Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs DRAFT

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs EWMP Final Work Plan 5.A 1 XX 2015 Appendix 5.A: Comparison of 2001 Permit MCMs to 2012 Permit MCMs MCM 2012 Permit Requirement 2001 Permit Requirement D.2 Progressive Enforcement (Applies D.6, D.7, D.8, and D.10) Develop and maintain a Progressive Enforcement Policy Conduct follow up inspection within 4 weeks of date of initial inspection Take progressive enforcement Retain records Refer violations to Regional Board Investigate complaints from Regional Board (RB) Assist RB with Enforcement Actions 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 Implement public information and participation program Media campaign for Storm Water Pollution Prevention (SPP) Strategy to educate ethnic communities about SPP Enhance outreach for proper disposal of cigarette butts Conduct educational activities within jurisdiction and participate in county wide events Organize Public Outreach Strategy meetings quarterly Conduct Media Outreach to 35 million impressions per year Coordinate watershed specific pollution prevention outreach programs Corporate Outreach Program to target retail gas outlets and restaurant chains Coordinate an SPP program for a Business Assistance Program Behavioral change assessment strategy towards SPP Maintain reporting hotline Maintain the (888) CLEAN LA hotline Publish hotline info on web, telephone book ID staff/department that serve as the contact (publish this info) Provide a list of reporting contacts to public through www.888cleanla.com Coordinate and provide contact information for public education activities Organize events (e.g., clean ups) Residential Outreach (Individually or with group): Public Service Announcements (Develop) Public education materials on: vehicle fluids; household waste; construction waste; pesticides, fertilizers, and integrated pest management (IPM); green wastes; and animal wastes

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs EWMP Final Work Plan 5.A 2 XX 2015 MCM 2012 Permit Requirement 2001 Permit Requirement Distribute public education materials at points of purchase Maintain stormwater website Provide schools with materials to educate children (K 12); can use state produced materials Distribute SPP information to K 12 schools Strategy to measure effectiveness of in school programs Convene an Advisory Committee Mark all storm drain inlets with a "no dumping" message D.6 Industrial/ Commercial Track Critical Sources maintain inventory (watershed based or lat/long recorded) Maintain a list of industrial/commercial facilities to be inspected Educate notify critical sources of BMP requirements Implement a Business Assistance Program for select sectors or small businesses technical assistance, and distribute materials to specific sectors Inspect Commercial Sources Inspect restaurants twice during Permit cycle Inspect Industrial Sources initial mandatory inspection Inspect/visit industrial/commercial facilities appropriately Secondary mandatory inspection No Exposure evaluate and conduct 2nd inspection at 25% of facilities As needed conduct Progressive Enforcement follow up inspections (see D.2) Initiate progressive enforcement for facilities failing to implement BMP's D.7 Planning and Land Development Implement development planning program that requires SUSMP Develop peak flow control criteria Amend codes and ordinances to give legal effect to SUSMP changes in permit Implement revised Standard Urban Storm Water Mitigation Plan (SUSMP) Submit an Environmentally Sensitive Areas (ESAs) Delineation map to RWQCB Implement SUSMP requirements for industrial/commercial projects >1 acre Update CEQA guidelines to include specific storm water related issues Update General Plan to include specific storm water related issues Train targeted employees in permit requirements for Development Planning Develop and make SUSMP guidelines available to the developer Develop a technical manual for the siting and design of BMPs Update ordinance/design standards to conform with new requirements (LID and Hydromod) Optional: Establish alternative compliance for technical infeasibility, e.g., allow onsite biofiltration or offsite infiltration or gw replenishment or retrofit

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs EWMP Final Work Plan 5.A 3 XX 2015 MCM 2012 Permit Requirement 2001 Permit Requirement Optional if allowing offsite mitigation: Develop a prioritized list of offsite mitigation projects Optional if allowing offsite mitigation: Develop a schedule for completion of offsite projects (must be with 4 yrs of the Certificate of Occupancy of the first project that contributed funds) Optional if allowing offsite mitigation: Notice offsite projects to RB website Optional if allowing offsite mitigation: List of mitigation projects descriptions and estimated pollutant and flow reductions Optional if allowing offsite mitigation: Provide aggregated comparison of alternative compliance to results that would have been expected with onsite retention of the SWQDv Optional: Submit documentation that a previously adopted LID ordinance provides equivalent pollutant loading and flow reduction Plan Review process check LID and BMP sizing, etc., Establish internal agreements with structure for communication and authority for departments overseeing plan approval and project construction Require O&M plan for LID, treatment and hydromod BMPs Implement tracking and enforcement program for LID, treatment and hydromod BMPs Inspect all development sites upon completion and prior to occupancy certificates Verify O&M of BMPs operated by Permittee through inspection Develop maintenance inspection checklist Require private parties that operate BMPs to submit verification of O&M; enforce as needed As needed conduct Progressive Enforcement follow up inspections (see D.2) D.8 Construction Implement a development construction program Require proof of a Waste Discharger ID (WDID) number prior to filing Notice of Intent (NOI) Require proof of an NOI and a copy of SWPPP for a transfer of ownership Track the number of issued building and grading permits Update erosion and sediment control ordinance/procedures to conform with new requirements Sites < 1 acre; inspect based upon water quality threat Establish priority inspection process Site < 1 acre; Require sites with soil disturbing activities to implement minimum BMPs Require construction sites to prepare erosion sediment control plan(escp); review and approve ( 1 acre)

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs EWMP Final Work Plan 5.A 4 XX 2015 MCM 2012 Permit Requirement 2001 Permit Requirement Verify construction sites coverage under the CGP and 401 cert Refer General Construction Activities Stormwater Permit (GCASP) violations to RWQCB Develop/implement ESCP review checklist Require construction sites to adhere to standards and make standards readily available 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) Develop/implement SOPs/inspection checklist Track number of inspections for inventoried sites and verify minimum inspections are completed As needed conduct Progressive Enforcement follow up inspections (see D.2) Train plan review staff and inspectors Train targeted employees in permit requirements for Development Construction Staff must be knowledgeable in QSD/P key objectives, local BMPs standards 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 Implement Development Planning Program at Permittee owned construction projects Implement Development Construction Program at Permittee owned construction projects Develop, if needed, and implement SWPPPs for field facilities Maintain inventory of Permittee owned facilities (including parks and recreation facilities,) Update inventory Develop retrofit opportunity inventory; evaluate and rank "Cooperate with private land owners to encourage site specific retrofitting"; includes pilot projects and outreach Obtain IGP coverage for public facilities where appropriate Develop procedures to assess impact of flood mgt projects on water quality of receiving waters; evaluate to determine if retrofitting is feasible Evaluate existing structural flood control facilities to determine if retrofitting facility to provide additional pollutant removal is feasible Implement source control BMPs at Permittee owned facilities/activities Require city hired contractors to implement source control BMPs Prevent vehicle/equipment washing discharges to the MS4, including fire fighting and emergency response vehicles Ensure new/redeveloped/replaced wash facilities are plumbed to the sanitary sewer or self contained. Equip wash areas with a clarifier, pre treatment device, or be connected to sewer Implement IPM program

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs EWMP Final Work Plan 5.A 5 XX 2015 MCM 2012 Permit Requirement 2001 Permit Requirement Ordinances, policies, and procedures reflect IPM techniques and include commitments and schedules to reduce the use of pesticides that cause impairments Annually update in inventory of pesticides used by agency; quantify pesticides used by staff and contractors; demonstrate IPM alternatives to reduce pesticide use Use SOPs for pesticide application Store pesticides/herbicides/fertilizers indoors and apply only in accordance with label directions Ensure no application of pesticides or fertilizers when two or more days with a 50% chance of rain is predicted by NOAA; within 48 hrs of 1/2 inch of rain; or when water is flowing off the site Ensure staff applying pesticides are certified or working under supervision of a certified applicator in the appropriate category Update catch basin map add GPS locations and update priority 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. Designate Catch Basins as priority A, B, or C Required trash management at public events Ensure that Catch Basins (CBs) are cleaned appropriately Place and maintain trash receptacles/capture devices at newly identified high trash generating areas Place temporary screens on CBs prior to special events or cleanout immediately afterwards Place and maintain trash receptacles at all transit stops with shelters Designate curbed streets as priority A, B, or C based on liter accumulation Label storm drains (Required under PIPP in 2001) Inspect labels prior to each wet season Inspect the legibility of CB stencils and re label within 180 days if necessary Record and relabel illegible labels within 180 days of inspection Post signs at access points to water bodies (open channels, creeks; lakes) 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 Inspect and Remove trash and debris from open channels and other drainage structures 1x/yr before rainy season. Visually monitor and clean all open channels annually for debris Eliminate discharge of contaminants during MS4 maintenance Implement controls to limit infiltration of seepage from sanitary sewers to the storm drains Implement a sewer overflow prevention and response program Implement routine preventative maintenance for both systems, survey sanitary sewer and MS4. May use SSO General WDR to fulfill this requirement. Implement inspection and maintenance program for Permittee owned BMPs

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs EWMP Final Work Plan 5.A 6 XX 2015 MCM 2012 Permit Requirement 2001 Permit Requirement Manage residual water in treatment control BMPs removed during maintenance Street sweeping Priority A: 2x/mo; B: 1x/mo; C: as needed, not less than 1x/yr Implement road construction maintenance BMPs (e.g., restrict paving activity to exclude periods of rain) Inspect and/or clean Permittee owned parking lots 2x/mo Inspect and, if needed, clean Permittee owned parking lots twice per month, but at least once Train employees and contractors on stormwater requirements Train targeted employees in permit requirements for Public Agency Activities Train employees and contractors on pesticide use Recover saw cutting waste and dispose it offsite Conduct a dry weather diversion study and create a priority list of drains for diversion D.10 Illicit Connections and Illicit Discharges Elimination Continue IC/ID program Develop an Implementation Program which specifies how revisions of the IC/ID SQMP are implemented Create a database for permitted storm drain connections and map IC/ID Field screen the storm drain system for illicit connections in open channels Field screen the storm drain system for illicit connections in underground storm drains in priority areas Field screen the storm drain system for illicit connections in underground s/d larger than 36 inch diameter Review all permitted connections to the storm drain system for compliance Written procedures for conducting investigations and eliminations Initiate investigation within 72 hours from becoming aware of the discharge Respond to illicit discharges within one business day of discovery Investigate illicit discharges as soon as practicable Implement solutions to eliminate discharge; conduct follow up investigation to verify elimination; follow Progressive Enforcement Plan (see D.2) When discharge originates upstream of jurisdiction, notify the upstream jurisdiction and Regional Board within 30 days Initiate investigation within 21 days for illicit connection Investigate illicit connections 21 days after discovery Permit or document illicit connection that only discharge stormwater or allowed non stormwater Eliminate illicit connection within 180 days of investigation Terminate illicit connections 180 days after confirmation Facilitate public reporting via hotline Signage adjacent to open channels provide info re: public reporting Document calls and actions associated with hotline

Appendix 5.A Comparison of 2001 Permit MCMs to 2012 Permit MCMs MCM 2012 Permit Requirement 2001 Permit Requirement Implement procedures on responding to complaints; evaluate and update procedures Implement a spill response plan Train staff and contractors on ID/IC Create a list of positions and contractors that require ID/IC training Train targeted employees in the permit requirements for IC/ID Perform IC/ID Trend Analysis EWMP Final Work Plan XX 2015 5.A 7

Appendix 6.A Model Calibration and Parameters 6.A-1

Appendix 6.A Model Calibration and Parameters Table 6A-14. Regional Board model parameter ranges Hydrology Parameters Parameter Units Range of Initial Values Model Values Interception storage capacity in. 0.01-0.40 0.05-0.2 -- 0.01-0.15 0.1-0.2 Upper zone nominal soil moisture storage in. 0.05-2.0 0.5 Fraction of GW inflow to deep recharge -- 0.0-0.50 0.0 Fraction of remaining ET from baseflow -- 0.0-0.20 0.0 Fraction of remaining ET from active GW -- 0.0-0.20 0.0 Lower zone nominal soil moisture storage in. 2.0-15.0 7.0 Interflow inflow parameter -- 1.0-10.0 1.0 Interflow recession parameter -- 0.3-0.85 0.6-0.7 Lower zone ET parameter -- 0.1-0.9 0.25-0.6 Water Quality Parameters Initial storage of water quality constituent on land surface lbs 0.0-0.0005 0.0 Wash-off potency factor for sediment associated constituent lbs/ton 0.0-10.0 0.03-2.57 Scour potency factor for sediment associated constituent lbs/ton NA 0.03-2.57 Accumulation rate of water quality constituent of land surface lbs/ac/day 0.0-0.0005 n/a Maximum storage of water quality constituent on land surface lbs/ac/day 0.0-0.0005 n/a Rate of surface runoff that removes 90% of stored mass in/hr. 0.0-0.5 n/a General first order in-stream loss rate of constituent 1/day 0.2-0.2 0.1-0.2 Sediment Parameters Coefficient in the soil detachment equation -- 0.05-0.75 0.1-0.35 Exponent in the soil detachment equation -- 1.0-3.0 1.81 Coefficient in the sediment wash-off equation -- 0.1-10.0 0.35-0.85 Exponent in the sediment wash-off equation -- 1.0-3.0 2.0 Coefficient in the sediment scour equation -- 0.0-10.0 0.0 Exponent in the sediment scour equation -- 1.0-5.0 2.0 Solids accumulation rate on the land surface lbs/ac/day 0.0-30.0 0.003 Fraction of solids removed from land surface per day -- 0.01-1.0 0.025 Coefficient in the soil detachment equation -- 0.05-0.75 0.1-0.35 6.A-2

Appendix 6.A Model Calibration and Parameters Figure 6A-14. Daily flow at Ballona Creek below Sawtelle Blvd. (Station ID: F-38C). Figure 6A-15. Monthly flow at Ballona Creek below Sawtelle Blvd. (Station ID: F-38C). 6.A-3

Appendix 6.A Model Calibration and Parameters Figure 6A-16. Average monthly flow at Ballona Creek below Sawtelle Blvd. (Station ID: F-38C). Figure 6A-17. Monthly flow interquartiles at Ballona Creek below Sawtelle Blvd. (Station ID: F-38C). 6.A-4

Appendix 6.A Model Calibration and Parameters Figure 6A-18. Simulated vs. observed load duration plots for Total Sediment (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). Figure 6A-19. Simulated vs. observed timeseries plots for Total Sediment (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). 6.A-5

Appendix 6.A Model Calibration and Parameters Figure 6A-20. Simulated vs. observed load duration plots for Total Zinc (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). Figure 6A-21. Simulated vs. observed timeseries plots for Total Zinc (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). 6.A-6

Appendix 6.A Model Calibration and Parameters Figure 6A-22. Simulated vs. observed load duration plots for Total Copper (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). Figure 6A-23. Simulated vs. observed timeseries plots for Total Copper (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). 6.A-7

Appendix 6.A Model Calibration and Parameters Figure 6A-24 Simulated vs. observed load duration plots for Total Lead (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). Figure 6A-25. Simulated vs. observed timeseries plots for Total Lead (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). 6.A-8

Appendix 6.A Model Calibration and Parameters Figure 6A-26 Simulated vs. observed load duration plots for Total Lead (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). Figure 6A-27. Simulated vs. observed timeseries plots for Total Lead (10/1/2002 through 9/30/2011) at Ballona Creek Mass Emission Station (S01). 6.A-9

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures Draft 6B1-10

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures Ballona Creek Water Quality Model Development E. coli is the limiting pollutant for dry weather and thus the dry weather RAA focuses on demonstration that proposed dry weather BMPs will result in attainment of bacteria RWLs. The scenarios presented herein are very preliminary in terms of the actual design and operation of the North Outfall Treatment Facility (NOTF) for example, the scenarios assume 100% treat and release of intercepted flows, but it is possible that flows will be diverted to Hyperion Treatment Plant for water re-use in order to provide additional benefits. To simulate dry weather flow rates and bacteria concentrations in Ballona Creek, a QUAL2K model was applied. QUAL2K is a river and stream water quality model that is steady-state and onedimensional (assumes complete mixing vertically and laterally) 7. Originally developed in the late 1980s, the QUAL2K framework is supported by USEPA and has been applied to thousands of watersheds and TMDLs. QUAL2K was developed to simulate a longitudinal profile of E. coli within Ballona Creek. E. coli was used as a surrogate for all other bacterial indicator objectives, because it is an objective in Ballona Creek Reach 2 and Sepulveda Channel, and because it has been assumed to be functionaly equivalent to fecal coliform, the indictor used to evaluate compliance with REC-2 standards in Ballona Creek Reach 1 and Marine REC-1 standards in Ballona Estuary. Boundary Conditions for Model Set-up The boundary conditions for simulating Ballona Creek water quality were based on three sources of data: 1. July 2012 Recon, which measured flows and concentrations along the entire length of 2. Ballona Creek Bacteria TMDL Coordinated Monitoring Plan 3. The applied boundary conditions and data sources are shown in Table 6B1-1. Note that dry weather flow rates for these segments were based on the total measured storm drain flow during the recon, and the applied concentrations were the flow-weighted averages. The time for downstream travel is a key parameter for bacteria fate and transport. The in-stream travel times along the Ballona Creek mainstem were based on measurements collected during the Ballona Creek Flux Study (Noble et al., 2006). The study deployed open-channel flow meters in the Ballona Creek watershed to measure depth and velocity rates at one-minute intervals over a 6-hour period. The velocities measured with open channel flow meters during the Flux Study were a valuable resource, as velocities could be inserted directly into the model as boundary conditions (instead of mainstem Ballona Creek were applied to the corresponding segments, as shown in Figure 6B1-1. Segment lengths were measured using ArcGIS software. 7 See http://epa.gov/athens/wwqtsc/html/qual2k.html Draft 6B1-11

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures E. coli was simulated in the QUAL2K model as a non-conservative parameter with first-order, exponential decay. The applied decay rate was 0.09 per hour, which is the decay rate used in the LA River Bacteria TMDL (CREST, 2010). This decay rate was derived from SCCWRP decay studies that employed sunlight and temperature conditions specific to southern California (Noble et al., 2004). Table 6B1-1 Boundary Conditions for the QUAL2K Model and Data Sources FLOW RATE E. coli CONCENTRATION Boundary Location Flow Rate (cfs) Data Source Concentration (MPN/100mL) Data Source Cochran Ave Daylight 7.1 2012 Recon 720 2012 Recon Wed_07 Tunnel Daylight 5.9 2012 Recon 460 2012 Recon Adams Drain 0.3 2012 Recon 1900 2012 Recon Benedict Canyon Channel 3.54 2012 Recon 630 Sepulveda Channel 1.54 2012 Recon 1400 Diffuse inputs between Wed_07 and National Blvd Diffuse inputs between National Blvd and Tue_13 Diffuse inputs between Tue_04 and Tue_11 Diffuse inputs between Tue_01 and Tue_02 CMP and Status & Trends median CMP and Status & Trends median 3.2 2012 Recon 2162 2012 Recon 1.1 2012 Recon 1225 2012 Recon 0.5 2012 Recon 760 2012 Recon 0.2 2012 Recon 174 2012 Recon Diffuse inputs to Sepulveda Channel 0.0 2012 Recon N/A 2012 Recon Draft 6B1-12

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures Figure 6B1-1 Travel Times used in QUAL2K based on Velocities Measured during the Flux Study (v = median velocity, L = segment length, t = segment travel time during dry weather) Model Verification for Baseline Conditions Once the QUAL2K model was setup with the previously described boundary conditions, the predicted flow rates and E. coli predict current/baseline conditions, as follows: The simulated dry weather flow rates in Ballona Creek are shown in Figure 4-2. The simulated flow rate at Sawtelle Avenue, 16.3 cfs, is consistent with the observed median 8 daily flow rate 8 Application of a median flow rate for the dry weather TMDL analysis is consistent with the LA River Bacteria TMDL (CREST, 2010). Draft 6B1-13

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures from the 1978-2011 LA County DPW flow gage, 15.0 cfs. The difference in predicted and observed flow rate at Sawtelle Avenue was less than 8.7 percent. The simulated E. coli concentrations in Ballona Creek during dry weather are shown in Figure 6B1-2. The simulated E. coli concentration at Centinela Avenue, 613 MPN per 100 ml, is consistent with the observed median from the historic data at BCB-5, 630 MPN per 100 ml 9. The difference in predicted and observed E. coli concentration at Centinela Avenue was less than 2.7 percent. The results demonstrate the QUAL2K model is able to represent current water quality conditions in Ballona Creek, which will serve as the basis for evaluating potential EWMP implementation scenarios, as described in the next section. 9 Based on 287 samples collected between 2004 and 2011 during the Status & Trends and CMP monitoring from Inglewood Avenue, which is approximately 1500 feet upstream of Centinela Avenue. Draft 6B1-14

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures Figure 6B1Modeled Baseline Conditions Flow Rate (top) and E. coli Concentrations (bottom) Draft 6B1-15

Appendix 6.B1 Dry Weather RAA for E.coli Control Measures Modeling of BMP Implementation Scenarios for Ballona Creek The verified QUAL2K model provides the quantitative basis for evaluating potential BMP implementation scenarios and providing reasonable assurance that proposed BMPs will result in attainment of applicable E. coli RWLs. The considered scenarios and predicted water quality outcomes are described in the following sub-sections. Considered BMP Implementation Scenarios The effect of two BMPs was simulated for the EWMP Implementation Plan, as follows: NOTF for Ballona Creek Reach 2: the purpose of the North Outfall Treatment Facility would be to reduce E. coli concentrations in Reach 2 to levels below the Limited REC-1 WQOs and also reduce impacts of Reach 2 on the Estuary. The model assumed the NOTF will extract dry weather flow from Ballona Creek, disinfect to reduce levels to 20 MPN per 100mL, and return the flows the channel. The scenario presented herein is very preliminary in terms of the actual design and operation of the North Outfall Treatment Facility (NOTF) for example, the scenarios assume 100% treat and release of intercepted flows, but it is possible that flows will be diverted to Hyperion Treatment Plant for water re-use in order to provide additional benefits. Treatment Facility for Sepulveda Channel prior to daylight: Sepulveda Channel is designated as a REC-1 waterbody, even though it is a vertical walled box channel with limited access. The first purpose of the Sepulveda Channel low flow treatment facility (LFTF) prior to the daylight location would be to reduce E. coli concentrations to levels below REC-1 WQOs. The second purpose of the facility would be to prevent the Sepulveda Channel discharge from causing WQO exceedances in lower Reach 2 of Ballona Creek. The model assumed the Sepulveda Channel LFTF will remove all Sepulveda Channel flows prior to discharge to Ballona Creek. If treatment was utilized instead of the diversion, the conclusions of this dry weather RAA would not be affected. Results of BMP Implementation Modeling The combination of the NOTF and Sepulveda Channel LFTF has reasonable assurance of attaining E. coli RWLs in Ballona Creek prior to the freshwater confluence with the Estuary. As shown in Figure 6B1-3, the QUAL2K model predicts that concentrations of E. coli will be below the Limited REC-1 geometric mean WQO (126 MPN/100mL) downstream of NOTF for the entire extent of the non-tidally influenced channel. In Reach 1, the geometric mean fecal coliform concentration is less than the REC- 2 geometric mean WQO of 2000 MPN per 100mL, and thus no BMPs are needed upstream of the Reach 1/Reach 2 break to achieve RWLs during dry weather (assuming a 1:1 translator between E. coli and fecal coliform). Summary of BMP Implementation Modeling The QUAL model outputs shown in Figure 6B1-3 constitute the reasonable assurance analysis to demonstrate that NOTF and Sepulveda Channel LFTF will achieve RWLs in Ballona Creek Reach 2. The concentrations of fecal coliform in Reach 1 are currently below the RWL, based on historic monitoring data. The QUAL model has provided a robust tool to conduct the dry weather RAA for the Ballona Creek EWMP. 6.B1-1

Section 6.B1 Dry Weather RAA and Non-Stormwater Analysis 16.00 5.80 7.10 REACH 1 REACH 2 ESTUARY 5.59 0.40 Centinela Blvd. 4.77 5.90 Sepulveda Channel 14.00 4.05 8.17 2.65 10.12 2.27 0.29 0.55 14.16 12.00 0.00 14.36 Benedict Canyon 10.00 Cochran Daylight Adams Drain 8.00 Flow (cfs) Tunnel Daylight 6.00 4.00 Tunnel Start 6.0 5.0 Cochran Daylight Tunnel Start 4.0 3.0 NOTF Distance Upstream (miles) 2.0 1.0 Flows (cfs) 2.00 0.00 0.0 REACH 1 REACH 2 ESTUARY Tunnel Daylight E. coli (MPN/100mL) Adams Drain Benedict Canyon 1200 1000 800 600 400 Concentration (MPN/100mL) 1 LREC-1 Geometric Mean WQO < 126 MPN / 100mL 200 NOTF Centinela Blvd. 6.0 5.0 4.0 3.0 Distance Upstream (miles) 2.0 Sepulveda Channel 1.0 0 0.0 Figure 6B1-3 Predicted Flow Rates (top) and E. coli Concentrations (bottom) with Implementation of NOTF and Sepulveda Channel LFTF (subject to change based on actual NOTF design) 6.B1-2

Appendix 6.B2 Dry Weather RAA and Non-Stormwater Analysis 6.B2-1

Section 6.B1 Dry Weather RAA and Non-Stormwater Analysis This appendix presents the simulation of non-stormwater and dry weather reasonable assurance analysis (RAA) for the EWMP. Introduction The MS4 Permit effectively prohibits discharges of non-stormwater 10 (dry weather runoff) and states -stormwater discharges that are effectively prohibi limitations (WQBELs) for some of the applicable total maximum daily loads (TMDLs) including the Los Angeles River metals TMDL. However, it is important that dry and wet weather conditions not be evaluated in separate silos the EWMP includes a large network of wet weather BMPs that will eliminate a majority of non-stormwater discharges. As presented herein, the non-stormwater simulation quantifies the reduction of wet weather BMPs on non-stormwater discharges, and the remaining amount to be addressed will be achieved by non-stormwater abatement programs including source investigation/elimination and regional water use reduction efforts. The non-stormwater analysis and dry weather RAA are presented as follows: Methodology and validation for non-stormwater simulation (Section 2) Results of non-stormwater simulation (Section 3) Dry weather RAA (Section 3) Non-stormwater Simulation Approach The primary source of non-stormwater is outdoor water use. As such, the non-stormwater analysis is based on a simulation of non-stormwater whose source is outdoor water use11 in each of the subwatersheds within the EWMP area and whose sink is evapotranspiration and incidental infiltration. The modeling approach used for the non-stormwater analysis is distinctly different from the wet weather RAA with the wet weather RAA being process-based (build-up wash off) and the dry weather RAA being a steady-state simulation based on empirical water use data from southern California. The non-stormwater analysis and wet weather RAA are linked by estimating the effectiveness of wet weather control measures on non-stormwater flows. The methodology and validation are presented in the subsections below. Methodology The methodology for the non-stormwater analysis is presented in the following subsections. 10 Non-stormwater does not include all dry weather runoff. For example, permitted dry weather discharges (e.g., dewatering) and groundwater baseflow are exempted/allowed by the Permit. 11 Non-stormwater volumes are not necessarily equal to dry weather runoff volumes in the EWMP area. Non-stormwater is the portion of dry weather runoff that is effectively prohibited by the Permit. Dry weather runoff would also include groundwater that is discharged through the MS4 system (if any), which is allowed by the Permit. By focusing on the nonstormwater portion of dry weather runoff, the non-stormwater analysis and dry weather RAA are focused on the portion of dry weather runoff that is required to be controlled by MS4s. 6.B2-2