POLLUTANTS OF CONCERN

“Pollutants of Concern” (or POCs) refers to two broad categories of concern:

1) Pollutants that impair water quality such as mercury and polychlorinated biphenyls (PCBs) have established plans to reduce loading over time to levels no longer impairing uses of the San Francisco Bay and other regional waterways. These plans are critical due mercury and PCBs presence in fish at levels limiting human consumption. These impacts can be traced to legacy contamination within watersheds pouring into the San Francisco Bay. Low levels of legacy pollutants like mercury and PCBs are a long-standing stormwater management challenge in many urban communities. The MRP requires aggressive control measures to reduce these pollutants, supported by monitoring plans to identify potential sources and evaluate the effectiveness of corrective measures.

2) Pollutants such as copper and contaminants of emerging concern that have multiple sources, including urban stormwater, and warrant investigative monitoring due to their potential to impair water quality. Monitoring helps support regional models that need to account for stormwater loads and provide updated evidence that impairments are not occurring. 

3) Mercury and methylmercury water sampling specific to Region 5 waterbodies. This includes the West Delta, Marsh Creek, and Central Delta subareas.

Key Documents:

Old Industrial Control Measure Plan:

MRP 3.0 Provision C.12.c requires the Permittees, within the permit term, to implement or cause control measures to be implemented (i.e., treatment controls, diversion to wastewater treatment plants, green stormwater infrastructure (GSI), enhanced operation and maintenance controls, or other controls) to achieve PCBs load reductions. The CCCWP submitted an Old Industrial Area Control Measure Plan (CMP) as required by MRP 3.0 Provision C.12.c on March 31, 2023. CCCWP revised the March 2023 CMP to address SFBRWQCB comments and submitted the revised plan on April 1, 2024. The CMP provides a plan and schedule for focused implementation of control measures in old industrial areas to address PCBs load reduction requirements.

• Old Industrial Area Control Measure Plan (PDF)

Major planning reports for mercury and PCBs summarize lessons learned and set expectations for future permits: 

CCCWP’s Mercury and PCBs Total Maximum Daily Load (TMDL) Control Measure Plan and Reasonable Assurance Analysis shows the approach Permittees will follow to achieve pollutant load reduction goals. A TMDL plan sets goals for reducing pollutants from all sources and conveyances, including stormwater. Controlling these legacy pollutants in urban stormwater requires pollution prevention, source identification and reduction, and treatment by both Green Stormwater Infrastructure (GSI) and enhanced maintenance of trash and sediment capture devices. The sections of this report show how the complete program of control measures will achieve load reduction goals over time and summarize the costs and challenges of plan implementation. 

• The main body of the report summarizes control measures, the implementation approach, the technical basis for expected benefits, and metrics successful implementation (PDF). 
• Appendix A, the Reasonable Assurance Analysis (RAA), uses stormwater models to forecast the time frame to achieve load reduction goals (PDF).
• Appendix B, the Source Control Loads Reduction Accounting for RAA,  presents details of the accounting metrics translating control measures to loads reduced (PDF).
• Appendix C, the Conceptual Work Plan for PCB Source Area Assessment, shows the approach for investigating watersheds for potential properties that may be current PCB sources to the municipal storm drain system (PDF).
• Appendix D, the PCBs in Building Material Screening Assessment Package, defines the process for Permittees to guide the managers of building demolition projects to inspect for and remove PCB-containing building materials (e.g., caulk) prior to demolition (PDF).
• Appendix E provides regional guidance for conducting source area assessments (PDF). 
• Appendix F outlines a methodology for estimating costs of GSI implementation (PDF).
• Appendix G describes scenarios for attaining required PCB loads over time (PDF).
• Appendix H summarizes the findings of a technical peer review of the RAA report (PDF).

2026 update to CCCWP’s Mercury and PCBs TMDL Control Measure Plan and Reasonable Assurance Analysis. This update revises and replaces the 2020 plan by evaluating current control measure effectiveness, updating projected load reductions, and confirming compliance with Municipal Regional Stormwater Permit Provisions C.11.f.iii and C.12.h.iii. It provides an updated basis for demonstrating reasonable assurance of meeting PCBs and mercury TMDL requirements, incorporating new data, refined analyses, and revised implementation expectations for the upcoming MRP 4.0 term.

• Contra Costa County Mercury and PCBs TMDL Control Measure Plan and Reasonable Assurance Analysis 2026 Update

• Appendix A presents the results of the RAA for Contra Costa County

Annual summaries of monitoring performed for POCs are provided as appendices to each annual Urban Creek Monitoring Report. A list of Archived Urban Creeks Monitoring Reports can be found within the CCCWP Monitoring and Assessment webpage. These appendices report on work performed directly by CCCWP.  The complete contents of all annual UCMRs, including appendices, are also available at this link.

• 2022 Pollutants of Concern Monitoring Report (PDF)
• 2021 Pollutants of Concern Monitoring Report (PDF)
• 2020 Pollutants of Concern Monitoring Report (PDF)
• 2019 Pollutants of Concern Monitoring Report (PDF)
• 2018 Pollutants of Concern Monitoring Report (PDF)
• 2017 Pollutants of Concern Monitoring Report (PDF)
• 2016 Pollutants of Concern Monitoring Report (PDF)
• The 2015 Pollutants of Concern Monitoring summary (PDF) described a regional approach to stormwater characterization led by the San Francisco Estuary Institute and updated progress on the Delta Methylmercury Control Study. In addition to nutrients and copper monitoring, studies led by CCCWP included:
  • Sediment screening to identify potential PCB source properties (PDF)
  • Evaluation of a pilot project to divert urban runoff into sanitary sewers to remove PCBs and mercury (PDF)