Sources, Pathways, & Loadings (RMP Workgroup)

Urban Runoff Degrades Bay Water Quality

The RMP Sources, Pathways, and Loading Workgroup (SPLWG) was formed in 1999 to make recommendations for collection, interpretation, and synthesis of data on sources and amounts of contaminants entering San Francisco Bay. This information supports efforts to identify and eliminate pollution in the landscape, and prevent it from harming San Francisco Bay.

The First Two Decades

During the first decade, the workgroup used a field-intensive monitoring program to estimate loads of PCBs, mercury, and other legacy contaminants entering the Bay. We monitored multiple pathways including the Sacramento and San Joaquin Rivers, urban and nonurban stormwater from the nine Bay Area counties, municipal and industrial wastewater, and atmospheric deposition.

With PCB and mercury cleanup plans in place, the second decade focused on improving our understanding of PCBs and mercury fate and transport, monitoring municipal stormwater, and building modeling tools to estimate regional loads and trends over time. We also worked to identify the locations in the watershed that contribute most to impairing Bay water quality.

Photo: Kyle Stark

Our Current Work

Now in its third decade, the SPLWG focuses on emerging contaminants in stormwater, and on developing an integrated monitoring and modeling approach for both legacy and emerging contaminants to address RMP management questions more efficiently.

Spotlight on Recent Work

Bay-wide Watershed Dynamic Model

The Watershed Dynamic Model, a hydrologic model for the Bay Area, can predict flow and sediment for 1994-2024. The model simulates the nine Bay Area counties, with mixed land use types, a wide range of pollutants, upland erosion and sediment transport, and in-stream processes (e.g., bank erosion, settling, and resuspension). The completed model performs well. It can reproduce the timing and peaks of runoff events as well as the annual and year-to-year variation of flow and sediment loads.
Stormwater Monitoring for PCBs and Mercury

Since 2011, the RMP has collaborated with county stormwater programs to fund watershed reconnaissance of PCBs and mercury and identify especially polluted watersheds within larger areas of older urban and industrial land use. Recently, more intensive data collection has focused on three watersheds in the region to help calibrate the Watershed Dynamic Model. These monitoring efforts will soon include a new remote sampler in tidal areas downstream from suspected PCB sources.

Science Advisors

The scientific advisory panel for the Bay RMP Sources, Pathways, and Loadings Workgroup consists of internationally renowned experts:

SFEI Lead Scientists

For more information, please contact Alicia Gilbreath at [email protected] or Matthew Heberger at [email protected].

Featured RMP Projects

Emerging Contaminants in Urban Stormwater Runoff

Rain-driven flows from city streets and storm drains transport PFAS and other contaminants to the Bay, degrading water quality. The Regional Monitoring Program recently completed four years of stormwater monitoring and found widespread PFAS contamination. Little is… Read More

Regional Watershed Spreadsheet Model

The Regional Watershed Spreadsheet Model (RWSM) was developed to estimate average annual regional and sub-regional scale loads for the San Francisco Bay Area. It is part of a class of deterministic empirical models based on the volume-concentration method.

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