake Watershed area. This area has been determined to be “de minimus” and post an insignificant threat to Machado Lake Watershed water quality and pollutant loading.

The portion of the City’s contributory drainage area consists of no catch basins or storm drains. • The City of Redondo Beach proposes that it would be more reasonable for the City to focus its resources to implement the SMBBB TMDL and other relevant TMDLs. The majority of the City land area discharges into the Santa Monica Bay, which would make it more feasible and effective to use resources on projects and programs that will have the most impact on water quality improvements. The insignificant area draining into Machado Lake would be subject to the same control measures of the implementation plan developed for the SMBBB TMDL and all other MS4 NPDES measures. As a result, this area would benefit from the appropriate BMPs designed for the entire City.

1.3 EWMP DEVELOPMENT PROCESS
Section VI.C.1.f.v of the Permit requires a stakeholder process for collaboration on EWMP development. The development process must:
• Provide appropriate opportunity for stakeholder input; • Include participation in the Permit-wide Technical Advisory Committee (TAC); and • Incorporate applicable State agency input on priority setting and other key implementation issues.

The Beach Cities WMG has conducted public outreach to engage the public, LARWQCB staff, and other interested parties to support EWMP development. Input has been incorporated as appropriate. These efforts are described in more detail below.

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Public Workshops. Public workshops were held on May 21, 2014 at the Joslyn Center in Manhattan Beach and on May 27, 2015 at the Redondo Beach Public Library. An informational presentation was provided followed by a question and answer period to encourage stakeholder input. Concerns were noted and considered during EWMP development by the Beach Cities WMG.

Technical Advisory Committee (TAC). The Beach Cities WMG has, and will continue to, actively participate in the Los Angeles region TAC and applicable subcommittees throughout the EWMP process.

LARWQCB Presentations. The Beach Cities WMG presented the proposed RAA approach to LARWQCB staff on April 9 and June 6, 2014. LARWQCB staff provided feedback during these meetings and in general they were supportive of the proposed approach. One additional meeting was held on July 31, 2014 to discuss Torrance-specific matters.

The EWMP also addressed other State agency priorities, including the following:

California Water Action Plan (2014). The California Water Action Plan proposes several statewide actions that are well aligned with the expected benefits of the proposed projects in this EWMP, including:
• Expand Water Storage Capacity and Improve Groundwater Management (infiltration BMPs): This action aims to address the need to expand the state’s storage capacity, whether in surface or groundwater to provide widespread public and environmental benefits. The California Water Action Plan states that “state agencies will work with tribes and federal, regional and local agencies on other actions related to promoting groundwater recharge and increasing storage, including improving interagency coordination, aligning land use planning with groundwater recharge...” The regional and distributed BMP projects proposed in the Beach Cities EWMP may contribute to groundwater recharge and expanding storage capacity throughout the Beach Cities WMG.
• Increase Operational and Regulatory Efficiency: Monitoring data collected under the CIMP to measure progress toward achieving RWLs and WQBELs and to determine if modifications to the Beach Cities EWMP are necessary may provide the benefit of increased operational and regulatory efficiency. Improving data availability may also improve coordination of operations of all major water supply, flood control, hatchery facilities, and habitat restoration projects.
2014 Greater Los Angeles County Integrated Regional Water Management Plan (GLAC IRWM Plan). The goal of the GLACR IRWM Plan is to achieve sustainable management of water resources in the Greater Los Angeles County. The plan lists several regional objectives to achieve this goal. The Beach Cities EWMP contributes to some of the objectives outlined in the plan, including the following:

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• Water Quality: This objective aims to comply with water quality regulations by improving the quality of urban runoff, stormwater, and wastewater. The Beach Cities EWMP contributes to this objective by proposing new distributed and regional stormwater capture opportunities in areas prioritized by statewide and regional regulations and water quality conditions.
• Open Space and Recreation: This objective aims to protect, restore, and enhance natural process and habitats. Several of the regional EWMP projects (i.e. Park #3 BMP and the Powerline Easement in Analysis Region SMB-6-01) provide opportunity for expanded habitat and increased green space.

STORMS Storm Water Strategy (California Water Boards, 2015). The Storm Water Strategy assists in achieving the actions identified in the California Water Action Plan, including the aforementioned action of expanding water storage capacity and improving groundwater management. The Storm Water Strategy supports efforts to improve interagency coordination and identify needs for groundwater recharge opportunity. The Storm Water Strategy also lists six overarching objectives. The Beach Cities EWMP contributes to some of these objectives, including the following:
• Increase Stakeholder Collaboration on a Watershed Scale: the Beach Cities WMG agreed to collaborate on the development of this EWMP for the Santa Monica Bay and Dominguez Channel Watershed areas within their jurisdictions to facilitate effective, watershed-specific Permit implementation strategies in accordance with Permit Part VI.C.
• Establish Financially Sustainable Storm Water Programs: This EWMP provides an overview of potentially available funding sources for programs proposed in the EWMP. The funding sources identified for consideration are grants, interagency partnerships, bonds, State Revolving Funds, local funding opportunities, and public private partnerships.
• Increase Source Control and Pollution Prevention: This EWMP identifies the cumulative benefits from non-modeled programmatic source control BMPs that target the pollutants addressed in this EWMP.

Final Storm Water Resource Plan Guidelines (Guidelines) (December 2015). The Guidelines establish guidance for public agencies to develop Storm Water Resource Plans (Plans) consistent with Water Code sections 10561 through 10565. The Water Code states that a Plan is required as a condition to receive funding for stormwater and dry weather runoff capture projects from any bond approved by voters after January 2014, which also applies to Proposition 1 funding. The Guidelines provide guidance such as clarification on the applicability of the Guidelines, appropriate geographic scale of watersheds for stormwater resource planning, guidance on agencies and organizations to be consulted during Plan development, methods for identifying and prioritizing stormwater and runoff capture projects, project scheduling and implementation strategies, and so forth.

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A Self-Certified Checklist provided in the Guidelines includes a complete list of the elements of a Stormwater Resource Plan that are considered mandatory per the California Water Code. Fulfilling the mandatory requirements would make the Beach Cities WMG eligible for Proposition 1 Stormwater Grant funding which would be applied toward the proposed Beach Cities EWMP projects. The mandatory required elements highlighted in the Checklist and Self-Certification are either entirely fulfilled by the Beach Cities EWMP (including appended documents) or will be fulfilled on a project-specific basis. For example, maximizing flood control will be part of detailed design at the project level.

1.4 REPORT ORGANIZATION
This Beach Cities EWMP addresses the required EWMP elements from Section VI.C. of the Permit for both the SMB and Dominguez Channel Watersheds. Because the SMB and Dominguez Channel Watersheds have their own unique water quality conditions, their technical evaluations were performed independently and are documented in separate sections in this EWMP. This includes the water quality prioritization, RAA, and BMP identification. Section 2 summarizes the technical aspects of the EWMP for Santa Monica Bay watershed while Section 3 covers the same technical elements for Dominguez Channel Watershed. Section 4 presents individual EMWP implementation schedules for both watersheds. In Section 5, the adaptive management process proposed by the Beach Cities WMG is described, and in Section 6, the cost opinions associated with EWMP implementation are summarized. Section 7 describes potential funding sources and financial strategies. Sections 8 and 9 include the legal authority and references, respectively.

1.5 TERMS OF REFERENCE
This work was conducted by Geosyntec Consultants for the Beach Cities WMG with the purpose of developing a comprehensive control plan to facilitate Permit compliance and achievement of water quality standards and serves as the deliverable for Task 4.5 of the Beach Cities WMP contract. This work was managed by Ken Susilo, P.E., D.WRE., CPSWQ, with support from Megan Otto, P.E., Chris Wessel, P.E., Stacy Luell, P.E, Stacey Schal, Curtis Fang, and Scott Mansell, Ph.D. Peer review was provided by Megan Otto, P.E., Chris Wessel, P.E., and Lucas Nguyen. Senior review was provided by Brandon Steets, P.E. and Ken Susilo, P.E., in accordance with Geosyntec's quality assurance policies.

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2 SANTA MONICA BAY WATERSHED

2.1 BACKGROUND

2.1.1 GEOGRAPHICAL CONTEXT
The western portion of the Beach Cities EWMP Area consists of approximately 7,840 acres of land that drains to SMB. This accounts for 52% of the total Beach Cities WMG area, and includes portions of the cities of Manhattan Beach, Redondo Beach, and Torrance, and the entirety of the City of Hermosa Beach (Figure 2-1). This portion of the study area is hereinafter referred to as the SMB Watershed. The majority of the SMB Watershed consists of residential land uses (Figure 2-2).

The LACFCD is not responsible for land within the Beach Cities EWMP Area, but does own and maintain infrastructure within all three watersheds. Background information on the LACFCD is provided in Appendix G. Table 2-1 provides a breakdown of the Beach Cities EWMP Area by agency and watershed. This section of the EWMP focuses on the SMB Watershed only.

Table 2-1. Beach Cities WMG EWMP Area Distribution by Participating Agency Participating Agency
Area (acres)
Santa Monica Bay
Watershed
Dominguez Channel
Watershed
Total EWMP Area
(% of total)
City of Redondo Beach 2,614 1,217 3,831 (25%)
City of Manhattan Beach 2,078 350 2,428 (16%)
City of Hermosa Beach 832 - 832 (5%)
City of Torrance 2,314 5,812 8,126 (53%)
Total 7,837 7,379 15,217 (100%)

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Figure 2-1. Beach Cities WMG MS4 Infrastructure within the Santa Monica Bay Watershed

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Figure 2-2. Beach Cities WMG Land Uses within the Santa Monica Bay Watershed

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2.2 IDENTIFICATION OF WATER QUALITY PRIORITIES
As part of the EWMP, the Permit requires the Beach Cities WMG to identify water quality priorities within their WMA. To accomplish this per Permit Section VI.C.5.a, the Beach Cities WMG conducted the following for the Santa Monica Bay watershed portion of the Beach Cities EWMP Area:

1. Characterize the water quality of stormwater and non-stormwater discharges from the MS4 as well as receiving water bodies;

2. Prioritize water body-pollutant combinations (WBPCs); and

3. Assess sources for high priority water body.

A summary of results is provided below.

2.2.1 WATER QUALITY CHARACTERIZATION
Beneficial Uses
The Basin Plan (LARWQCB, 1995, updated 2011) identifies receiving waters within the Los Angeles region and sets regulatory objectives for these receiving waters. Within the SMB Watershed, identified receiving water bodies include SMB itself as well as coastal beaches within the Beach Cities WMG Area. Regulations set forth in the California Ocean Plan (SWRCB, 2012) are therefore also applicable to the SMB Watershed.

Both the Basin Plan and Ocean Plan regulate waste discharges to protect the quality of surface waters for use and enjoyment by the general public. Regulations set forth in the Basin Plan are based on assigned beneficial uses for each receiving water body. Beneficial use designations for receiving waters within the Beach Cities WMG Area include:
• Municipal and Domestic Supply (MUN): Uses of water for community, military, or individual water supply systems including, but not limited to, drinking water supply. • Industrial Service Supply (IND): Uses of water for industrial activities that do not depend primarily on water quality including, but not limited to, mining, cooling water supply, hydraulic conveyance, gravel washing, fire protection, or oil well re-pressurization. • Navigation (NAV): Uses of water for shipping, travel, or other transportation by private, military, or commercial vessels.
• Water Contact Recreation (REC-1): Uses of water for recreational activities involving body contact with water, where ingestion of water is reasonably possible. These include, but are not limited to, swimming, wading, water-skiing, skin and scuba diving, surfing, what water activities, fishing, or use of natural hot springs.
• Non-Contact Water Recreation (REC-2): Uses of water for recreational activities involving proximity to water, but not normally involving body contact with water, where ingestion of water is reasonably possible. These uses include, but are not limited to, picnicking, sunbathing, hiking, beachcombing, camping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above activities.

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• High Flow Suspension (HFS): Applies to water contact recreational activities associated with the swimmable goal regulated under the REC-1 use, non-contact water recreation involving incidental water contact regulated under the REC-2 use, and the associated bacteriological objectives set to protect those activities.
• Commercial and Sport Fishing (COMM): Uses of water for commercial or recreational collection of fish, shellfish, or other organisms including, but not limited to, uses involving organisms intended for human consumption or bait purposes. • Warm Freshwater Habitat (WARM): Uses of water that support warm water ecosystems including, but not limited to, preservation or enhancement of aquatic habitats, vegetation, fish, or wildlife, including invertebrates.
• Marine Habitat (MAR): Uses of water that support marine ecosystems including, but not limited to, preservation or enhancement of marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g., marine mammals, shorebirds). • Wildlife Habitat (WILD): Uses of water that support terrestrial ecosystems including, but not limited to, preservation and enhancement of terrestrial habitats, vegetation, wildlife (e.g., mammals, birds, reptiles, amphibians, invertebrates), or wildlife water and food sources. • Rare, Threatened, or Endangered Species (RARE): Uses of water that support habitats necessary, at least in part, for the survival and successful maintenance of plant or animal species established under state or federal law as rare, threatened, or endangered. • Migration of Aquatic Organisms (MIGR): Uses of water that support habitats necessary for migration, acclimatization between fresh and salt water, or other temporary activities by aquatic organisms, such as anadromous fish.
• Spawning, Reproduction, and/or Early Development (SPWN): Uses of water that support high quality aquatic habitats suitable for reproduction and early development of fish. • Shellfish Harvesting (SHELL): Uses of water that support habitats suitable for the collection of filter-feeding shellfish (e.g., clams, oysters, and mussels) for human consumption, commercial, or sports purposes.
• Wetland Habitat (WET): Uses of water that support wetland ecosystems, including, but not limited to, preservation or enhancement of wetland habitats, vegetation, fish, shellfish, or wildlife, and other unique wetland functions which enhance water quality, such as providing flood and erosion control, stream bank stabilization, and filtration and purification of naturally occurring contaminants.

According to the Ocean Plan (SWRCB, 2012), “The beneficial uses of the ocean waters of the State that shall be protected include industrial water supply (IND); water contact recreation (REC-1) and non-contact recreation (REC-2), including aesthetic enjoyment; navigation (NAV); commercial and sport fishing (COMM); mariculture; preservation and enhancement of designated Areas of Special Biological Significance (ASBS); rare and endangered species (RARE); marine habitat (MAR); fish migration (MIGR); fish spawning (SPWN) and shellfish* harvesting (SHELL).” Additional beneficial uses are defined as follows:

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• Mariculture: The culture of plants and animals in marine waters independent of any pollution source.
• ASBS: Those areas designated by the State Water Board as ocean areas requiring protection of species or biological communities to the extent that maintenance of natural water quality is assured. ASBS are also referred to as State Water Quality Protection Areas – Areas of Special Biological Significance (SWQPA-ASBS).

Table 2-2 summarizes the existing beneficial uses for the Santa Monica Bay water bodies in the Beach Cities WMG Area, as designated in the Basin Plan.

Table 2-2. Beach Cities EWMP Area - Santa Monica Bay Watershed Water Bodies and Beneficial Uses
Water Body
MUNINDNAVREC1REC2HFSCOMMWARMMARWILDRAREMIGRSPWNSHELLWET2 Santa Monica Bay
Nearshore +
Offshore1

E E E E E E E E E E E
Manhattan Beach E E E E E E P E
Hermosa Beach E E E E E E E3 E
King Harbor E E E E E E E E
Redondo Beach E E E E E E E E E E3 E
Torrance Beach E E E E E E E E3 E
E = Existing beneficial use
1 The Preservation of Biological Habitats (BIOL) beneficial use is not included since no Areas of Special Biological Significance are present within the Beach Cities WMG Area. 2 Water bodies designated as WET may have wetlands habitat associated with only a portion of the water body. Any regulatory action would require a detailed analysis of the area. 3 Most frequently used grunion spawning beaches. Other beaches may be used as well.

SMB Watershed Data Analysis
An evaluation of existing water quality conditions, including characterization of stormwater discharges from the MS4 as well as receiving water quality was carried out as part of this EWMP to support identification and prioritization/sequencing of management actions, to the extent possible based on available data. To evaluate water-quality conditions within the SMB Watershed, a review of previous studies was conducted to characterize receiving water bodies within the Beach Cities WMG Area. Monitoring data analyzed were limited to bacteria data collected as part of the SMB Beaches Bacteria TMDL CSMP and limited PCB and DDT data collected as part of the 2008 Bight Regional Monitoring Program. A summary of this analysis is provided below. Additional details can be found in the Beach Cities EWMP Work Plan.

2.2.2 WATER BODY-POLLUTANT CLASSIFICATION
Receiving waters for stormwater runoff from the Santa Monica Bay Watershed portion of the Beach Cities EWMP Area were screened for water quality priorities by reviewing TMDLs, the State’s

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303(d) list, and additional water quality data. Each identified water quality priority for a given receiving water body was categorized as a WBPC. WBPCs were classified into one of three categories, in accordance with Section VI.C.5(a).ii of the Permit. No 303(d) listings exist beyond the TMDL WBPCs, and no other recent monitoring data are available beyond the SMBBB TMDL Coordinated Shoreline Monitoring Plan (CSMP) data; therefore, no Category 2 or 3 WBPCs have been identified for the Beach Cities portion of SMB at this time.

Category 1 – Highest Priority
WBPCs under Category 1 (highest priority) are defined in the Permit as “water body-pollutant combinations for which WQBELs and/or RWLs are established in Part VI.E and Attachments L through R of [the Permit].” These WBPCs include:
• SMB beaches for bacteria (wet and dry weather): These are considered Category 1 due to the SMBBB TMDL.
• SMB offshore/nearshore for dichloro-diphenyl-trichloroethanes (DDTs) and polychlorinated biphenyls (PCBs)7: These are considered Category 1 due to the USEPA TMDL for DDT and PCBs for SMB Offshore/Nearshore. However, the TMDL relies on a limited dataset to establish stormwater load allocations, relying on a single study (Curren et al., 2011) from a single creek (Ballona Creek, which is outside the Beach Cities watershed area) to establish MS4 WLAs throughout the entire SMB Watershed. It does not present sufficient data to assign MS4 contributions to the DDT and PCB concentrations observed in SMB; therefore, standard RAA modeling for these pollutants cannot reasonably be conducted at this time.

Despite the lack of data for RAA modeling purposes, the load-based WQBELs for DDT and PCBs established by the TMDL were set to be the existing stormwater loads (i.e., based on data used in the TMDL, no MS4 load reduction is expected to be required to achieve TMDL compliance)8.

Therefore, it is assumed that no reductions in DDT and PCB loading from the Beach Cities WMG MS4s are required to meet the TMDL and reasonable assurance of compliance is assumed to be demonstrated without modeling. Monitoring of these pollutants will occur under the Beach Cities CIMP.

7 SMB Offshore/Nearshore is 303(d)-listed for fish consumption advisory due to DDT and PCBs. Therefore, the fish consumption advisory will be assumed to be addressed by the DDT and PCB categorization. SMB Offshore/Nearshore is also 303(d) listed for toxicity. USEPA's data evaluation showed only 3 out of 116 samples exhibited toxicity (USEPA, 2012). USEPA made a finding in the TMDL that, following the California listing policy, Santa Monica Bay is meeting the toxicity objective and there is sufficient evidence to de-list sediment toxicity. EPA therefore concluded in the TMDL that there is no significant toxicity in Santa Monica Bay and recommended that Santa Monica Bay not be identified as impaired by toxicity in the California's next 303(d) list.
8 The TMDL states, “Because existing stormwater loads from the watersheds are lower than the calculated total allowable loads to achieve sediment targets, the waste load allocations for stormwater in this TMDL are based on existing load estimates of 28 g/yr for DDT and 145 g/yr for PCBs.” These WLAs are further divided among Los Angeles County MS4, CalTrans, the Construction General Permit, and the Industrial General Permit. The assigned WLAs for the entire LA County MS4 within the Santa Monica Bay Watershed is 27.08 g/yr for DDT and 140.25 g/yr for PCBs, which are equivalent to the TMDL-estimated existing MS4 stormwater loads.

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• SMB offshore/nearshore for debris: This is considered Category 1 due to the TMDL for Debris for SMB Offshore/Nearshore. Section VI.E.5.b(i) of the Permit states, “Pursuant to California Water Code section 13360(a), Permittees may comply with the trash [debris] effluent limitations using any lawful means. Such compliance options are broadly classified as full capture, partial capture, institutional controls, or minimum frequency of assessment and collection… and any combination of these may be employed to achieve compliance.” While trash was not modeled as part of the RAA, the RAA qualitatively described how the Beach Cities WMG Agencies will comply with the SMB Debris TMDL WQBELs by stating the following: “Compliance with the Debris TMDL will be met through a phased retrofit of all catch basins throughout the SMB EWMP area to meet each interim compliance deadline (20% load reduction per year between 2016 and 2019) as well as the final compliance deadline (100% load reduction) in 2020. Consistent with the Trash Monitoring and Reporting Plans (TMRP) from each of the Beach Cities agencies (Beach Cities WMP, 2014), “vertical insert[s] with 5-mm openings and flow activated opening screen covers are the best suited for implementation within the City to achieve compliance with Trash TMDLs.” To date, data for trash discharges from the MS4 are unavailable for the SMB Watershed.

The SMB Debris TMDL can be satisfied through the submittal of the TMRP and the Plastic Pellet Monitoring and Reporting Program (PMRP) or via the CIMP. Trash Monitoring and Reporting Plans (TMRPs) were submitted to the Regional Board by each Beach Cities WMG Agency before the TMDL-specified deadline of September 20, 2012. Additionally, each Beach Cities WMG Agency submitted a request to the Regional Board by September 20, 2013 to be exempt from the TMDL requirement to conduct monitoring for plastic pellets based on absence of industrial activities related to the manufacturing, handling, or transportation of plastic pellets within their jurisdictions in the SMB watershed. A review letter on the draft CIMP, dated May 22, 2015, approved the TMRP and PMRP exemption requests from the City of Hermosa Beach, the PMRP exemption request from the City of Torrance, the PMRP exemption request from the City of Manhattan Beach, and the three year extension of the final TMRP compliance date for the City of Manhattan Beach (LARWQCB, 2015). The Board approved the TMRP for the City of Redondo Beach on May 22, 2015. The City of Redondo Beach request for exemption from the PMRP was approved by the Board on November 12, 2015 [LARWQCB, 2015c]. Monitoring for trash in the City of Redondo Beach, City of Manhattan Beach, City of Hermosa Beach, and City of Torrance will begin in the SMB Watershed in accordance with each Agency’s respective TMRP.

Exemption of the Beach City WMG Agencies from the PMRP means that monitoring for plastic pellets within the SMB Watershed will not be conducted by the Beach Cities. “Highest Priority” WBPCs have been assigned based strictly on the Permit definition. Not all of these pollutants (e.g., DDT and PCBs) have been definitively linked to MS4 sources. As a result, this categorization and prioritization will be reevaluated based on results from the future water quality monitoring efforts conducted under the Coordinated Integrated Monitoring Program (CIMP).

Category 2 – High Priority
WBPCs under Category 2 (high priority) are defined in the Permit as, “Pollutants for which data indicate water quality impairment in the receiving water according to the State’s Water Quality

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Control Policy for Developing California’s Clean Water Act Section 303(d) List (State Listing Policy) (SWRCB, 2004) and for which MS4 discharges may be causing or contributing to the impairment.” There are no Category 2 WBPCs in the SMB Watershed portion of the Beach Cities EWMP area.

Category 3 – Medium Priority
WBPCs under Category 3 (medium priority) are defined in the Permit as, ”Pollutants for which there are insufficient data to indicate water quality impairment in the receiving water according to the State’s Listing Policy, but which exceed applicable RWLs contained in this Order and for which MS4 discharges may be causing or contributing to the exceedance.” There are no Category 3 WBPCs in the SMB Watershed portion of the Beach Cities EWMP area.

The Beach Cities WMG agencies understand that data collected as part of their approved CIMP may result in future Category 3 designations in instances when RWLs are exceeded and MS4 discharges are identified as contributing to such exceedances. Under these conditions, the Beach Cities WMG agencies will adhere to Section VI.C.2.a.iii of the Permit and the EWMP will be updated.

Figure 2-3 provides a brief conceptual overview of the process used to identify and categorize the WBPCs within the Beach Cities EWMP Area.

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Figure 2-3. Process for Categorizing Water Body-Pollutant Combinations Table 2-3 presents the prioritized WBPCs within the SMB Watershed portion of the Beach Cities EWMP Area. WBPCs categorized below are subject to change based on future data collected as part of the CIMP or other monitoring program. Grouped RWLs for the SMB Beaches Bacteria TMDL are also expressed in the Permit in terms of allowable exceedance days (AEDs), which vary by season and by Coordinated Shoreline Monitoring Plan (CSMP) monitoring station. These AEDs, as revised per the Reconsideration of the SMB Beaches Bacteria TMDL (LARWQCB, 2012b), are summarized in Table 2-4. The final grouped RWLs are effective for dry weather and will be effective July 15, 2021 for wet weather. The CSMP monitoring stations are shown in Figure 2-5.

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Table 2-3. Water Body-Pollutant Combination Prioritization and Pollutant Interim and Final Compliance Targets for Santa Monica Bay Watershed Portion of the Beach Cities EWMP Area Category Water
Body Pollutant Reason for Categorization WQBEL/RWL/Objective Basis Interim WQBEL/
RWL
Final WQBEL/
RWL/Objective
1:

Highest
Priority
Santa
Monica
Bay
Beaches
Dry
Weather
Bacteria
SMB Beaches Dry Weather
Bacteria TMDL
Daily and Weekly
Sampling Schedule N/A
Summer-Dry Single Sample
Allowable Exceedance Days
(AED)1 met
Winter-Dry period Single
Sample AED1 met
Wet
Weather
Bacteria
SMB Beaches Wet Weather
Bacteria TMDL
Daily and Weekly
Sampling
Schedule/
50% cumulative
percentage reduction from
total required exceedance
day reduction2
Single Sample and
Geometric Mean AED1 and
GM target met
Santa
Monica
Bay
Trash/
Debris SMB Debris TMDL Annual monitoring
Incremental reduction
from baseline waste load
allocation3 (6815.6
gals/year)
100% reduction from
baseline waste load
allocation3 (6815.6
gals/year)
DDTs SMB PCBs and DDT TMDL 3-Year Average N/A 27.08 g/year4 PCBs SMB PCBs and DDT TMDL 3-Year Average N/A 140.25 g/year4 2: High
Priority N/A None
No other 303(d) listings exist
for the Beach Cities portion
of SMB
3:

Medium
Priority
N/A None
Outfall and receiving water
monitoring data are not
available for the Beach Cities
portion of SMB
1Per the Basin Plan Objective REC1 Water Bodies Limit for Bacteria. Please refer to Table 2-4 for allowable exceedance day limits of each subwatershed. 2 Total required exceedance day reduction is defined as the difference between existing exceedance day and the allowable exceedance day for each subwatershed
3 Baseline WLA is the sum of baseline WLA from Manhattan Beach, Redondo Beach and Hermosa Beach 4This limit is applicable to all of Santa Monica Bay.

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Table 2-4. Bacteria RLWs for Beach Cities WMG Shoreline Monitoring Stations Station Station Name
Summer Dry Weather
(Apr 1 – Oct 31)
Winter Dry Weather
(Nov 1 – Mar 31)a
Wet Weather
(Year-Round)
Daily
Sampleb
Weekly
Sample
Daily
Sampleb
Weekly
Sample
Daily
Sampleb
Weekly
Sample
SMB 5-01c Manhattan State Beach at 40th St
(El Porto Beach) 0 0 1 1 4 1
SMB 5-02 Terminus of 28th Street Drain in
Manhattan Beach 0 0 9 2 17 3
SMB 5-03 Manhattan Beach Pier 0 0 3 1 6 1
SMB 5-04c Near 26th Street on Hermosa
Beach 0 0 3 1 12 2
SMB 5-05c Hermosa Beach Pier 0 0 2 1 8 2
SMB 6-01 Herondo Storm Drain 0 0 9 2 17 3
SMB 6-02c Redondo Municipal Pier – 100
Yards South 0 0 3 1 14 2
SMB 6-03 4’x4’ Outlet at Projection of
Sapphire Street 0 0 5 1 17 3
SMB 6-04c 120’ North of Topaz groin 0 0 9 2 17 3
SMB 6-05 Storm Drain at Projection of
Avenue I 0 0 4 1 11 2
SMB 6-06c Malaga Cove, Palos Verdes
Estates 0 0 1 1 3 1
a The number of allowable exceedance days established in the revised TMDL have increased from the values outlined in the original TMDL. b SMB 5-02 and SMB 6-01 are the only monitoring sites that have been sampled daily (5 days/week), although SMB 6-01 switched to weekly sampling in 2013. All other monitoring sites were sampled weekly (on average). c SMB 5-01, 5-04, 5-05, 6-02, 6-04, and 6-06 are all open beach monitoring locations which are not associated with major storm drain outfalls.

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Sections VI.C.2 and VI.C.3 of the Permit describes how compliance with RWLs/WQBELs is attained for the prioritized WBPCs identified. Appendix H sets forth the EWMP framework for evaluating and addressing receiving water exceedances and a brief summary is included below.

Different actions are required to demonstrate compliance for different types of WBPCs. Specifically; the following classifications are addressed by the Permit:
• WBPCs addressed by a TMDL.
• 303(d)-listed WBPCs: Pollutants in the same class as those identified in a TMDL and for which the water body is 303(d)-listed (Section VI.C.2.a.i), and pollutants not in the same class as those identified in a TMDL, but for which the water body is 303(d)-listed (Section VI.C.2.a.ii). • Non 303(d)-listed WBPCs: Pollutants for which there are exceedances of RWLs, but for which the water body is not 303(d)-listed (Section VI.C.2.a.iii).

For Category 1 WBPCs, adherence to all implementation actions and compliance dates identified in the approved EWMP will constitute compliance with applicable TMDL-based interim water quality based effluent limits and interim receiving water limits. For any Category 2 and 3 WBPCs that are identified in the future through the adaptive management process, adherence to all implementation actions, milestones, and compliance schedules identified in the updated EWMP will constitute compliance with applicable receiving water limits. This approach is outlined in Appendix H.

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2.2.3 SOURCE ASSESSMENT
The following data sources were reviewed as part of the source assessment for the WBPCs listed previously:
• Findings from the Permittees’ Illicit Connections and Illicit Discharge Elimination Programs (IC/ID);
• Findings from the Permittees’ Industrial/Commercial Facilities Programs; • Findings from the Permittees’ Development Construction Programs; • Findings from the Permittees’ Public Agency Activities Programs; • TMDL source investigations;
• Watershed model results;
• Findings from the Permittees’ monitoring programs, including but not limited to TMDL compliance monitoring and receiving water monitoring; and • Any other pertinent data, information, or studies related to pollutant sources and conditions that contribute to the highest water quality priorities.

The following source assessment is broken down by pollutants applicable to the SMB Watershed.

Indicator Bacteria
The SMBBB TMDLs for dry and wet weather were the first bacteria TMDLs adopted by the LARWQCB. The SMBBB TMDLs were recently opened for reconsideration, although the source assessment was not part of this update. As a result, the general findings from the original source assessment remain unchanged. These findings are summarized in the 2012 Basin Plan Amendment for the reopened SMBBB TMDL (Attachment A to Resolution No. R12-007):
“With the exception of isolated sewage spills, dry weather urban runoff and stormwater runoff conveyed by storm drains and creeks is the primary source of elevated bacterial indicator densities to SMB beaches. Limited natural runoff and groundwater may also potentially contribute to elevated bacterial indicator densities during winter dry weather” (LARWQCB, 2012b).

The SMBBB TMDL source assessment (LARWQCB, 2002) maintained that dry weather urban runoff and stormwater runoff were the primary sources of elevated bacteria concentrations at SMB beaches at the time of the TMDL. Although definitive information regarding the specific sources of bacteria within the watershed was not presented, speculation provided in the dry weather staff report provided some insight into possible sources at the time:
“Urban runoff from the storm drain system may have elevated levels of bacterial indicators due to sanitary sewer leaks and spills, illicit connections of sanitary lines to the storm drain system, runoff from homeless encampments, illegal discharges from recreational vehicle holding tanks, and malfunctioning septic tanks among other things. Swimmers can also be a direct source of bacteria to recreational waters. The bacteria indicators used to assess water quality are not specific to human sewage; therefore, fecal matter from animals and birds can also be a source

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of elevated levels of bacteria, and vegetation and food waste can be a source of elevated levels of total coliform bacteria, specifically” (LARWQCB, 2002).

Information on non-MS4 sources of surf zone bacteria along specific SMB beaches was provided by the City of Malibu in its comment letter on the SMBBB TMDL reconsideration, based on a comprehensive review of local and Southern California source identification studies (City of Malibu, 2012):
“A number of recent Santa Monica Bay studies have further identified and confirmed natural (non-anthropogenic) sources of fecal indicator bacteria including plants, algae, decaying organic matter, beach wrack and bird feces – implicating these as potentially significant contributors to exceedances (Imamura et al 2011, Izbicki 2012b). Beach sands, sediments and beach wrack have been shown to be capable of serving as reservoirs of bacteria, possibly by providing shelter from UV inactivation and predation by allowing for regrowth (Imamura et al 2011, Izbicki et al 2012b, Lee et al 2006, Ferguson et al 2005, Grant et al 2001, Griffith 2012, Litton et al 2010, Phillips et al 2011, Jiang et al 2004, Sabino et al 2011, and Weston Solutions 2010). In fact, enterococci include non-fecal or “natural” strains that live and grow in water, soil, plants and insects (Griffith, 2012). Thus, elevated levels of enterococci in water could be related to input from natural sources. The phenomenon of regrowth of bacteria from either anthropogenic or natural sources has been suggested by several studies as a possible source of beach bacteria exceedances (Griffith 2012, Litton et al 2010, Weston Solutions 2010, Izbicki et al 2012b, Weisberg et al 2009).”
In 2009, a dry weather bacterial source identification study was undertaken at the Redondo Beach Pier (Los Angeles County Sanitation District [LACSD], 2009). This study implemented a multi-tiered toolbox approach to investigate sources of dry weather fecal indicator bacteria (FIB) exceedances near Redondo Beach Pier (CSMP monitoring location SMB 6-02).). Utilizing microbial source tracking, the sampling focused on the shoreline near the pier, a storm drain under the pier, and ponded water near the storm drain. Investigators found a lack of human fecal markers within the surf zone:
“Lack of detectable human viruses and the de minimus quantities detection of humanassociated Bacteroidales in the ocean water strongly implied that a human source was not present. Other sources of FIB may include bacterial persistence in the sand and sea wrack, as well as endogenous sea life and birds. Tide, wave action, wind, and other natural fluctuations may be affecting FIB levels at the shoreline monitoring locations next to the pier.” However, the study also indicated that,
“…the storm drain under the pier and the pond that forms at the storm drain outlet are probably impacted by human fecal pollution but are not contributing to microbial contamination of the ocean water during the dry season. This conclusion is most strongly supported by the differences between the FIB concentrations and Bacteroidales populations at the shoreline sites compared to the pond and storm drain samples, particularly with respect to human-associated Bacteroidales.”

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Another dry weather MS4 microbial source tracking study was conducted in 2010, focusing on two high priority analysis regions (SMB-5-02 and 6-01) within the Beach Cities EWMP Area (Geosyntec Consultants, 2010). Although both of these shoreline monitoring locations are served by low flow diversions, the purpose of the study was to investigate FIB sources to inform identification of new source control measures. Observational results indicated that non-human sources include pet waste, irrigation runoff, and in-drain sources (i.e., re-growth, sediment, etc.). Similar to the Redondo Beach pier study, human Bacteroidales marker (HBM) was also identified in some MS4 dry weather samples, suggesting that human fecal sources may also be present. Although specific sources of human waste were not definitively identified in the study, “sources were surmised to include direct contamination (i.e., illicit connections, RV discharges, homeless deposits), and indirect contamination (i.e., sewer exfiltration).”9
To address the identification of dry weather bacteria sources within or to the MS4s, the Beach Cities WMG agencies have implemented measures to divert dry weather flows from all storm drains discharging at point zero shoreline monitoring locations. A total of seven low flow diversions are operational within the Beach Cities EWMP area. No wet weather bacteria source identification studies have been conducted in the Beach Cities EWMP area to date. Wet weather bacteria sources are believed to be derived from the entire watershed, and potentially include a mixture of human sources, non-human anthropogenic sources (e.g., pet waste), and non-anthropogenic sources (e.g., birds and other urban wildlife, storm drain biofilms/regrowth, beach sands and wrack). A wet weather stormwater monitoring study by the Southern California Coastal Water Research Project (SCCWRP) investigated bacteria concentrations in stormwater runoff from various land uses in the Los Angeles region (Stein et al, 2007). Results showed that wet weather runoff event mean concentrations (EMCs) for fecal coliform bacteria were highest for agricultural land uses, followed by commercial and educational, single family residential, multi-family residential, open space, industrial, and transportation. In this study, results showed that bacteria concentrations in stormwater are highly variable, with concentrations often varying by one to two orders of magnitude during a single storm, and by up to five orders of magnitude on seasonal and interannual scales.

Additional local monitoring data will be needed to quantify the contribution of MS4 discharges – particularly relative to the many other identified sources that have been documented along SMB beaches – to the elevated bacteria concentrations measured at Beach Cities WMG compliance monitoring locations during dry and wet weather. Additional data are also needed to identify the sources of bacteria within MS4 discharges as well as their potential to contribute to recreational illness risks; such source tracking data have the potential to affect the TMDL waste load allocations (WLAs) through a future reopener10. And the combination of MS4 outfall monitoring (through the

9 The LACSD and Geosyntec microbial source tracking studies predate the 2013 California Source Identification Pilot Project, which identifies and recommends new, more definitive microbial source tracking markers for multiple source types, including human waste. Therefore new analytical methods may need to be applied to these previously studied areas to verify or update prior findings. 10 For example, if human fecal sources are found to be undetected in MS4 discharges to SMB beaches using a rigorous sampling design, the latest analytical markers, and a credible laboratory, then TMDL revisions may be proposed.

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CIMP) and source identification (through special studies) could support future BMP planning and EWMP updates.

DDT and PCBs
As stated previously, limited data are available characterizing DDT and PCBs within Santa Monica Bay, particularly since direct discharges of these pollutants from publically owned treatment works (POTWs) have ceased. The largest concentration of DDT and PCBs within SMB is contained within the Palos Verdes shelf, which is being addressed by the USEPA as a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) site. Loadings from the shelf to the bay are large and have been well characterized (USEPA, 2012).

With respect to stormwater, the TMDL does not specifically characterize MS4 loadings, though it does recognize that “DDT and PCBs are no longer detected in routine stormwater sampling from Ballona Creek or Malibu Creek.” However, the TMDL also states that current detection limits used to analyze DDT and PCB concentrations are too high to appropriately assess the water quality.

Despite a lack of supporting data, however, EPA assumed that stormwater inputs of DDT and PCBs come from urban areas (USEPA, 2012).

No other data or source information are available at this time. Once three years of water quality data are collected under the CIMP and evaluated consistent with the recommendations by USEPA in the TMDL to utilize a three-year averaging period, then further source assessment will be considered and the categorization and prioritization of PCB and DDTs as MS4-related pollutants of concern will be reevaluated.

Trash
Source information for trash within SMB is provided by the SMB Nearshore Debris TMDL. A detailed source breakdown is not provided, but other debris TMDLs attribute trash to general areas such as “litter from adjacent land areas, roadways, and direct dumping and deposition” (LARWQCB, 2008) while also attributing trash inputs to point sources such as storm drains.

The plastic pellet portion of the SMB Debris TMDL is not applicable to the Beach Cities WMG, as the respective Agencies have applied and have gained approval to be exempt from this portion of the TMDL.

2.2.4 PRIORITIZATION
Based on the water quality characterization above, the WBPCs have been classified into one of three categories, in accordance with Section IV.C.5(a)ii of the Permit: highest priority, high priority, and medium priority (Table 2-3). This categorization is intended to prioritize WBPCs in order to guide the implementation of structural and institutional BMPs. An RAA was performed on the WBPCs in Categories 1, as there are no Category 2 or 3 pollutants in the SMB Watershed within the Beach Cities WMG. WBPCs will be further prioritized based on the applicable compliance schedules, as discussed in Section 4.

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2.3 SELECTION OF APPROPRIATE BEST MANAGEMENT PRACTICES

2.3.1 OBJECTIVES
The Permit requires the Beach Cities WMG to identify strategies, control measures, and BMPs to implement within their EWMP AREA. Specifically, the Permit specifies that BMPs are expected to be implemented so that MS4 discharges meet effluent limits as established in the Permit and to reduce impacts to receiving waters from stormwater and non-stormwater runoff. This expectation assumes the implementation of both types of BMPs – non-structural and structural – by the Beach Cities WMG.

The objectives of selecting and incorporating BMPs into the Beach Cities EWMP include:

1. Preventing and/or eliminating non-stormwater discharges to the MS4 that are a source of pollutants from the MS4 to receiving waters;

2. Achieving all applicable interim and final WQBELs and/or RWLs pursuant to corresponding compliance schedules; and

3. Ensuring that discharges form the MS4 do not cause or contribute to exceedances of RWLs.

2.3.2 DEFINITION OF BEST MANAGEMENT PRACTICES
The Permit defines BMPs as “practices or physical devices or systems designed to prevent or reduce pollutant loading from stormwater or non-stormwater discharges to receiving waters, or designed to reduce the volume of stormwater or non-stormwater discharged to the receiving water.” These BMPs may include:

1. Structural and/or non-structural BMPs and operation and maintenance procedures that are designed to achieve applicable WQBELs and/or RWLs;

2. Retrofitting areas of existing development known or suspected to contribute to the highest water quality priorities with regional or sub-regional BMPs;

3. Stream and/or habitat rehabilitation or restoration projects where stream and/or habitat rehabilitation or restoration are necessary for, or will contribute to demonstrable improvements in the physical, chemical, or biological receiving water conditions and restoration and/or protection of water quality standards in receiving waters.

Structural BMPs involve the construction of a physical control measure to alter the hydrology or water quality of incoming stormwater or non-stormwater. There are two categories of structural BMPs, defined by the runoff area treated by the BMP: regional BMPs 11 and distributed BMPs.

Regional BMPs are designed to treat runoff from a large drainage area expected to include multiple parcels and various land uses. These may include infiltration basins, treatment plants, and subsurface flow wetlands, among others. Distributed BMPs are designed to treat runoff from

11 The term “regional BMP” does not necessarily indicate that the project can capture and retain the 85th percentile storm, as described in the Permit. The term “regional EWMP project” is therefore used for those regional BMPs that are expected to be able to capture and retain the 85th percentile storm.

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smaller drainage areas and are normally installed to collect runoff close to the source from a limited number of parcels. Distributed BMPs typically include swales, bioretention facilities, biofiltration facilities, and cisterns, among others. Relevant regional and distributed structural BMPs are described below.

Non-structural BMPs prevent or reduce the release of pollutants or transport of pollutants within the MS4 area but do not involve construction of physical facilities. Non-structural BMPs are often implemented as programs or strategies which seek to reduce runoff and/or pollution close to the source. Examples include but are not limited to: street sweeping, downspout disconnect programs, pet waste cleanup stations, irrigation ordinances, or illicit discharge elimination. Minimum control measures (MCMs) as set forth in the Permit are a subset of non-structural BMPs even though some MCMs include measures that require the implementation of structural BMPs by private parties.

2.3.3 INCORPORATED PROVISIONS
Permit Section VI.C.5.b.iv sets forth the provisions regarding the types of BMPs that must be considered in development of the EWMP. These provisions are described in more detail below.

Minimum Control Measures
The Beach Cities WMG has assessed the MCMs defined in the Permit to identify opportunities for focusing resources on the high priority issues in each watershed. The Permit requires the permittees to implement prescribed MCMs in each of six categories/programs: Public Information & Participation Program (PIPP), Industrial/Commercial Facilities, Planning & Land Development, Development Construction, Public Agency Activities, and Illicit Connection & Illicit Discharges Elimination. These measures include procedures such as outreach programs, inspections, and reporting requirements designed to reduce runoff-related pollution within each permittees’ MS4 area. MCMs in each of these categories are already being implemented by the Beach Cities WMG as prescribed under the previous MS4 Permit (Order 01-182), and in some cases MCM program enhancements have been implemented to address watershed priorities for TMDL implementation.

Details on the selected MCMs, including proposed modifications to any programs, are provided in Section 2.6.2 (Santa Monica Bay Watershed) and Section 3.6.2 (Dominguez Channel Watershed).

Non-Stormwater Discharge Measures
The Permit requires Permittees to identify non-stormwater discharges that cause or contribute to exceedances of RWLs, and to then identify and implement BMPs to effectively eliminate the source of pollutants. These BMPs may include measures to prohibit non-stormwater discharge to the MS4, additional structural BMPs to reduce pollutants in the non-stormwater discharge, diversion to a sanitary sewer for treatment, or strategies to require the non-stormwater discharge to be separately regulated under a general NPDES permit. As previously stated, the Beach Cities WMG agencies currently operate seven low flow diversions along the Santa Monica Bay to eliminate nonstormwater discharges.

The non-stormwater screening process consists of the steps shown in Figure 2-4. Further details on the Beach Cities WMGs approach to meet this requirement are provided in the CIMP for the Beach Cities Watershed Management Group (Beach Cities Watershed Management Group, 2014).

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The watershed control measures proposed for non-stormwater discharges meet the requirements as set forth in Parts III.A and VI.D .4.d and VI.D.10 of the LA County MS4 Permit.

The following schedule is proposed to eliminate unauthorized non-stormwater discharges that are either causing or contributing to receiving water exceedances in Santa Monica Bay watershed:
• December 28, 2016—Source investigation will be completed on 50% of the major outfalls with significant non-stormwater discharges in the Beach Cities EWMP Area (including outfall SMBO-7). • March 28, 2017— Outfall monitoring will be initiated as required for the investigated outfalls, based on results of source investigation in accordance with Section 5.6 of the Beach Cities CIMP, to determine compliance with applicable non-stormwater WQBELs derived from TMDL WLAs. • June 26, 2017—Elimination of all significant, unauthorized non-stormwater contributions will be completed for the investigated outfalls.
• December 28, 2017—Source investigations will be completed on the remaining 50% of the major outfalls with significant non-stormwater discharges in the Beach Cities EWMP area, (source investigation will be 100% complete by this date). • March 28, 2018—Outfall monitoring will be initiated as required for the remaining 50% of investigated outfalls, based on results of source identification in accordance with Section 5.6 of the Beach Cities CIMP, to determine compliance with applicable non-stormwater WQBELs derived from TMDL WLAs.
• June 26, 2018—Elimination of all significant, unauthorized non-stormwater contributions will be completed for 100% of the major outfalls in the Beach Cities EWMP Area.

Source investigations will take place in accordance with Section 5.5 of the Beach Cities CIMP. Nonstormwater discharge elimination will be prioritized in Santa Monica Bay due to the fact that the dry weather final compliance date for the Santa Monica Bay Beaches Bacteria TMDL has passed.

TMDL-Specific Control Measures
The Beach Cities WMG has evaluated BMPs that have been previously identified in TMDLs and corresponding implementation plans. Those BMPs that have been constructed are discussed in Section 2.6.4 (Santa Monica Bay Watershed) and Section 3.6.4 (Dominguez Channel Watershed).

Other measures identified in TMDLs and TMDL implementation plans were evaluated as part of the RAA process in order to determine what combination of measures would achieve compliance with Permit-specified WQBELs and/or RWLs.

Additional BMPs
In addition to the MCMs, non-stormwater discharge measures, and TMDL control measures, the Beach Cities WMG has identified additional BMPs to achieve compliance with Permit-specified WQBELs and/or RWLs. These BMPs are discussed in more detail in Section 2.6 (Monica Bay Watershed) and Section 3.6 (Dominguez Channel Watershed) below.

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Demonstration of BMP Performance – Introduction to the Reasonable Assurance Analysis
The EWMP is a planning document intended to lay out a framework of activities that will comply with water quality requirements. Therefore, it is necessary to demonstrate that selected BMPs are reasonably expected to meet defined goals and objectives. This demonstration of performance is described through a technically robust and rigorous RAA. Through this analysis the Beach Cities WMG identified and evaluated BMP implementation scenarios within the Beach Cities EWMP Area for each WBPC identified in Section 2.2. The RAA process demonstrates that implementation of EWMP-defined activities should result in the attainment of applicable Permit-specified WQBELs, and will also prevent discharges from causing or contributing to exceedances of applicable RWLs.

Since the modeling conducted as part of the RAA serves as the basis not only for BMP evaluation but also BMP identification, Section 2.4 is devoted to providing details on the RAA process. Results from the RAA are presented in Section 2.7.

Legal Authority
The Permit-required legal authority that the Beach Cities WMG has to implement the BMPs identified in the EWMP is discussed in Section 8.

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Figure 2-4. Non-Stormwater Outfall Screening Program

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2.4 REASONABLE ASSURANCE ANALYSIS APPROACH
The following subsections provide a summary of the modeling tools and approach, modeling data, calibration, and validation.

2.4.1 DESCRIPTION OF RAA TOOLS AND APPROACH
The approaches for performing the RAA in both dry and wet weather are described below.

Dry Weather
Demonstrating “reasonable assurance” of compliance with dry weather limits for the SMBBB TMDL requires a methodology that accounts for many factors which cannot be accurately modeled based on urban runoff processes alone (Thoe et al, 2014), despite the extensive summer-dry and winterdry weather beach-specific monitoring datasets that are available. Therefore, to perform the RAA for dry weather for the Beach Cities WMG area, a semi-quantitative methodology has been developed to follow a permit compliance structure, as independent lines of evidence for demonstrating that MS4 discharges could not be causing or contributing to receiving water exceedances at the beaches. Because FIB are considered the “controlling” pollutants of concern during dry weather in the Beach Cities WMG area (i.e., if MS4 discharges are compliant for bacteria during dry weather, they will be compliant for all TMDL and 303(d) pollutants during dry weather), the methodology was developed to focus on bacteria (Beach Cities WMG, 2014).

The following criteria form the proposed dry weather RAA methodology. This methodology was presented to LARWQCB staff on April 9, 2014, and verbal feedback received at the time was supportive. If one criterion is met for CSMP compliance monitoring location (CML), then “reasonable assurance” is considered to be demonstrated.

1. A dry weather low flow diversion, disinfection system, or infiltration system is located at the CML. To meet this criterion, any such system should have records to show that it is consistently operational, well maintained, and sized to effectively eliminate freshwater surface discharges to the surf zone during year-round dry weather days.

2. There are no MS4 outfalls owned by the Beach Cities WMG Agencies within the CML’s drainage area, and therefore MS4 discharges could not be contributing to pollutant concentrations at the CML.

3. Non-stormwater MS4 outfall discharges do not reach the wave wash and thus are effectively eliminated within the CML’s drainage area. For this criterion to be met, supporting records from the non-stormwater outfall screening program should be supplied.

Wet Weather
The wet-weather RAA process consists generally of the following steps:
• Identify WBPCs for which the RAA will be performed;
• Identify the MS4 service area (exclude lands of agencies not party to this EWMP such as separately-permitted lands, Federal land, State land, etc.);

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• For each analysis region (Figure 2-5), develop target load reductions (TLRs) for 90th percentile year for bacteria in SMB watershed based on LARWQCB RAA Guidelines, limit expressions in the Permit, and critical periods identified in the TMDLs; • Identify structural and non-structural BMPs that were either implemented after applicable TMDL effective dates or are planned for implementation in the future; • Evaluate the performance of these BMPs in terms of annual pollutant load reductions; • Compare these estimates with the TLRs; and
• Revise the BMP implementation scenario until TLRs are met.

TLRs, as discussed previously, represent a numerical expression of the Permit compliance metrics (e.g., bacteria allowable exceedance days [AEDs] per year for wet weather) that can be modeled and can serve as a basis for confirming, with reasonable assurance, that implementation of the proposed BMPs will result in attainment of the applicable TMDL-based WQBELs and RWLs in the Permit for Category 1 pollutants, or the Water Quality Objectives for Category 2 and Category 3 pollutants.

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Figure 2-5. Analysis Regions and Monitoring Locations within the SMB Watershed portion of the Beach Cities EWMP Area

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Structural BMP Prioritization and Analysis Tool (SBPAT) Model The recommended RAA approach leverages the strengths of the publicly available, Permitapproved, Geographical Information System (GIS)-based model that has already been developed for the region and previously utilized in Jurisdictional Group 5 and 6 (J5&6): the Structural BMP Prioritization and Analysis Tool (SBPAT)12.

SBPAT is a public domain, “open source,” GIS-based water quality analysis tool intended to: 1) facilitate the prioritization and selection of BMP project opportunities and technologies in urbanized watersheds; and 2) quantify benefits, costs, variability, and potential compliance risk associated with stormwater quality projects. The decision to use SBPAT for the SMB EWMP RAA in the manner described below is based on the model capabilities and the unique characteristics of the SMB, specifically:

1. Modeling of SMB hydrologic and watershed processes – SBPAT utilizes EPA’s Stormwater Management Model (SWMM) as the hydrologic engine, and SBPAT has been calibrated to local rainfall and Santa Monica Bay (SMB) stream flow gauges, consistent with requirements of the RAA Guidelines;

2. SMB pollutants of concern and their compliance metric expression – SBPAT has been utilized for planning applications related to Bacteria TMDL compliance (and specifically exceedance-day predictions, based on SMB criteria), including a demonstrated linkage of modeled bacteria loads to measured exceedance days;

3. Availability of new open space water quality loading data – Recently developed EMC data are consistent with SBPAT and were also updated to reflect new data developed in SMB as part of this RAA-development effort;

4. Capability to conduct opportunity and constraints screening – SBPAT was designed to support structural BMP placement, prioritization, and cost-benefit quantification, and was previously successfully used for such purposes in the SMB EWMP Group area and other nearby SMB subwatersheds;

5. Characterization of water quality variability – SBPAT is capable of quantifying model output variability and confidence levels, which is a requirement of the LARWQCB’s RAA Guidance; and

6. Supports quantification of both structural and non-structural BMPs, and demonstrating compliance at both interim and final compliance dates – SBPAT’s modeling framework is easily compatible with methods for addressing non-structural BMPs and provides quantitative results for multiple BMP phasing milestones, as required by the Permit.

12 SBPAT is specifically referenced in the MS4 Permit Part VI.C.5.b.iv and was presented at the first two Permit Group TAC RAA Subcommittee meetings. Furthermore, SBPAT has been used for reasonable assurance analysis purposes in the Los Angeles region for four TMDL Implementation Plans, two WMPs, four EWMPs, and, in the San Diego region, for two Combined Load Reduction Plans and two Water Quality Improvement Plans.

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The quantification analysis component of SBPAT includes a number of features. The model:
• Calculates and tracks inflows to BMPs, treated discharge, bypassed flows, evaporation, and infiltration at each 10 minute time step;
• Distinguishes between individual runoff events by defining six-hour minimum inter-event time in the rainfall record (in order to track rain events), while also tracking inter-event antecedent conditions;
• Tracks volume captured by and bypassing BMPs, and summarizes and records these volumes by storm event; and
• Produces a table of each BMP’s hydrologic performance, including concentrations and loads by storm event, and consolidates these outputs on an annual basis.

2.4.2 MODELING DATA
Data used for the quantification/analysis module include both fixed and stochastic parameters. The model utilizes Los Angeles region land use EMCs, USEPA SWMM, USEPA/American Society of Civil Engineers/Water Environment Research Foundation (USEPA/ASCE/WERF) International BMP Database (IBD) BMP effluent concentrations, watershed/GIS data, and a Monte Carlo approach (relying on repeated random sampling) to quantify water quality benefits and uncertainties. Model data flow is provided below in Figure 2-6.

Figure 2-6. SBPAT Model Data Flow
Each model simulation integrates Monte Carlo methods that rely on repeated random sampling to obtain numerical results. Model simulations are run 20,000 to 50,000 times to calculate a distribution of outcomes that can support the definition of confidence levels and quantify variability. Consistent with the SBPAT usage, Monte Carlo methods are used in physical and mathematical problems when it is difficult to obtain a closed-form expression or when a

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deterministic algorithm is not desired. A schematic of SBPAT’s Monte Carlo process is provided in Figure 2-7.

Model documentation, as well as links to related technical articles and presentations, is provided at www.sbpat.net.

Figure 2-7. SBPAT Monte Carlo Method Components
The spatial domain of the RAA includes the land within the Beach Cities EWMP area tributary to SMB and Dominguez Channel. Adjustments were made to account for contributions from agencies not party to this EWMP (e.g., State/Federal, California Department of Transportation [Caltrans], Industrial General Permit holders, etc.) and are described in more detail later in this document.

GIS layers used in SBPAT included, but were not limited to, the following:
• Storm drains;
• Soils;
• Rain gauge polygons;
• Parcels;
• Land use; and
• Catchments.

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SBPAT utilizes a customized version of SWMM for continuously simulating study area hydrology and BMP hydraulics. Long‐term, hourly rainfall data and average monthly evapotranspiration values are used along with land use-linked catchment imperviousness and soil properties to estimate runoff volumes. Revised and recalibrated SBPAT database values and EWMP-defined BMP information are used to estimate the volume of runoff generated from watershed areas and captured by BMPs. Storm events are individually tracked for the entire simulation so that the volumes of runoff infiltrated, evapotranspired, captured, and released (if applicable) by BMPs are estimated for every storm event. Hourly rainfall data from LAX (NCDC ID45114) were used in the portion of the Beach Cities EWMP area draining to Santa Monica Bay. Hourly rainfall data from a Los Angeles County rainfall gauge at Manhattan Beach (Station ID 1070) was used for the portion of the Beach Cities EWMP area draining to Dominguez Channel. Rain gauges are shown in Figure 2-8.

Figure 2-8. SBPAT Rain and Stream Gauges
Critical Condition Definition
Consistent with the SMBBB TMDL and the LARWQCB RAA Guidance Document, the RAA was performed on the 90th percentile critical year. This year was determined by evaluation of local rainfall records for all four EWMP Groups located along Santa Monica Bay over the 1989 to 2011 period of record, evaluating “TMDL years” as defined by the SMBBB TMDL (i.e., November 1 –

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October 31). Of the local rain gauges evaluated, the Manhattan Beach gauge (Station ID 1070) (Figure 2-8), was determined to be the most representative of the Beach Cities WMG area. The rainfall record was analyzed to determine the 90th percentile year based on both the number of wet days (days with >=0.10-inch for rainfall and the three days following, per the SMBBB TMDL) as well as total annual rainfall. Table 2-5 below presents these results. The 90th percentile year was determined to be either 1995 or 2005 based on wet days (73 total). TMDL year 1995 was selected to be the most conservative of these two years because while it is the 90th percentile year based on number of wet days, 1995 also had slightly more total rainfall than 2005. Therefore, the RAA was performed on TMDL year 1995. Although detailed results are only provided for the Beach Cities WMG, the 90th percentile year was determined to be 1995 across all four SMB EWMP Groups (Santa Monica Bay, North Santa Monica Bay Coastal Watersheds, Beach Cities, and Peninsula). A summary of annual rainfall data for the gauge above is provided in Appendix Q.

Table 2-5. Rainfall Summary at Manhattan Beach Precipitation Gauge (Station ID 1070) 90th Percentile TMDL Year (Type) TMDL Year Wet Days* Total Rainfall (in) Number of Wet Days 1995 73 22.0
Total Annual Rainfall 2005 73 21.9
*Compliance with the wet weather SMBBB TMDL is based on the number of allowable exceedance days.

The priority WBPCs for the Beach Cities EWMP area, combined with data availability, establishes the specific WBPCs addressed by the RAA. As previously described, SBPAT links the long‐term hydrologic output from SWMM to a stochastic Monte Carlo water quality model to develop statistical descriptions of stormwater quantity and quality. Through this approach, the predicted runoff volumes for each storm are randomly sampled from the long‐term storm event runoff volume record produced by SWMM. Land use-based wet weather pollutant EMC values (see Appendix I) and BMP effluent concentrations (see Appendix J) for each storm are then randomly sampled from their lognormal statistical distributions. The runoff volumes (including volumes treated and bypassed by BMPs), land use EMCs, and BMP effluent concentrations are combined to determine the total pollutant loads and load reductions (i.e., difference between existing and post‐ BMP load estimates) for each sampled storm event. This procedure is then repeated thousands of times, each time recording the volume, pollutant concentrations, loads, and load reductions for each selected storm event. The statistics of these recorded results are then used to characterize the average daily values as well as the average (mean) values for the annual volume, pollutant loads, and pollutant concentrations in stormwater runoff from the modeled area, with and without BMPs implemented.

The IBD is a comprehensive source of BMP performance information (www.bmpdatabase.org), comprised of data from a peer-reviewed collection of studies that have monitored the effectiveness of a variety of BMPs in treating water quality pollutants for a variety of land use types. Water quality performance data from the IBD were used to develop effluent concentrations (averages and standard deviations) for the BMPs and constituents in Table 2-6. As with land use EMCs, the effluent quality of BMPs is highly variable. To account for this variability in SBPAT, effluent quality data were analyzed and descriptive statistics were generated for use in the Monte Carlo statistical sampling technique. Appendix J contains detailed information on the BMP effluent statistics.

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Table 2-6. BMPS and Constituents Modeled in SBPAT1
BMPs Constituents
Constructed Wetland / Retention Pond (with Extended
Detention)
Constructed Wetland / Retention Pond (without Extended
Detention)
Dry Extended Detention Basin
Hydrodynamic Separator
Media Filter
Subsurface Flow Wetland
Treatment Plant
Bioswale
Bioretention with underdrain
Bioretention (volume reduction only)2
Cistern (volume reduction only)2
Green Roof (volume reduction only)2
Porous Pavement (volume reduction only)2
Low Flow Diversion (volume reduction only)2
Fecal Coliform (FC)
Total lead (TPb)
Total suspended solids (TSS)
Total phosphorus (TP)
Dissolved phosphorus as P (DP)3
Ammonia as N (NH3)
Nitrate as N (NO3)
Total Kjeldahl nitrogen as N (TKN)
Dissolved copper (DCu)
Total copper (TCu)
Dissolved zinc (DZn)
Total zinc (TZn)
1 Constituents are addressed for BMPs that provide treatment (i.e., excluding those identified as “volume reduction only”).
2 For these BMPs, it is assumed that 100% of pollutant loads associated with the volume of water infiltrated is treated by the BMP. Water that bypasses or otherwise discharges from the BMP is assumed to receive no treatment.
3 Dissolved phosphorus and orthophosphate datasets were combined to provide a larger dataset and because the majority of orthophosphate is typically dissolved and many datasets either report dissolved phosphorus or orthophosphate, but not both.

2.4.3 CALIBRATION
Hydrology
The hydrology component of SBPAT was calibrated for the only location in the entire greater SMB watershed where all data requirements (daily flow, hourly precipitation, and daily beach bacteria concentrations) were met - the Topanga Creek subwatershed. No other SMB areas have sufficient data available. The Topanga Creek subwatershed is located north of the Beach Cities WMG area.

Since primary output for SBPAT’s prediction of the SMB watershed are annual volumes and pollutant loads, the calibration focused on accurate prediction of annual discharge volumes from the Topanga Creek subwatershed outlet, with estimated baseflow removed. Hourly rainfall data were used for the nearby Lechuza Patrol Station #72 gauge (gauge reference ID 352b, see Figure 2-8, in Malibu, with these data adjusted upward based on an annual rain depth ratio between the higher elevation Topanga Fire Station #69 gauge (gauge reference ID 6) and the coastal Lechuza gauge. Los Angeles County’s Topanga Creek streamflow gauge (gauge reference ID F54C-R) was used to estimate measured annual discharge volumes for comparison with modeled volumes. The effective impervious percentage for the open space land use category and the saturated hydraulic conductivity of all mapped soil types served as calibration parameters.

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Previous hydrologic calibration reported in the Beach Cities EWMP Work Plan (Beach Cities WMG, 2014) was refined to include additional precipitation and streamflow data. The refined calibration used a vacant undifferentiated land use effective imperviousness value of 1 percent. The refined calibration required the evaluation of various saturated hydraulic conductivity multipliers that would result in increased model runoff (i.e., each soil type’s original hydraulic saturated conductivity was multiplied by the same value). The calibration was performed iteratively with multipliers ranging from 0.1 to 2.0 until the average annual modeled volume produced an acceptable error value when compared to the average annual observed volumes. A multiplier of

0.20 was selected as most appropriate. Figure 2-9 is a depiction of the refined hydrologic calibration results, including the 0.20 saturated hydraulic conductivity multiplier. The emphasis of the calibration effort focused on accurate, unbiased prediction of “non-extreme” annual conditions (annual volumes exceeding a 25-year frequency, 4 percent probability, were excluded from the calibration effort). Based on available data, the period of calibration was 12 years, between 2001 and 2012, with water years 2005 and 2008 excluded due to outlying streamflow measurement results13. These calibrated input parameter values were used throughout the SMB watersheds in the wet weather RAAs. Figure 2-10 presents these same results in a flow duration curve format, which compares the distribution of annual discharge volume magnitudes throughout the period analyzed between the modeled and observed data.

Figure 2-9. Annual Runoff Volumes for Topanga Creek Subwatershed: Modeled vs.

Observed.

13 The stream gauge annual volume measurement in 2008 was unexplainably high (corresponding to a runoff coefficient greater than one), and the 2005 year included a 15-day period of near-record rainfall levels that were anomalously high (where the mean annual rainfall depth fell between December 27 and January 10, and major landslides were reported in coastal Ventura County). 0 1,000
2,000
3,000
4,000
5,000
6,000
0 1,000 2,000 3,000 4,000 5,000 6,000
Annual Modeled Flows After Calibration
(acre-ft)
Topanga Annual Observed Flows (no baseflow) (acre-ft)

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Figure 2-10. Annual Runoff Volumes for Topanga Creek Subwatershed: Modeled vs.

Observed (Flow Duration Curve Format).

Following calibration, average relative prediction error (or the percent differences between the average annual observed and modeled annual runoff volume) was calculated to be -0.24%.

According to the LARWQCB’s RAA Guidance Document, which is based on Donigian, 2000, SBPAT model performance with respect to hydrology as a result of this calibration is in the “very good” category.

Water Quality
The RAA Guidelines require water quality calibration based on available monitoring data from each analysis region over the most recent 10 years. However, in the SMB EWMP analysis regions, freshwater (i.e., mass emission type) monitoring stations with fecal coliform data 14 are not available from a recent 10 year period. Therefore, calibration that meets the guidelines is not possible at this time. After several years of CIMP monitoring data have been collected, this may be reevaluated as part of the EWMP adaptive management process. Also, since a conventional water quality calibration was not possible at this time, a validation of baseline exceedance day output was performed for the Leo Carrillo reference watershed using recent beach bacteria monitoring results, as described below. The reference watershed was used for this validation because it is the basis of the TMDL Waste Load Allocations, which the RAA TLRs are intended to represent.

14 Fecal coliform data and objectives were used to represent all fecal indicator bacteria because fecal coliform has the most robust land use and BMP effluent EMC datasets. 0 1,000
2,000
3,000
4,000
5,000
6,000
0 10 20 30 40 50 60 70 80 90 100
Annual Runoff Volume (ac-ft)
Percent of Results Below Y-Axis Value (%)
Measured Data (No Baseflow) - LACDPW Gauge ID F54C-R Modeling Output

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2.4.4 VALIDATION
A validation step was performed to demonstrate that modeled annual fecal coliform loads are indeed predictive of the compliance metric, or annual exceedance days for fecal indicator bacteria.

For bacteria modeling, verifying the linkage between modeled fecal coliform loads (i.e., discharged from the watershed outlets) and total observed wet weather exceedance days (in the receiving water, based on REC1 daily maximum water quality objectives) was critical to establish reasonable assurance that CMLs would be in compliance with the Permit limits. To establish this linkage, an analysis was conducted using shoreline monitoring data at Topanga Canyon15 (SMB-1-18) between 2005 and 2013. Figure 2-11 illustrates that decreasing fecal coliform loads should result in measurable reductions in exceedance days, and that there is a reasonable correlation between total annual modeled fecal coliform loads and total annual observed wet weather exceedance days. Each point shown represents one TMDL year.

Figure 2-11. Correlation between Modeled Fecal Coliform Loads and Observed Exceedance Days (each point represents one TMDL year, 2005-2013)

2.5 BASELINE LOADS AND TARGET LOAD REDUCTIONS
The process for establishing TLRs for the modeled WBPC (bacteria in Santa Monica Bay) is described in the following section. For analysis regions with SMBBB TMDL CMLs that have antidegradation-based allowable exceedance days for wet weather, a target load reduction of zero was

15 This subwatershed is 88 percent open space and was selected for water quality validation due to it being the hydrologic calibration subwatershed as well as because it had daily shoreline monitoring data, which was necessary in order to have a sufficiently robust dataset of annual wet weather exceedance days.

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assumed consistent with the TMDL’s approach which acknowledges that historic bacteria exceedance rates for each of these analysis regions are lower than that of the reference beach, on average. This assumption of zero target load reduction applies for seven of the 11 total SMBBB TMDL CMLs in this Beach Cities watershed – i.e., SMB-5-1, SMB-5-3, SMB-5-4, SMB-5-5, SMB-6-2, SMB-6-5, and SMB-6-6. Historic wet weather monitoring data (2005 – 2013) at these sampling locations confirm this understanding, as the long-term exceedance rate at all seven sites varies between 6.4 and 22%, below the long-term wet weather exceedance rate at the reference beach (26%). Bacteria reductions were still modeled using SBPAT in these analysis regions, but BMP modeling results were not compared with a target load reduction; i.e., quantification only serves to express the additional water quality benefits of existing and proposed BMPs in these analysis regions.

2.5.1 BACTERIA
In order to establish a TLR for each modeled Santa Monica Bay analysis region, a modeling methodology was developed and tested to relate the annual number of modeled calendar days with rainfall-generated runoff (or “discharge days”) to the expected annual bacteria exceedance days, which is the Permit’s WQBEL expression for the SMBBB TMDL. To be consistent with the SMBBB TMDL for wet weather, which established the allowed exceedance day Waste Load Allocations based on monitoring results from the Leo Carrillo reference beach, this modeling methodology was first tested on Leo Carrillo and its Arroyo Sequit subwatershed for the same critical year as the TMDL (TMDL year 1993). The goal of this analysis was to validate the modeling methodology by comparing its predicted exceedance days for Leo Carrillo with the 17 exceedance days from the TMDL, for TMDL year 1993. This analysis occurred in three steps:

1. The calibrated SBPAT model, using the nearby Lechuza Patrol Station gauge for TMDL year 1993 (consistent with the TMDL), resulted in 59 discharge days for Arroyo Sequit.

2. Based on 2003 to 2013 Leo Carrillo monitoring data, 27% of wet weather samples exceeded the single sample recreational Water Quality Objectives on days with rainfall greater than

0.10-in. In other words, 27% of wet weather days when runoff discharges might be expected (i.e., days with rainfall), FIB concentrations at the beach exceeded the objectives.

3. Multiplying 59 discharge days by the 27% exceedance percentage results in 16 predicted wet weather exceedance days for Leo Carrillo for TMDL Year 1993. This result is within 6% of the 17 exceedance days that were determined through the original analysis in the SMBBB wet weather TMDL, thereby validating the proposed exceedance day calculation methodology.

After validation of the modeling methodology using the reference watershed, it was applied to all SMB analysis regions to predict baseline exceedance days for the 90th percentile year, or TMDL year 1995. Once baseline exceedance days were estimated for every analysis region, the exceedance day count was compared with allowed exceedance days from the TMDL (i.e., 17 for all non-antidegradation compliance monitoring beaches). To determine the TLR necessary for each analysis region to meet the allowed exceedance days, a virtual retention BMP was modeled at the outlet of

Beach Cities EWMP | Section 2 | Santa Monica Bay Wate rshed 2-36 | Page 201 8
each analysis region. This approach was presented to LARWQCB staff on June 6, 2014 and verbal feedback received during the meeting was supportive.

Each virtual retention BMP included a diversion with a virtual hydraulic capacity that results in in a model-derived bypass frequency (or number of discharge days), during TMDL year 1995 that meets the allowable exceedance day criteria. Each diversion is modeled as a full capture system.

The net load reduction resulting from this BMP scenario (i.e., baseline analysis region load minus analysis region load with the diversion system and retention BMP in place) for the 90th percentile year (1995) becomes the TLR for each analysis region. For the RAA, reasonable assurance of compliance is established when load reductions associated with proposed BMPs equal the TLR for each analysis region.

In summary, the following approach was implemented to calculate a TLR for each modeled analysis region (see Appendix K for example calculation):

1. Each analysis region was modeled in SBPAT for the 90th percentile year (TMDL 1995).

2. The existing, baseline condition (i.e., without any outlet retention BMP) was modeled for each analysis region, resulting in a mean baseline fecal coliform (FC) load for the 90th percentile year (baseline load).

3. The exceedance percentage of samples collected during days with precipitation greater than 0.1 inches was determined for each analysis region.

4. The allowable number of discharge days for each analysis region was calculated by dividing 17 TMDL allowable exceedance days by the exceedance percentage calculated in Step 3.

5. An instream diversion to a large virtual retention BMP at the outlet of each analysis region was iteratively sized so that it only bypasses during the number of allowable discharge days determined in Step 4.

6. Each diversion and virtual retention BMP was then modeled in SBPAT to produce a mean FC load for the 90th percentile year (allowed load).

7. For each analysis region , the difference between the baseline load (step 2) and the allowed load (step 6) resulted in a TLR for the 90th percentile year, which was the target load reduction required to meet the 17 allowable TMDL exceedance days for wet weather.

By implementing the steps described above, TLRs were developed for all analysis regions within the MS4, including both open beach and point zero CMLs. These TLRs are presented in Table 2-7 for both the interim and final compliance deadlines. TLRs for the interim compliance deadlines are assumed to be 50% of the final TLR. TLRs for analysis regions located between two point zero CMLs, but not representing an open beach site, were assigned the TLR of the geographically smaller of the two adjacent CML analysis regions.

It should be noted that a zero percent TLR was calculated in the analysis region draining to CML SMB-6-03. This analysis region and CML had a lower average wet weather exceedance rate than the reference watershed based on a recent nine year period (2005-2013), produced relatively few modeled stormwater discharge days, and had few years with measured wet weather exceedance

Beach Cities EWMP | Section 2 | Santa Monica Bay Wate rshed 2-37 | Page 201 8
days greater than allowable exceedance days (i.e., only three of the recent nine years exceeded the allowed days, and each year by just one exceedance day).

Similarly, a zero percent TLR was also calculated in the analysis region draining to CML SMB-6-04.

The frequency of exceedance at SMB-6-04 (27.6%) was lower than that of the surrounding antidegradation sites SMB-6-02 (33.3%) and SMB-6-05 (31.0%) and also lower than the exceedance rate of SMB-6-03 (37.9%), which was calculated to have a TLR of zero. Further, SMB-6-04 is an open beach CML with no major MS4 outfall at the sampling location.

As stated earlier, nine CMLs with anti-degradation-based wet weather allowable exceedance days were assigned zero TLRs to reflect their historic good water quality. Although the SMBBB TMDL requires only that beach water quality at anti-degradation compliance locations be maintained, the Beach Cities EWMP will seek to implement nonstructural and Low Impact Development (LID)- based BMPs within the SMB portion of their EWMP area which will protect and potentially improve water quality at these beaches and is consistent with the J5&6 Implementation Plan (Geosyntec Consultants, 2011) for the SMBBB TMDL. These measures, though not required for RAA demonstration, are quantified in Section 2.6.3 below.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-38 | Page 2018
Table 2-7. Target Load Reductions for Fecal Coliform for each Modeled Analysis Region in Santa Monica Bay Watershed - TMDL Year 1995 Analysis Region
2003-2013
Historical
Exceedance
Frequency
Allowable
Discharge
Days
Diversion
Flowrate
(cfs)
Baseline Condition for the Critical Year Allowed Condition for the Critical Year6 Target Load Reduction for the Critical Year6 Annual
Runoff
Average
Pollutant
Concentration5
Annual
Pollutant
Load Annual Runoff
Average Pollutant
Concentration5
Annual Pollutant
Load
Interim Target Load
Reduction Final Target Load Reduction
(Daily Rainfall
>0.10-in)
(Daily Rainfall
> 0.10-in) (ac-ft)
(MPN/
100mL) (1012 MPN) (ac-ft)
(MPN/
100mL) (1012 MPN)
Absolute
Load
% of
Baseline
Annual Load
Absolute
Load
% of
Baseline
(1012 MPN) (1012 MPN) Annual Load
SMB-5-011 10.3% 4 0 39 15,400 7.4 39 15,400 7.4
Interim target load
reduction assessed on a
watershed-wide basis
0 0%
SMB-O-06 N/A 4 0 90 20,700 23.0 90 20,700 23.0 0 0%
SMB-5-02 67.9% 17 53 1516 28,600 534.8 1516 15,400 287.2 247.6 46.3% SMB-5-02/
SMB-5-032 N/A 12 0 123 23,000 34.9 123 23,000 34.9 0 0% SMB-5-031 17.2% 6 0 65 36,200 29.0 65 36,200 29.0 0 0%
SMB-5-03/
SMB-5-042 N/A 9 0 251 28,800 89.3 251 28,800 89.3 0 0%
SMB-5-041 31.0% 12 0 51 27,200 17.1 51 27,200 17.1 0 0% SMB-5-04/
SMB-5-052 N/A 10 0 37 17,800 8.2 37 17,800 8.2 0 0%
SMB-5-051 31.0% 8 0 472 31,400 182.8 472 31,400 182.8 0 0% SMB-5-05/
SMB-6-012 N/A 13 0 36 15,100 6.7 36 15,100 6.7 0 0%
SMB-6-013 63.9% 17 70 2118 27,100 706.6 2118 15,100 394.3 312.1 44.2% BCSump3 63.9% 17 40 1191 25,800 379.4 1191 13,700 201.4 178 46.9% SMB-6-01/
SMB-6-022 N/A 16 0 621 21,200 162.5 621 21,200 162.5 0 0% SMB-6-021,4 33.3% 14 0 358 22,600 99.6 358 22,600 99.6 0 0% SMB-6-03 37.9% 17 0 206 24,500 62.2 206 24,500 62.2 0 0% SMB-6-04 27.6% 17 0 621 27,400 209.9 621 27,400 209.9 0 0% SMB-6-051 31.0% 11 0 230 32,000 90.9 230 32,000 90.9 0 0% SMB-O-08 N/A 7 0 425 26,500 138.9 425 26,500 138.9 0 0% SMB-6-061 10.3% 3 0 19 28,000 6.7 19 28,000 6.7 0 0%
SMB WatershedWide N/A N/A N/A 8468 26,700 2789.9 8468 19,600 2052.1 368.9 13% 737.7 26% 1 Anti-degradation site. 2 For the unmonitored tributary areas located in-between the CML tributary areas, TLRs were assigned from the geographically smaller of the two adjacent CML analysis regions. 3 “BCSump” was defined as a separate analysis region for modeling purposes. The baseline load for “BCSump” analysis region was combined with the baseline load of the “SMB-6-01” analysis region to equal the total baseline load contributing to the SMB-6-01 CML (“SMB-6-01+BCSump”). 4 The drainage area to Outfall SMB-O-07 is encompassed by analysis region SMB-6-02; therefore SMB-O-07 was analyzed as part of analysis region SMB-6-02. 5 Average pollutant concentrations are estimated as the total annual load divided by the total annual runoff volume. 6 RAA demonstration is made based on the achievement of the TLR values in terms of absolute load removed by the proposed suite of BMPs in each analysis region. The target load reductions in terms of runoff volume and concentration are shown for informational purposes only.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-39 | Page 201 8

2.6 BEST MANAGEMENT PRACTICES

2.6.1 METHODS TO SELECT AND PRIORITIZE BMPS
In order to demonstrate reasonable assurance, BMPs were identified in a prioritized manner.

Prioritization was based on cost (low cost BMPs were prioritized first); BMP effectiveness for the pollutants of concern (BMPs that had greater treatment efficiency for the pollutant of concern in a particular analysis region were prioritized over other BMPs); and implementation feasibility as determined by the Beach Cities WMG. In general, nonstructural BMPs were prioritized over structural BMPs due to their lower relative cost, and then structural BMPs were identified that would likely result in the greatest load reduction per dollar.

The RAA was performed according to the following steps:

1. Calculate load reductions associated with existing structural BMPs;

2. Assume a load reduction for non-modeled non-structural BMPs (five percent of baseline pollutant load);

3. Calculate load reductions for public retrofit incentives (e.g., downspout disconnects) and redevelopment;

4. Calculate load reductions attributable to anticipated new permit compliance activities of non-MS4 entities (e.g., Industrial General Permit holders and Caltrans);

5. Calculate load reductions for proposed regional BMPs that were identified in existing plans; and

6. Meet the TLR by backfilling the remaining load reduction with new regional or distributed green streets BMPs, with green streets modeled by assuming treatment of runoff from a percentage of specific developed land uses.

The following schedule assumptions were made:
• Only BMPs implemented after the TMDL effective date (2003) were included; • Redevelopment BMPs were assumed to use different sizing criteria before and after 2015 (EWMP submittal date), consistent with the Permit’s post-construction requirements; and • Modeled load reduction output are reported for both the interim (2018) and final (2021) TMDL compliance dates.

2.6.2 RECOMMENDED MCMS AND NONSTRUCTURAL BMPS
The Permit allows permittees developing an EWMP the opportunity to customize the MCMs specified in the Permit to focus resources on high priority issues within their watersheds.

Modifications to the MCMs must be appropriately justified and still be consistent with 40 CFR § 122.26(d)(2)(iv)(A)-(D). A control measure may only be eliminated based on the justification that it is not applicable to a particular permittee (per Section IV.C.5.b.iv.1(c). Customized measures, once approved as part of the EWMP, will replace in part or in whole the prescribed MCMs in the Permit.

The Planning & Land Development Program is not eligible for customization in that it may be no

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-40 | Page 201 8
less stringent than the baseline requirements in the Permit. However, it can be enhanced over the baseline permit requirements if desired. The Permit-specified MCMs (baseline MCMs) build upon the MCMs in the previous MS4 Permit (Order 01-182). Although similar in many ways to the previously required MCMs, in most cases the baseline MCMs contain more prescriptive recordkeeping and/or implementation requirements.

Summary assessments of each MCM contained in the Permit are provided in Table 2-8, as well as a determination as to whether the Beach Cities WMG will implement the MCM provisions as defined in the Permit, or whether modifications will be made. Additional modifications may also be made through the Adaptive Management Process, outlined in Section 5.

General Framework for MCM Customization
An approach for evaluating existing institutional MCMs was developed as part of the Beach Cities EWMP Work Plan and was used to evaluate existing MCMs and develop the customized MCMs. The following steps provide a general framework for MCM customization:

1. Identify MCMs for potential customization. This may include identifying:
a. MCM requirements prescribed by the Permit which are not already being implemented by the permittee;
b. Currently implemented MCMs which have been enhanced over the previous Permit as part of TMDL implementation, e.g., Clean Bay Restaurant Program; c. Programmatic solutions/non-structural controls identified in TMDL implementation plans which may not yet have been implemented; and
d. MCMs which are currently being implemented but which may be excessive in scope.

For example, commercial inspections being conducted of retail gasoline facilities which are already heavily regulated through other environmental programs in areas that have no receiving water impairments for the pollutants of concern may be carried out less frequently, or discontinued indefinitely.

2. Identify MCMs which are not applicable. A control measure may be eliminated based on the justification that it is not applicable to a particular permittee. For example if it is the policy of a permittee not to use pesticides in public agency activities, then there is no need for tracking of pesticide use and this MCM may be proposed for elimination.

3. Assess the effectiveness of the incremental baseline MCM requirements with respect to water quality priorities. The data necessary to quantify this will vary greatly by MCM, but may include information such as: receiving water quality, inspection and reporting records, number of qualifying projects (e.g., number of construction projects greater than 1 acre), number of pet station bags used, amount of material picked up by street sweeping activities, number of employees trained, and maintenance records. Additionally, the California Stormwater Quality Association (CASQA) provides a tool to estimate the effectiveness of stormwater management programs (CASQA, 2015). The tool recommends possible assessment metrics that can be used for various stormwater programs.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-41 | Page 201 8

4. Quantify the additional resources required to implement the incremental baseline MCMs.

This may include estimating additional staff resources in terms of full-time employees, consulting resources, and contracted services.

5. Assess the effectiveness and resources required to implement the customized MCM. The process to quantify these will be the same as the process used to quantify the baseline effectiveness of the existing MCM.

6. Compare the assessed effectiveness and resources required to implement the incremental baseline MCMs and the customized MCMs. Customization can be justified in several ways:
a. If the customized MCM effectiveness is equal to or greater than the baseline MCM, customization can be justified.
b. If an MCM requirement is not applicable, then elimination is justified. c. If the incremental MCM requires additional resources that are disproportionate to the increased effectiveness achieved, then retention of the existing MCM may be justified.

7. Document the customized MCM justification.

MCMs were evaluated based on their effectiveness in addressing the WBPCs specific to the Beach Cities EWMP Area and based on the Beach Cities WMGs knowledge and experience with existing MCMs. In many ways, the Group’s practical experience with MCM implementation over time provides the best insight as to what MCM modifications/ enhancements will be most helpful to target the WBPCs of concern in the Beach Cities EWMP Area.

Table 2-8 summarizes the proposed MCM modifications common to the Beach Cities EWMP WMG, which include promotion of Ocean Friendly Landscaping Workshops as part of the residential outreach permit requirement, distribution of a Clean Bay Restaurant Program brochure to promote public education, establishment of a stormwater website for J5&6, implementation of the Clean Bay Restaurant Program as an assistance program for small businesses, and annual restaurant inspection as commercial pollutant sources. The LACFCD will implement the MCMs identified in VI.D.44 of the MS4 Permit with no additional modifications.

In addition to the MCM modifications being implemented by the WMG as a group, the Beach Cities WMG has identified additional individual city-specific MCM enhancements, which include organization of educational and cleanup-oriented events, installation of pet waste collection stations as a part of the residential outreach requirement, a ban on plastic bags in Manhattan Beach and polystyrene food containers in Hermosa Beach, and development of environmentally oriented city websites. City-specific MCMs enhanced beyond the 2012 Permit requirements are specified in Table 2-8. Details and descriptions of these enhancements are provided in Appendix L. The MCM enhancements shown in Table 2-8 and Appendix L are examples and are not comprehensive. The Beach Cities WMG agencies’ LID Ordinances and Green Street Policies are included as Appendix M and Appendix N, respectively.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-42 | Page 201 8
Table 2-8. MCM Modifications and Agency-Specific Enhancements for Beach Cities EWMP Area 2012 Permit Requirement
Baseline
Requirement
Maintained by
all Cities
General Beach
Cities MCM
Enhancement
(all Cities)
City-Specific MCM Enhancement
City of Manhattan Beach City of
Redondo Beach
City of
Hermosa Beach City of Torrance
MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented?
D.2 Progressive Enforcement (Applies D.6, D.7, D.8, and D.10) Develop and maintain a Progressive Enforcement Policy X X Milestone: 1/1/2016 Conduct follow-up inspection within 4 weeks of date of
initial inspection X
Take progressive enforcement X X Milestone: 1/1/2016
Retain records X
Refer violations to LARWQCB X
Investigate complaints from LARWQCB X
Assist LARWQCB with Enforcement Actions X
D.5 Public Information and Participation Program (PIPP) Participate in a Countywide PIPP, WMP PIPP, or
individual PIPP that measurably increases knowledge
and changes behavior, and involves a diversity of socio economic and ethnic communities
X X Implemented
Maintain reporting hotline X X Implemented
Publish hotline info on web, telephone book X
ID staff/department that serve as the contact (publish
this info) X
Organize events (e.g., clean ups) X X X Implemented X Implemented X Implemented X Implemented Residential Outreach (Individually or with group): X X X Implemented X Implemented X Implemented X Implemented Public Service Announcements X X X Implemented X Implemented X Implemented (Develop) Public education materials on: vehicle fluids; household waste; construction waste; pesticides,
fertilizers, and integrated pest management (IPM); green wastes; and animal wastes
X X
Implemented except
for IPM materials
(Milestone of June
2017 for IPM)
X
All except IPM are
implemented
(Milestone of June
2017 for IPM
materials)
X Implemented
Distribute public education materials at points of
purchase X X X Implemented X Implemented X Implemented
Maintain stormwater website X X X Implemented X Implemented X Implemented Provide schools with materials to educate children (K12); can use state produced materials X X Implemented X Implemented X Implemented D.6 Industrial/ Commercial
Track Critical Sources - maintain inventory (watershed
based or lat/long recorded) X
Educate - notify critical sources of BMP requirements X Implement a Business Assistance Program for select
sectors or small businesses - technical assistance, and distribute materials to specific sectors
X X X Implemented X Milestone: 1/1/2016
Inspect Commercial Sources X X X Implemented
Inspect Industrial Sources - Initial mandatory inspection X N/A N/A X Implemented Secondary mandatory inspection X N/A N/A

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-43 | Page 201 8
2012 Permit Requirement
Baseline
Requirement
Maintained by
all Cities
General Beach
Cities MCM
Enhancement
(all Cities)
City-Specific MCM Enhancement
City of Manhattan Beach City of
Redondo Beach
City of
Hermosa Beach City of Torrance
MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented?
No Exposure - evaluate and conduct 2nd inspection at
25% of facilities X N/A N/A
As needed, conduct Progressive Enforcement follow-up
inspections (see Part VI.D.2) X
D.7 Planning and Land Development
Update ordinance/design standards to conform with new
requirements (LID) X X
Implemented LID
ordinance enhanced
beyond permit
minimum
X Implemented
Optional: Establish alternative compliance for technical infeasibility, e.g., allow onsite biofiltration or offsite infiltration or groundwater replenishment or retrofit
X
Optional if allowing offsite mitigation: Develop a
prioritized list of offsite mitigation projects X
Optional if allowing offsite mitigation: Develop a
schedule for completion of offsite projects (must be with 4 yr of the Certificate of Occupancy of the first project that contributed funds)
X
Optional if allowing offsite mitigation: Notice offsite projects to RB website X
Optional if allowing offsite mitigation: List of mitigation projects descriptions and estimated pollutant and flow
reductions
X
Optional if allowing offsite mitigation: Provide
aggregated comparison of alternative compliance to
results that would have been expected with on-site
retention of the SWQDv
X
Optional: Submit documentation that a previously
adopted LID ordinance provides equivalent pollutant
loading and flow reduction
X
Plan Review process - check LID and BMP sizing, etc., X X Implemented X Implemented X Implemented Establish internal agreements with structure for
communication and authority for departments
overseeing plan approval and project construction
X
Require O&M plan for LID, treatment and hydromod
BMPs X
Implement tracking and enforcement program for LID,
treatment and hydromod BMPs X
Inspect all development sites upon completion and prior to occupancy certificates X
Verify O&M of BMPs operated by Permittee through
inspection X
Develop maintenance inspection checklist X
Require private parties that operate BMPs to submit
verification of O&M; enforce as needed X

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-44 | Page 201 8
2012 Permit Requirement
Baseline
Requirement
Maintained by
all Cities
General Beach
Cities MCM
Enhancement
(all Cities)
City-Specific MCM Enhancement
City of Manhattan Beach City of
Redondo Beach
City of
Hermosa Beach City of Torrance
MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented?
As needed, conduct Progressive Enforcement follow-up
inspections (see Part VI.D.2) X
D.8 Development Construction Program
Update erosion and sediment control
ordinance/procedures to conform with new
requirements
X X
Implemented
X Implemented
Sites < 1 acre; inspect based upon water quality threat X X Implemented Establish priority inspection process X X Implemented
Site < 1 acre; Require sites with soil disturbing activities to implement minimum BMPs X
Require construction sites to prepare erosion sediment
control plan(ESCP); review and approve (≥ 1 acre) X
Verify construction sites coverage under the CGP and 401 cert
X
Develop/implement ESCP review checklist X
Require construction sites to adhere to standards and
make standards readily available X
Conduct inspections at public and private sites (at least 1x/2 weeks for high threat sites (more frequently when
rain is predicted or occurs; at least monthly for lower threat; also must inspect during all phases of
construction - at least 3 times)
X
Develop/implement SOPs/inspection checklist X
Track number of inspections for inventoried sites and
verify minimum inspections are completed X
As needed, conduct Progressive Enforcement follow-up
inspections (see Part VI.D.2) X
Train plan review staff and inspectors X X Implemented X Implemented Staff must be knowledgeable in QSD/P key objectives,
local BMPs standards X
D.9 Public Agency Activities
Require public construction sites to implement Planning and Land Development requirements, implement Erosion
and Sediment Control BMPs, and obtain Construction
General Permit coverage
X X Implemented
Maintain inventory of Permittee owned facilities
(including parks and recreation facilities,) X
Update inventory X
Develop retrofit opportunity inventory; evaluate and
rank X X Implemented X Milestone: 1/1/2016
Cooperate with private land owners to encourage site
specific retrofitting; includes pilot projects and outreach X Obtain IGP coverage for public facilities where
appropriate X

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-45 | Page 201 8
2012 Permit Requirement
Baseline
Requirement
Maintained by
all Cities
General Beach
Cities MCM
Enhancement
(all Cities)
City-Specific MCM Enhancement
City of Manhattan Beach City of
Redondo Beach
City of
Hermosa Beach City of Torrance
MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented?
Develop procedures to assess impact of flood mgmt.
projects on water quality of receiving waters; evaluate to determine if retrofitting is feasible
X
Evaluate existing structural flood control facilities to determine if retrofitting facility to provide additional pollutant removal is feasible
X
Implement source control BMPs at Permittee owned
facilities/activities X
Require city-hired contractors to implement source
control BMPs X
Prevent vehicle/equipment washing discharges to the
MS4, including firefighting and emergency response
vehicles
X X
Implemented
Ensure new/redeveloped/replaced wash facilities are
plumbed to the sanitary sewer or self-contained. X
Implement IPM program X X Implemented
Ordinances, policies, and procedures reflect IPM
techniques and include commitments and schedules to
reduce the use of pesticides that cause impairments
X X
Implemented
Annually update in inventory of pesticides used by
agency; quantify pesticides used by staff and contractors; demonstrate IPM alternatives to reduce pesticide use
X X
Implemented
Use SOPs for pesticide application X X Implemented
Ensure no application of pesticides or fertilizers when two or more days with a 50% chance of rain is predicted by NOAA; within 48 hr of 1/2 inch of rain; or when water is flowing off the site
X
Ensure staff applying pesticides are certified or working under supervision of a certified applicator in the
appropriate category
X
Update catch basin map add GPS locations and update
priority X
Inspect/Clean catch basin in areas not subject to Trash TMDL- Priority A: 3x during wet season, 1x during dry
1x; Priority B: 1x during wet 1x and 1x during dry;
Priority C: 1x per yr. Maintain records.

X
Required trash management at public events X X Implemented X Implemented Place and maintain trash receptacles/capture devices at newly identified high trash generating areas X X Implemented X Implemented X Implemented X Implemented Label storm drains X X Implemented
Inspect labels prior to each wet season X
Record and relabel illegible labels within 180 days of
inspection X
Post signs at access points to water bodies (open
channels, creeks; lakes) X

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-46 | Page 201 8
2012 Permit Requirement
Baseline
Requirement
Maintained by
all Cities
General Beach
Cities MCM
Enhancement
(all Cities)
City-Specific MCM Enhancement
City of Manhattan Beach City of
Redondo Beach
City of
Hermosa Beach City of Torrance
MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented?
In areas not subject to the Trash TMDL, install trash
excluders on catch basins or outfalls in areas defined as Priority A, or implement substantially equivalent BMPs
X X Implemented X Implemented X Implemented X Milestone: 1/1/2016 Inspect and Remove trash and debris from open channels
and other drainage structures 1x/yr before rainy season. X Eliminate discharge of contaminants during MS4
maintenance X
Implement controls to limit infiltration of seepage from sanitary sewers to the storm drains X
Implement routine preventative maintenance for both
systems, survey sanitary sewer and MS4. May use SSO
General Waste Discharge Requirement [WDR] to fulfill
this requirement.

X
Implement inspection and maintenance program for
Permittee owned BMPs X
Manage residual water in treatment control BMPs
removed during maintenance X
Street sweeping - Priority A: 2x/mo; B: 1x/mo; C: as
needed, not less than 1x/yr X X Implemented X Implemented X Implemented X Implemented Implement road construction maintenance BMPs (e.g.,
restrict paving activity to exclude periods of rain) X
Inspect and/or clean Permittee owned parking lots
2x/mo X X Implemented
Train employees and contractors on stormwater
requirements X X Implemented
Train employees and contractors on pesticide use X
D.10 Illicit Connections and Illicit Discharges Elimination Continue IC/ID program X X Implemented X Implemented X Implemented X Implemented Written procedures for conducting investigations and
eliminations X X Milestone: 1/1/2016
Initiate investigation within 72 hours from becoming
aware of the discharge X X Implemented
Implement solutions to eliminate discharge; conduct
follow-up investigation to verify elimination; follow
Progressive Enforcement Plan (see Part VI.D.2)
X X Implemented X Implemented X Implemented X Implemented When discharge originates upstream of jurisdiction,
notify the upstream jurisdiction and LARWQCB within 30
days
X
Initiate investigation within 21 days for illicit connection X Permit or document illicit connection that only discharge stormwater or allowed non-stormwater
X
Eliminate illicit connection within 180 days of
investigation X
Facilitate public reporting via hotline X X Implemented

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2012 Permit Requirement
Baseline
Requirement
Maintained by
all Cities
General Beach
Cities MCM
Enhancement
(all Cities)
City-Specific MCM Enhancement
City of Manhattan Beach City of
Redondo Beach
City of
Hermosa Beach City of Torrance
MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented? MCM Milestone/ Already
Implemented?
Signage adjacent to open channels provide info re: public reporting X
Document calls and actions associated with hotline X X Implemented Implement procedures on responding to complaints;
evaluate and update procedures
X X Implemented
Implement a spill response plan X X Implemented
Train staff and contractors on ID/IC X X Implemented
Create a list of positions and contractors that require ID/IC training X

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2.6.3 QUANTIFIED NON-STRUCTURAL BMPS
Non-structural BMPs have been categorized as follows for purposes of RAA. Specific model inputs are summarized in tabular format below.

Non-Modeled Programmatic BMPs
These source controls include a combination of BMPs such as new or enhanced pet waste controls (ordinance, signage, education/outreach, mutt mitts, etc.), Clean Bay Restaurant Program, human waste source tracking and remediation (e.g., leaking sewer investigations including implementation of each agency’s Sanitary Sewer Management Plan consistent with Statewide WDRs, etc.), enhanced street sweeping (e.g., 100% vacuum sweepers, increased frequency, posting of ‘No Parking’ signs for street sweeping, etc.), increased catch basin and storm drain cleaning, and other new or enhanced nonstructural BMPs that target the pollutants addressed in this EWMP. A combined credit of 2.5 – 7.5% load reduction (average of 5%) was applied for all pollutants to represent the cumulative benefit from these BMPs.

Modeled Redevelopment
Beginning in 2001, redevelopment projects were required by the Permit (via the Standard Urban Stormwater Management Program [SUSMP]) to incorporate stormwater treatment BMPs into their projects if their project size exceeded specified thresholds. The 2001 MS4 Permit SUSMP redevelopment requirements were applied between 2003 (the point at which the Bacteria TMDL was implemented) and 2015 for the SMB EWMP area. Redevelopment in this period was modeled as flow-through media filters at a 0.2 in/hr design event.

The 2012 MS4 Permit established new criteria for redevelopment projects, requiring certain sized projects to capture, retain, or infiltrate the 85th percentile design storm or the 0.75-inch design storm, whichever is greater, via the implementation of LID BMPs. To account for these redevelopment requirements, BMPs were modeled in SBPAT assuming land use-specific annual redevelopment rates for projects that triggered former SUSMP requirements or will trigger the Permit’s LID BMP requirements (Table 2-9).

Table 2-9. Estimated Annual Redevelopment Rates
Land Use
Annual Redevelopment Rate (% of total land use area)
Cities of Redondo Beach and
Torrance1
City of Hermosa
Beach
City of Manhattan
Beach
Residential 0.18 0.31 0.10
Commercial 0.15 0.79 0.38
Industrial 0.34 0.79 0.38
Education 0.16 0.16 0.16
Transportation 2.7 2.7 2.7
1 Regionally developed redevelopment rates were applied to the City of Torrance and Redondo Beach (City of Los Angeles Bureau of Sanitation, 2012).

Redondo Beach and Torrance areas used regionally developed redevelopment rates. For Hermosa Beach, the recent 4-year rate for redevelopment of residential areas was used based on city-specific

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LID implementation tracking data. The rate of redevelopment in all commercial land use categories tracked by SUSMP was combined to give an overall rate for both commercial and industrial (as that City has very few light industrial parcels), for historical as well as future redevelopment.

For Manhattan Beach, a City-specific redevelopment rate of 3.8 percent for commercial redevelopment was provided based on historical SUSMP data over the past ten years. This value was also assumed for historical industrial redevelopment as well as future commercial and limited industrial redevelopment. For the residential land use, because there are insufficient data to project LID rates, a nominal 0.10 percent was assumed.

BMPs were assumed to be implemented and to continue to be implemented in the future, at these rates across two distinct time periods:
• 2003 (SMBBB TMDL Effective Date) - 2015: The SUSMP requirements, based on the 2001 MS4 Permit, were assumed to be implemented over this period as flow-through media filters at a 0.2 in/hr design intensity (Los Angeles County Department of Public Works, 2002). • 2015 – 2021 (SMBBB TMDL Final Compliance Deadline): The 2012 MS4 Permit postconstruction requirements were assumed to be implemented over this period as 50% biofiltration and 50% bioretention. Biofiltration (bioretention with underdrains) were modeled using bioswale BMP types with effluent EMCs set to bioretention and sized to retain 150 percent of the 1-year, 1-hour design storm (approximately 0.3 in/hr)16 because they do not retain all the design storm volume on site (they are flow-through systems), while bioretention units were sized to retain 100 percent of the 85th percentile, 24-hour design storm depth, calculated as the mean for each analysis region.
2015 is used as a transition date since the LID post-construction requirements from the 2012 MS4 Permit are required to be in full effect via local LID ordinances by this time.

In order to estimate load reductions associated with these redevelopment BMPs, the land use percentages shown in Table 2-1 were multiplied by the respective land use areas in each analysis region, resulting in an assumed area treated by LID BMPs each year. This area was multiplied by the applicable number of years, since new BMPs are assumed to be implemented each year. The total land use area assumed to be redeveloped for each analysis region was then modeled as being treated by the BMPs described below (Table 2-10) and the total load reduction was quantified.

The default design parameter assumptions for the biofiltration redevelopment projects were that the longitudinal slopes were 0.03 ft/ft, Manning’s n was 0.25, hydraulic residence time was 10 min, and water quality flow depth was 4 inches.

16 150% of the 1-year, 1-hour design storm was used per Section VI.D.7.c.iii of the Permit.

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Modeled Public Retrofit Incentives
These BMPs include programs directed at incentivizing the public to decrease the amount of stormwater runoff from their property, specifically via downspout disconnects. Public incentives for retrofitting existing development were modeled in SBPAT between 2015, when the EWMP will begin to be implemented, and the respective TMDL final compliance date. Public retrofit incentives were assumed to be a downspout disconnection program, modeled as bioswales sized to a design storm intensity of 0.2 in/hr (Table 2-10). The default design parameter assumptions for the biofiltration redevelopment projects were that longitudinal slopes were 0.03 ft/ft, Manning’s n was

0.25, hydraulic residence time was 10 min, and water quality flow depth was 4 in.

It was assumed that 10 percent of single family residential areas would be converted to disconnected downspout systems over 2015 to 2021, and that, based on GIS analysis, 38 percent of the single family residential area consists of rooftops that can be effectively disconnected.

Therefore, 3.8 percent of single family residential neighborhoods were modeled as treated by bioswales in order to account for public retrofit incentives.

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Table 2-10. Redevelopment and Public Retrofit Incentives Model Assumptions Implementation
Level BMP Type Design Storm
Longitudinal
Slope
(ft/ft)
Manning
n
Hydraulic
Residence Time
(min)
Water Quality
Flow Depth
(in)
Effective
Retention
Depth (in)
Infiltration
Rate (in/hr)
Redevelopment
(2003-2015) Media Filter 0.2 in/hr - - - - - -
Redevelopment
(2015-2021)
Biofilters1 0.3 in/hr 0.03 0.25 10 4 2
Based on
analysis regionspecific soil type
Bioretention 0.75 in - - - - 12 0.15
Public Retrofit
Incentives
(2015-2021)
Bioswales
representing
downspout
disconnects

0.2 in/hr 0.03 0.25 10 4 2
Based on
analysis regionspecific soil type
1 Modeled as bioswales using bioretention effluent EMCs

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Modeled Non-MS4 Permitted Parcels or Areas
SBPAT was used to quantify the load reduction assuming that regulated parcels/areas would be in compliance with the NPDES Statewide Storm Water Permit Waste Discharge Requirements (WDRs) from State of California Department of Transportation (Order No. 2012-0011-DWQ, NPDES No.

CAS000003) and the California NPDES General Permit for Storm Water Discharges Associated with Industrial Activities (Industrial General Permit [IGP], Order 2014-0057-DWQ) (Figure 2-12).

A load reduction was obtained from these areas by simulating treatment plants sized to treat the IGP’s design storm requirement, the 85th percentile, 24-hour storm event (0.2 in/hr), with an effluent concentration set equal to the water quality standard (Table 2-11). For fecal coliform, 400 MPN/100mL was used.

Table 2-11. Non-MS4 Parcels – Modeled as Treated by Treatment Plants (i.e., BMPs that will treat stormwater to the Water Quality Objectives)
Implementation Level BMP Type
Treatment
Flowrate
(cfs)
Design
Storm
(in/hr)
Average
Basin
Depth
(ft)
Equalization
Volume
(cu-ft)
Diversion
Flowrate
(cfs)
Infiltration
Rate
(in/hr)
Non-MS4
Parcels
Treatment
Plant 10,000 0.20 100.00 1,000 10,000 0.00001

2.6.4 STRUCTURAL BMPS
Existing (constructed between 2003 and 2014) and proposed structural BMPs (regional and distributed) were modeled in SBPAT based on best available design information. The following sections outline the structural BMPs that were modeled as well as their drainage areas, design details in SBPAT, and any relevant assumptions. Modeled regional BMPs are depicted in Figure 2-13. Modeled distributed BMPs are depicted in Figure 2-14.

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Figure 2-12. IGP and Caltrans Area within the Santa Monica Bay portion of the Beach Cities EWMP Area

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Figure 2-13. Existing and Proposed Regional BMPs within EWMP Area

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Figure 2-14. Existing and Proposed Distributed BMP Locations within the EWMP Area

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Existing Regional BMPs
Analysis Regions SMB-5-02 and SMB-5-03/SMB-5-04
The Manhattan Beach Green Belt Infiltration Project tributary area spans analysis regions SMB-5-02 and SMB-5-03/SMB-5-04. The Project, completed in February 2013, utilizes the linear greenbelt parkland that runs through the City to intercept and infiltrate dry weather and wet weather low flows from existing storm drains that intersect the parkway. The Project was designed to reduce the downstream peak flow and runoff volume from the 55.2 acres of contributing developed residential land use while also increasing groundwater recharge and subsequently increasing the effective permeability of the developed area. The 55.2 acre drainage area is part of the 161 acre tributary area that drains to the 1st Street outfall and Santa Monica Bay , which is part of the approximately 205 acres of drainage influencing the SMB-5-04 open beach monitoring site under the CSMP (2004).

Analysis Region SMB-5-05
The Pier Avenue Improvement Project captures and treats stormwater/urban runoff from residential areas on
surrounding streets and commercial development in the
downtown corridor along Pier Avenue (36-acre drainage
area). The Project includes drainage improvements for
treatment and infiltration of dry and wet-weather flows up to the design storm to reduce pollutant loading at the beach and to reduce flooding.

The Hermosa Strand Infiltration Trench project receives runoff from a 76.2-acre, intensely developed mixed
commercial and residential coastal subdrainage area conveyed via the Pier Avenue storm drain.

The Pier Avenue storm drain was retrofit with a diversion structure and tide gate to direct dryweather flows and wet weather low flows from the storm drain into a pump well, through a bafflebox pretreatment unit, then into the subsurface infiltration trench 1,000 feet long constructed on the beach adjacent to the Strand. The diversion pump was designed to divert up to 250 gallons per minute (GPM), which is significantly greater than would be required solely to divert dry weather runoff from the drainage area, thereby allowing for diversion of some wet weather flows.

Analysis Region SMB-6-01
Three existing regional BMPs were modeled within analysis region SMB-6-01. These include Amie Basin, Entradero Basin, and Henrietta Basin in their post-enhancement state. Since the basins were in existence prior to the 2003 TMDL effective date, pollutant removal credit was not assigned to the basins for their pre-2003 function, rather only the basin improvement design parameters that 1) improved water quality and 2) were implemented post-2003 were modeled. Infiltration rate, depth, volume, and discharge rate of the basins and their extended storage were extracted from

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analysis of the stage-discharge curves provided in the Stormwater Basin Enhancement Project Design Memorandum (CWE Corp., 2012).

Amie Basin, post-enhancements. Amie Detention Basin is an existing BMP that captures runoff from 409 acres of upstream land in analysis region BCSump, which drains to SMB-6-01. Based on boring test results, the average on-site infiltration rate is reported as 0.0082 in/hr. Due to its limited infiltration capacity, Amie Detention Basin is not designed for the purpose of on-site infiltration. Instead, its primary purpose is to discharge runoff slowly to the downstream Henrietta Detention Basin. The basin enhancements, completed in August 2015 (City of Torrance, 2014), increased the extended retention volume by reducing the permanent pool volume by 25% by creating additional flow paths within the basin. Due to the nature of the basin enhancements, Amie Detention Basin was modeled as a wet pond with extended detention capacity.

Entradero Basin, post-enhancements. Entradero
Detention Basin is an existing BMP that treats
runoff from 436 acres of upstream land in analysis
region SMB-6-01 and is sized to capture the 0.75
inch storm. Based on boring test results, the
average on-site infiltration rate is 1.28 in/hr. To
increase the infiltration capacity, the postenhancement design project, which was completed in August 2015 (City of Torrance, 2014),
significantly increased the infiltration surface area
from 0.03 acres to 1.44 acres. Entradero Detention
Basin was modeled as an infiltration basin. The basin includes a small permanent pool (1500 cubic feet), the volume of which was excluded from the calculation of total storage capacity.

Henrietta Basin, post-enhancements. Henrietta
Detention Basin is an existing BMP that treats
runoff from Amie Detention Basin as well as an
additional 153 acres of upstream land in analysis
region BCSump for up to 0.75 inches storm. Based
on boring test results, the average on-site
infiltration rate is 2.1 in/hr. To further increase
the infiltration capacity, recent design
enhancements (completed in August 2015 (City of
Torrance, 2014)) increased the maximum basin
depth from 23 feet to 30 feet, and created additional flow path within the basin. In SBPAT, the Henrietta basin is modeled as an infiltration basin. The basin included a small permanent pool (6900 cubic feet), the volume of which was excluded from the total storage capacity.

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Analysis Region SMB-6-02
The Alta Vista Park Diversion and Re-Use Project is
located in Redondo Beach and is designed to divert
wet weather flows up to a rainfall event of 0.3 inches
in 24 hours, collected from its 101-acre watershed.

HDPE pipes comprise the approximately 100,000
gallons of underground storage. Excess overflows
from the tank go into a 4,200 square feet infiltration
bed located under the tank. The Project diversion
facilities include structures that divert up to 4.5 cfs of the storm flow through a gross pollutant removal
device.

Analysis Region SMB-6-03
The Sapphire Street Infiltration BMP consists of a low flow diversion and infiltration bed. The low flow diversion is intended to divert all dry weather flow and wet weather runoff from a storm up to

0.1 inches in 24 hours. The diversion facilities include a structure that will divert up to 11 cfs of the storm flow through a CDS unit. A smaller amount, up to 160 gpm, are diverted to a pump station that pumps the water to two stormwater bioretention filtration units, where it is then conveyed to the infiltration bed.

Summary of Existing Regional BMPs
The existing regional BMPs, including their location, analysis region, model inputs, and expected performance, are summarized in Table 2-12 and Table 2-13. Wylie Sump and its tributary area were excluded from the RAA analysis because it is an 85th percentile capture project and also does not produce outflow and would therefore have no impact on the TLR or contribute any loads. The Wylie Sump receives runoff from 38 acres of the City of Manhattan Beach, 20 acres of Hermosa Beach, and 73 acres of Redondo Beach. There are no other 85th percentile capture projects in the Santa Monica Bay Watershed portion of the Beach Cities EWMP Area.

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Table 2-12. Parameters and Performance for Existing Regional BMPs Modeled as Infiltration Basins Location
of BMP
Analysis
Region Project Name
Model Inputs Expected
Performance (load
reduction as a % of
analysis region
baseline load)
Design
Storage
Volume
(cu-ft)
Design
Storm
(in)
Average
Depth
(ft)
Diversion Rate
(cfs)
Infiltration
Rate
(in/hr)
Manhattan
Beach
SMB-5-03/
SMB-5-04 Manhattan Beach
Green Belt Infiltration - 0.45 2.6 6.7 2.1

4.7%
SMB5-02 1.1%
Hermosa
Beach SMB-5-05
Pier Avenue
Improvement Project
infiltration systems
- 0.21 2.6 11 0.77 2.3%
Hermosa
Beach
SMB-5-03/
SMB-5-04
Hermosa Strand
Infiltration Trench 1,400 - - 2.9 0.56

0.5%
SMB-5-04/
SMB-5-05 1.9%
SMB-5-05/
SMB-6-01 2.0%
SMB5-04 1.4%
SMB5-05 0.9%
SMB6-01 0.2%
Torrance SMB-6-01
Entradero Detention
Basin Enhancement 88,860 - 2.0 16 1.3 2.6%
Henrietta Detention
Basin Enhancement 383,000 - 12.0 54 2.1 4.6%
Redondo
Beach SMB-6-02
Alta Vista Park
Diversion and Re-Use
Project
- 0.30 3.0 4.5 0.18 3.8%
Redondo
Beach SMB-6-03 Sapphire St Infiltration BMP - 0.10 1.5 11 0.74 9.5%

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Table 2-13. Parameters and Performance for Existing Regional BMPs Modeled as Wet Ponds with Extended Detention Location
of BMP
Analysis
Region Project Name
Model Assumptions Expected
Performance (load
reduction as a % of
analysis region
baseline load)
Volume
(cu-ft)
Surcharge
Depth
(ft)
Surcharge
Drawdown
Time
(hr)
Permanent
Pool
Volume
(cu-ft)
Permanent
Pool Depth
(ft)
Diversion
Flowrate
(cfs)
Torrance SMB-6-01
Amie
Detention
Basin Post
Enhancement
5,600,000 45 160 99,750 5 46 8.8%

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Proposed Regional BMPs
Analysis Region SMB-5-02 Regional BMP Parameters and Criteria One regional BMP (Alternative 1) is being proposed and was modeled within analysis region SMB-5-02 (Figure 2-15) — Manhattan Beach Infiltration Trench Project (see Table 2-13).

The Manhattan Beach Infiltration Trench site is proposed along a public beach adjacent to a walking/bike path and consists of recreational open space. The project has an approximate infiltration footprint of 2.2 acres and drainage area of 1,600 acres. The storage volume of the project was estimated as 4.6 acre-feet, with an estimated drawdown time of 72 hours.

Additional benefits achieved by this project include infiltration to help prevent intrusion of shallow saline groundwater associated with sea level rise in order to protect subsurface infrastructure from corrosion, as well as potential dune habitat restoration. This BMP can also increase public awareness through educational signage.

An alternative design (Alternative 2) is for a beach infiltration trench at 80% of Alternative 1 in combination with an
infiltration-based BMP at Polliwog Park, which would
achieve approximately 10% of the target load reduction needed for analysis region SMB-5-02 and could potentially offset 20% of the required storage capacity of the Manhattan Beach Infiltration Project (Figure 2-15). In other words, the load reduction of Polliwog Park infiltration is equivalent to that of Manhattan Beach Infiltration Trench at 20% of its full Alternative 1 treatment volume. The addition of the Polliwog Park BMP would result in the additional benefits of neighborhood greening, mitigating issues such as the urban heat island effect, and also raising public education/awareness.

The construction of a wetland would provide the additional benefit of expanding riparian habitat, and also help mitigate downstream flood control issues.

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Figure 2-15. Proposed Regional Projects, Analysis Region SMB-5-02

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Analysis Region SMB-6-01 Regional BMP Parameters and Criteria Three regional BMPs (and one potential alternative) are proposed within Analysis Region SMB-6-01, as described below, and depicted in Figure 2-16.

Park #3. The Park #3 Project was identified as a potentially suitable site for several different BMP types, including infiltration, wetlands, or a detention basin. Park #3 is located northwest of Blossom Ln. and 190th St, and has an approximately footprint of 0.4 acres and drainage area of 1,430 acres. The storage volume of the project was estimated as 87,100 cubic feet. Diversion flowrate was assumed to be 0.015% of the volume for preliminary planning purposes. This BMP would provide the additional benefits of neighborhood greening, mitigating issues such as the urban heat island effect and also raising public education/awareness. The construction of a wetland would provide the additional benefit of expanding riparian habitat, and also help mitigate downstream flood control issues.

Hermosa Beach Greenbelt Project. The Greenbelt site in Hermosa Beach was identified as a potentially suitable site for several different BMP types, including infiltration, wetlands, or a detention basin. The Greenbelt is situated between Valley Dr. and Ardmore Ave. and has a potential footprint of 1.5 ac and an approximate tributary area of 1,800 acres. The project storage volume is a function of its footprint.

The diversion flowrate was assumed to be 0.015% of the volume for preliminary planning purposes.

Powerline Easement. A potential alternative location to the Hermosa Beach Greenbelt Project facility is located south of Herondo Street between N. Francisca Ave. and N. Catalina Ave., within a powerline easement.17 Both potential locations for the greenbelt project would provide the additional benefits of neighborhood greening, mitigating issues such as the urban heat island effect and also raising public education/awareness.

The construction of a wetland would provide the additional benefit of expanding riparian habitat, and also help mitigate downstream flood control issues.

17 If this proposed design is to be developed within the powerline easements, certain considerations should be made. To alleviate concerns of saturating soils around powerline footings, and to allow for powerline maintenance activities to occur, stormwater facilities should be installed at least 100 feet from any tower and 10 feet from any pole. Special consideration and increased distances may be necessary when working around “dead-end” towers, or towers where transmission lines change direction. Access road clearance should also be maintained and basin depth must be considered for safety and illegal dumping purposes.

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Hermosa Beach Infiltration Trench. The Hermosa Beach
Infiltration Trench project has a tributary area of 2000 acres. The project may be designed to reduce downstream water volumes and facilitate compliance with the dry-and wet-weather WLAs allotted in the SMBBB TMDL at the SMB-6-01 CML. If upstream projects (e.g., LID projects) and other City activities are implemented, TMDL compliance may be able to be achieved under reduced design requirements. Additional benefits achieved by this project include infiltration to help prevent intrusion of shallow saline groundwater associated with sea level rise in order to protect subsurface infrastructure from corrosion, as well as potential dune habitat restoration. This BMP can also increase public awareness through educational signage.

Figure 2-16. Proposed Regional Projects, Analysis Region SMB-6-01 Summary of Proposed Regional BMPs
Four regional BMPs are proposed in the Santa Monica Bay Watershed portion of the Beach Cities EWMP Area. None of these projects could be feasibly sized to meet the 85th percentile design criteria.

However, the BMPs were sized to collectively meet the target load reductions necessary to achieve compliance with the WQBELs and RWLs, in combination with other existing and proposed structural and non-structural BMPs. Proposed regional BMPs, including their location, analysis region, project name, model inputs, and expected performance, are summarized in Table 2-14.

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Table 2-14. Parameters and Performance for Proposed Regional BMPs Modeled as Infiltration Basins Analysis
Region Location of BMP Project Name
Model Assumptions
Expected Performance
(load reduction as a % of
analysis region baseline
load)
Design
Storage
Volume
(cu-ft)
Design
Storm
(in)
Average
Depth
(ft)
Diversion
Rate
(cfs)
Infiltration
Rate
(in/hr)
SMB-5-02 Manhattan Beach
Manhattan Beach
Infiltration Trench, Alt 1 198,000 - 2.1 160 13 36.5%
Manhattan Beach
Infiltration Trench, Alt 2 158,400* - 2.1 160 13 32.1%1 Polliwog Park
Infiltration, Alt 2 148,000 - 4.0 11 0.7 4.4%
SMB-6-01
Hermosa Beach
Hermosa Beach
Greenbelt Infiltration 319,000 - 5.0 48 12 15.1%
Hermosa Beach
Infiltration Trench 13,300 - 1.70 25 13 0.4%
Redondo Beach Park #3 BMP Project 87,100 - 5.00 410 1.0 1.3% 1 The treatment volume of Manhattan Beach Infiltration Trench in Alternative 2 is set at 80% of the Alternative 1 volume so that load reductions achieved by BMP configurations in Alternative 1 and Alternative 2 are identical.

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Existing Distributed BMPs
In 2008-09, the City of Hermosa Beach retrofitted the east side of Hermosa Avenue between 27th and 35th Streets with a series of seven filter/infiltration boxes to intercept, filter, and infiltrate low flows conveyed down side streets from the areas east of Hermosa Avenue prior to entry into catch basin inlets on Hermosa Avenue. The infiltration boxes were modeled in the RAA analysis as two bioretention systems due to their infiltration capabilities and combined into two systems (System A and System B) — one system per analysis region SMB-5-04 and SMB-5-03/SMB-5-04, respectively. The City of Manhattan Beach also replaced several downtown asphalt parking lots with pervious concrete. See Table 2-15 and Figure 2-14 for design assumptions and BMP locations.

Proposed Distributed BMPs
Proposed distributed BMPs, including green streets, were modeled by assuming that stormwater runoff from high priority land use areas can be treated in the right-of-way, and 50%-50% use of biofilters and bioretention. Biofilters (also known as bioretention with underdrains) were sized to 150% of the 85th percentile, 24-hour design storm (0.3 in/hr) because they do not retain on site (they are flow-through systems), while bioretention units were sized to 100% of the 85th percentile, 24-hour design storm depth, calculated as the mean for each analysis region. Biofilters were modeled using bioswale volume reduction and bioretention effluent EMCs. Default modeling assumptions included longitudinal slopes of 0.03 ft/ft, Manning’s n of 0.25, hydraulic residence time of 10 min, and water quality flow depth of 4 in.

Distributed green streets were implemented at similar rates (as a percentage of land use area) in residential and commercial land uses. Distributed BMPs were applied at levels unique to each analysis region, iteratively determined based on compliance with TLRs, after accounting for load reductions attributable to nonstructural and regional BMPs. They were applied by assuming treatment of stormwater from analysis region-specified percentages of single family, multi-family, and commercial land use areas, until TLRs are met. These land use and BMP type combinations were chosen based on their ability to result in maximum bacteria load reduction.

In order to minimize redundancy of BMP coverage and avoid double-counting BMP benefits, distributed BMPs were not applied in the drainage area footprints of existing regional BMPs.

However, they were modeled in the drainage area of proposed BMPs, as long as both were included in the same model run to avoid double counting. Performance of existing and proposed distributed BMPs are shown in Table 2-16.

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Table 2-15. Existing and Proposed Distributed BMPs
Implementation
Level
Analysis
Region(s) BMP Type
Design
Storm
Longitudinal
Slope
(ft/ft)
Manning
n
Hydraulic
Residence
Time
(min)
Water Quality
Flow Depth
(in)
Effective
Retention
Depth (in)
Infiltration
Rate (in/hr)
Existing
Manhattan Beach
Porous Paving
Project – El Porto
Lot
SMB-5-01 Porous
Pavement Removal of existing asphalt and replacement with 10 inches of porous concrete Existing
Distributed Green
Streets BMPs
(2003-2015)1
SMB-5-04
(System A) Bioretention 0.038 - - - - 35 10
SMB-5-
03/SMB-5-04
(System B)
Bioretention 0.026 - - - - 35 10
Proposed
Distributed Green
Street BMPs
(2015-2021)
MFR and
COM/SFR land
uses in
BCSump, SMB5-02, and SMB6-01
Biofilters2 0.3 in/hr 0.03 0.25 10 4 2
Based on
analysis regionspecific soil
type
Bioretention
Varies by
analysis
region (0.77
to 0.82 in)
- - - - 12 0.15
1 In 2008-09 the City of Hermosa Beach retrofit the east side of Hermosa Avenue with a series of seven (7) filter/infiltration boxes to intercept, filter, and infiltrate low flows conveyed down side streets from the areas east of Hermosa Avenue prior to entry into catch basin inlets on Hermosa Avenue. The infiltration boxes were modeled as two bioretention systems due to their infiltration capabilities and combined into two systems (System A and System B) — one system per defined subcatchment. 2Modeled as a bioswale using bioretention EMCs.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-68 | Page 201 8
Table 2-16. Existing and Proposed Distributed BMP Performance Analysis Region Implementation Level Status
Estimated load reduction
(as % of analysis region
baseline load)
SMB-5-04 N/A - Existing Existing 1%
SMB-5-03/
SMB-5-04 N/A - Existing Existing 0.1%
SMB-5-02 5% on MFR/COM/SFR land
uses Proposed 3%
SMB-6-01+BCSump1 25% on MFR/COM/SFR land
uses Proposed 2%
1 “BCSump” was defined as a separate analysis region for modeling purposes. The baseline load for “BCSump” analysis region was combined with the baseline load of the “SMB-6-01” analysis region to equal the total baseline load contributing to the SMB-6-01 CML (“SMB-6-01+BCSump”).

2.7 REASONABLE ASSURANCE ANALYSIS RESULTS

2.7.1 WET WEATHER
Quantitative analyses were conducted for each analysis region separately and are summarized below. Average BMP load reduction results for each analysis region are presented in Table 2-17 below. Detailed results for all BMPs in terms of volume, concentration, and load for each WBPC and analysis region can be found in the electronic data files submitted along with the Beach Cities EWMP. An example illustrating the modeling results of applicable pollutant concentrations at the downstream outlet of the watershed system is included in Appendix K. The values provided correspond to the fecal coliform load reductions attributable to the BMP types at both the interim (2018) and final (2021) TMDL compliance deadlines. As shown, the TLRs were met in all analysis regions as a result of varying levels of implementation of non-structural and regional BMPs as described previously. The interim 50% TLR is met through a combination of nonstructural and existing regional BMPs. It should be noted that if at any time specific distributed green streets or regional/centralized BMPs are found to be infeasible for implementation, alternative BMPs or operational changes will be planned within the same subwatershed and within the same timeline, to meet an equivalent subwatershed load reduction, unless the TLRs or compliance schedules are modified.

Because USEPA’s Santa Monica Bay DDT and PCBs TMDL effectively implements an antidegradation approach to set MS4 WLAs to maintain and protect the receiving waters and meet water quality standards, the existing MS4 PCB and DDT loads from the Beach Cities EWMP Area are reasonably assumed to be in compliance with the applicable WLAs. Therefore, a target load reduction of zero has been set for PCBs and DDT. In spite of the zero required load reduction for PCBs and DDT in Santa Monica Bay for the Beach Cities EWMP Group, the BMPs proposed in this EWMP are expected to reduce sediment and sediment-associated pollutants such as DDTs and PCBs, so the non-quantified but greater-than-zero anticipated BMP load reductions for DDTs and PCBs will exceed the TMDL WLA. Therefore, compliance with the TMDL-based permit limits for DDTs and PCBs has been demonstrated through this narrative RAA evaluation.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-69 | Page 201 8
Table 2-17. Santa Monica Bay Watershed – Fecal Coliform RAA Results – Interim and Final Compliance Analysis
Region
Implementation Benefits (average load reduction as % of baseline load for critical year) TLR
Compliance
(TLR Met)?
NonStructural
BMPs (NonModeled)
Public Retrofit
Incentives +
Redevelopment
NonMS4Regional
BMPs
Distributed
BMPs
Distributed
BMP
Implementation
Level
Estimated
Load
Reduction
SMB-5-01 5% 2% 0% 0% 0% N/A 7% 0% Yes
SMB-O-06 5% 2% 0% 0% 0% N/A 7% 0% Yes
SMB-5-02 5% 4% 2% 36% 3% 5%
MFR/COM/SFR 50% 46% Yes
SMB-5-02/5-03 5% 3% 0% 0% 0% N/A 8% 0% Yes
SMB-5-03 5% 3% 0% 0% 0% N/A 8% 0% Yes
SMB-5-03/5-04 5% 4% 0% 5% 0% N/A 15% 0% Yes
SMB-5-04 5% 5% 0% 1% 1%2 N/A 12% 0% Yes
SMB-5-04/5-05 5% 4% 0% 2% 0% N/A 11% 0% Yes
SMB-5-05 5% 4% 5% 3% 0% N/A 18% 0% Yes
SMB-5-05/6-01 5% 3% 0% 2% 0% N/A 10% 0% Yes
SMB-6-01+
BCSump1 5% 3% 3% 33% 2% 25% MFR/COM/SFR 46% 45% Yes
SMB-6-01/6-02 5% 2% 4% 0% 0% N/A 11% 0% Yes
SMB-6-02 5% 3% 1% 4% 0% N/A 13% 0% Yes
SMB-6-03 5% 3% 5% 10% 0% N/A 23% 0% Yes
SMB-6-04 5% 4% 3% 0% 0% N/A 12% 0% Yes
SMB-6-05 5% 3% 6% 0% 0% N/A 15% 0% Yes
SMB-O-08 5% 2% 0% 0% 0% N/A 7% 0% Yes
SMB-6-06 5% 5% 0% 0% 0% N/A 10% 0% Yes
Final Compliance
Deadline (2021) 5% 3% 3% 21% 1% N/A 33% 26% Yes
Interim
Compliance
Deadline (2018)3

2.5% 0.8% 1.5% 9.6% 0% N/A 14.4% 13% Yes
1 “BCSump” was defined as a separate analysis region for modeling purposes. The baseline load for “BCSump” analysis region was combined with the baseline load of the “SMB-6-01” analysis region to equal the total baseline load contributing to the SMB-6-01 CML (“SMB-6-01+BCSump”). 2 Distributed green street BMP load reduction in SMB-5-04 is a result of the existing filter/infiltration boxes retrofitted on the east side of Hermosa Avenue in the City of Hermosa Beach. 3 The total interim load reduction is the sum of the load reductions calculated for each analysis region by 2018. The TLR is met through a combination of nonstructural and existing regional BMPs.

Beach Cities EWMP | Section 2 | Santa Monica Bay Watershed 2-70 | Page 2018
Time Series Output
Electronic input and output SWMM files and Excel summary spreadsheets will be provided to the LARWQCB upon submittal of this Draft EWMP
Consistency with LARWQCB Guidance
The approaches described above, including model selection, data inputs, critical condition selection (90th percentile year), calibration performance criteria, and output types were selected for consistency with the LARWQCB RAA Guidance Document (LARWQCB, 2014).

2.7.2 DRY WEATHER
For dry weather bacteria compliance, a qualitative analysis was conducted to show compliance at each of the CMLs. Table 2-18 outlines the results of this analysis. Many CMLs have an effective diversion18 such that they are consistently operational, well maintained, and sized to effectively eliminate discharges to the surf zone during year-round dry weather days. For the remaining smaller outfalls a systematic screening conducted in 2002 demonstrated that there was no discharge to the wave wash during summer dry weather from these storm drains. Rescreening of outfalls will be conducted as part of the Non-Stormwater Screening and Monitoring in the Coordinated Integrated Monitoring Program and will include both summer dry weather and winter dry weather screening. For the CMLs in the SMB Watershed that have anti-degradation based allowed exceedance days for both winter-dry and summer-dry weather, reasonable assurance is assumed to be demonstrated through the basis that the TMDL established their allowed exceedance days based on historic conditions (i.e., no water quality improvements were necessary).

If following dry weather outfall re-screening, dry weather reasonable assurance has not been demonstrated by the evaluation criteria shown in Table 2-18, the Beach Cities EWMP Group’s compliance approach is consistent with the Permit requirement to eliminate 100 percent of nonexempt dry weather MS4 discharges. The Group’s implementation approach for achieving this is to use a suite of non-structural source controls (e.g., water conservation incentives, enhanced illicit discharge detection and elimination [IDDE] efforts, and enhanced education/outreach and inspection/enforcement to prevent non-exempt sources of stormwater flow) and source investigations. By eliminating flows, this is equivalent to 100 percent load reduction for all pollutants, thereby demonstrating reasonable assurance of meeting all applicable TMDL limits and water quality objectives in the Permit during dry weather. Elimination of discharges is a pathway for compliance with RWLs and WQBELs in the MS4 Permit (per Section VI.E.2.e.i.(3)); without discharges there can be no “cause or contribute” to receiving water issues.

Since the dry weather compliance deadlines for the SMBBB TMDL have passed, this analysis is provided for informational purposes only, and is not intended to support or justify a new

18 The seven existing low flow diversions include Polliwog Park, SMB 5-2 (28th Street), SMB 5-3 (Manhattan Beach Boulevard), SMB 5-5 (south of Pier Avenue), SMB 6-1 (Herondo Street), SMB 6-3 (Sapphire Street), and SMB 6-5 (Avenue I).