Conceptual Model to Support PCB Management and Monitoring in the Emeryville Crescent Priority Margin Unit

San Francisco Estuary Institute (SFEI) | April 3rd, 2017

The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the PCB Synthesis Report (Davis et al. 2014) pertaining to: 

The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the PCB Synthesis Report (Davis et al. 2014) pertaining to:  1. identifying margin units that are high priorities for management and monitoring,  2. development of conceptual models and mass budgets for margin units downstream of watersheds where management actions will occur, and  3. monitoring in these units as a performance measure.  The goal of the effort is to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional Permit for Stormwater (MRP), both of which are tentatively scheduled to occur in 2020. Conceptual model development for four priority margin units (PMUs) that are high priorities for management and monitoring will provide a foundation for establishing effective and efficient monitoring plans to track responses to load reductions and will also help guide planning of management actions. The Emeryville Crescent (the Crescent) is the subject of this report and the first PMU to be studied. 

Conceptual Model to Support PCB Management and Monitoring in the San Leandro Bay Priority Margin Unit Final Report

San Francisco Estuary Institute (SFEI) | November 2nd, 2019

The goal of this report is to answer three questions related to management and monitoring of PCBs in priority margin units. To this end, a conceptual model was develope

The goal of this report is to answer three questions related to management and monitoring of PCBs in priority margin units. To this end, a conceptual model was developed that includes four major elements: 1. loading from the watersheds; 2. initial deposition and retention; 3. processes determining the long-term fate of PCBs in sediment and water; and 4. bioaccumulation in the food web

Conceptual Model to Support PCB Management and Monitoring in the San Leandro Bay Priority Margin Unit, Phase One

San Francisco Estuary Institute (SFEI) | June 1st, 2018

The goal of RMP PCB special studies over the next few years is to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional P

The goal of RMP PCB special studies over the next few years is to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional Permit for Stormwater, both of which are tentatively scheduled to occur in 2020. Conceptual model development for a set of four representative priority margin units will provide a foundation for establishing an effective and efficient monitoring plan to track responses to load reductions, and will also help guide planning of management actions. The Emeryville Crescent was the first PMU to be studied in 2015-2016. The San Leandro Bay PMU is second (2016-2017), Steinberger Slough in San Carlos is third (2017), and Richmond Harbor will be fourth (2018). The conceptual model reports for these four PMUs will be developed and presented using a consistent framework, and will build on each other to form an integrated assessment of these four areas. The lessons learned from these analyses will also be more generally applicable to similar contaminated sites on the margins of the Bay.

Demonstration of a Watershed Approach to Wetland Restoration Planning for Load Reductions: A Pilot Demonstration Project Using GreenPlan-IT in the Santa Rosa Plain, Sonoma County, California

San Francisco Estuary Institute (SFEI) | December 30th, 2017

This summary memorandum presents technical recommendations to the 401 Certification and Waste Discharge Program (401 Program) of the State Water Resources Control Board (

This summary memorandum presents technical recommendations to the 401 Certification and Waste Discharge Program (401 Program) of the State Water Resources Control Board (State Board) for a coherent, scientifically sound, repeatable, watershed approach to wetland restoration site evaluation, compliance monitoring and assessment, and Tracking. The recommendations are drawn from the previous four memoranda produced for the Pilot Demonstration Project (Project) that address the following subjects: project work plan and information flow diagram; scientific literature review; landscape scenario planning (to map and prioritize restoration opportunities); and a framework for a watershed-approach to evaluate and report the capacity of a wetland restoration site to protect wetland beneficial uses. This Project focused on a sub-watershed of the Santa Rosa Plain, in Sonoma County, California. The area was chosen for the Project for three reasons: (1) it is integral to an existing nutrient TMDL and therefore is supported relatively well with hydrological and nutrient data; (2) the historical and existing wetlands and streams of the area were mapped recently in sufficient detail to inform landscape planning; and (3) implementation of the TMDL will involve wetland restoration to reduce downstream nutrient loads, and therefore the Project may help implement the TMDL. The primary overall purpose of this Project was to explore how numerical simulation and statistical modeling could be combined with existing wetland assessment and reporting tools to create a coherent, watershed-based approach to wetland beneficial use protection. Any relevance to the existing nutrient TMDL for the demonstration area is an intentional, but secondary benefit of this Project. Contents: Wetland Beneficial Use Protection: Pilot Demonstration Project A Synthesis of Literature on Wetland Assimilation Capacities, Models, and Pollutant Loads Simulating Wetland Assimilation Capacity in the Lower Santa Rosa Creek Watershed Pilot Demonstration Area Using the HSPF Model Demonstration of a Watershed Approach To Wetland Restoration Planning Using GreenPlan-IT

Downstream Effects of Stormwater Management Basins

American Society of Civil Engineers (ASCE) | June 1st, 1979

Urbanization decreases the natural storage of a watershed, which changes the timing characteristics of the runoff. Stormwater management (SWM) basins are an attempt to pu

Urbanization decreases the natural storage of a watershed, which changes the timing characteristics of the runoff. Stormwater management (SWM) basins are an attempt to put the storage lost through development back into the runoff process. While SWM basins provide the proper volume of storage, they fail to return the timing characteristics to those that existed prior to development. The changes in storage and timing characteristics may have adverse effects on flow rates and bedload transport in downstream channel reaches. A study of a 2.12-sq mile watershed in Montgomery County, Md., showed that a SWM basin increased both peak flows and bedload transport rates in the channel downstream from the facility. This results from both the change in timing characteristics and the increased duration of bankfull flow. These results indicate that SWM policies must require evaluation of SWM plans on a regional basis and not just using on-site control criteria. Also, methods that can evaluate storage and timing changes must be used in the design of SWM facilities.

Environment California, Inc. v. City of Los Angeles

Holmes, Athey, Cowan & Mermelstein LLP | July 23rd, 2024

Equity in Stormwater Investments: Measuring Community Engagement and Disadvantaged Community Benefits for Equitable Impact in the Safe Clean Water Program

Publisher not available | August 4th, 2022

The Safe, Clean Water Program (SCWP) reflects the will of the voters of Los Angeles County, who approved Measure W in 2018 by close to 70%. The ballot measure established

The Safe, Clean Water Program (SCWP) reflects the will of the voters of Los Angeles County, who approved Measure W in 2018 by close to 70%. The ballot measure established a perpetual parcel tax “to fund projects and programs to increase stormwater capture and reduce stormwater and urban runoff pollution” in Los Angeles County “to increase water supply, improve water quality, and, where appropriate, provide community enhancements such as the greening of schools, parks, and wetlands, and increased public access to rivers, lakes, and streams.” In an ordinance implementing the Safe Clean Water Program, the county Board of Supervisors included provisions to prioritize equity in implementation and affirmed an intention to address inequity in infrastructure in August 2021. Those provisions gave rise to this report, which provides advice drawn from research and stakeholder engagement to the Los Angeles County Flood Control District (LACFCD) for measuring community engagement and Disadvantaged Community Benefits to better achieve the equitable impact sought by the SCWP. As part of a broader SCWP Metrics and Monitoring Study (MMS) commissioned by the LACFCD, we were charged with conducting research, consulting with stakeholders, and giving advice to the SCWP for metrics to measure community engagement and Disadvantaged Community Benefits.

Estimating Monetized Benefits of Groundwater Recharge from Stormwater Retention Practices

U.S. Environmental Protection Agency (EPA) | February 4th, 2016

Stormwater impacts from development have been documented extensively in peer-reviewed literature and summarized in the National Research Council’s report titled Urban S

Stormwater impacts from development have been documented extensively in peer-reviewed literature and summarized in the National Research Council’s report titled Urban Stormwater Management in the United States (National Research Council, 2009). To address these impacts, the U.S. Environmental Protection Agency (EPA) Office of Water (OW) evaluated several potential scenarios for managing stormwater from new development and redevelopment using small stormwater retention practices. The objective of these practices is to reduce runoff volume to simulate pre-development hydrology and protect water quality. These practices are often designed to infiltrate the retained water, which can provide groundwater recharge to help maintain predevelopment groundwater levels. For the purposes of this study, infiltration was assumed, whereas in practice capture-and-use or other methods also may be applied. The purpose of the study is to inform valuation of groundwater recharge from stormwater retention in areas projected for new development and redevelopment. Retention practices can prevent the loss of natural recharge that may occur on a developed site without these practices. This study examined a simplified methodology for estimating recharge volume and used observed prices of water for monetary valuation. Groundwater recharge is just one benefit within the larger context of the costs and benefits of stormwater retention practices. The full range of potential benefits were not addressed in this study, but the full suite of benefits should be considered when comparing to an estimated cost of implementation. Costs of implementing retention practices in areas of new and redevelopment also were not addressed in this study. The estimates represent the groundwater recharge volume and value that would result if stormwater retention practices were implemented in areas within the contiguous U.S. not currently requiring stormwater retention. The stormwater retention practices were assumed to capture a specified depth of runoff, in the range of 0.5 to 2 inches (i.e. not large storm attenuation) with a goal of reducing runoff volumes to levels similar to those for pre-developed landscape conditions. This approach is commonly referred to as “green infrastructure” for stormwater management or low impact development (LID). While small storm retention that approximates predevelopment runoff could also be achieved with cisterns in those areas where infiltration is not desired or is not feasible, the option of cistern capture was not evaluated in this study. The timeframe selected for the purpose of the predictive study was the 20-year period of 2021 through 2040.

Estuary News, April 1993

Publisher not available | April 15th, 1993

Estuary News, April 1997

San Francisco Estuary Partnership (SFEP) | April 15th, 1997