Contaminants at the Estuary Interface Jon Leatherbarrow 1 Rainer Hoenicke 2 Lester McKee 1 1 San Francisco Estuary Institute 2 California Resources Agency

Estuary Interface Pilot Study History EIP study initiated with the goal of describing how surface runoff from local watersheds might influence water quality in the Bay. Final report – Available soon

Objectives Relate patterns of contamination near the bottom of the watersheds to patterns in the receiving waters of the Lower South Bay Explore what kinds of water quality parameters and watershed characteristics should be measured or described to improve tributary monitoring methodology

Sampling Design Water - three samples per year Sediment - two samples per year Parameters Trace Elements Organics – PCBs, PAHs, Pesticides Water and sediment quality parameters

Conclusions Concentrations of PCBs, PAHs, mercury, selenium, DDTs, and chlordanes were high in water and/or sediment collected from one or both of the EIP stations relative to several other Bay segments. High wet-season concentrations in EIP water samples suggest that the tributaries were a likely pathway for all of these contaminants to the Lower South Bay. Mercury concentrations in Guadalupe River (BW15) water and sediment were most likely influenced by the historic mining activities in the New Almaden district. Several independent factors, such as TSS in the water column and grain size effects in sediment, account to some extent for variability in contaminant concentrations.

RMP Five-Year Review New RMP Objective Describe general sources and loadings of contamination to the Estuary RMP Sources Pathways and Loadings Workgroup

Further Questions How do contaminant concentrations vary during conditions of peak streamflow and sediment transport? What is the magnitude of contaminant loading from the local watersheds? How does loading from the tributaries compare to other pathways of contamination? What are the specific sources of contamination in the local watersheds? What are the most effective management actions?

Next Steps Develop network of tributary monitoring locations in the fresh water reaches of selected watersheds. Prioritize locations based on conceptual models, recent and historic contaminant data, and watershed characteristics. Design monitoring to capture contaminant response to peak flow and sediment transport and quantify loading from the watersheds. Explore and develop indicators for determining sources and temporal trends in contaminant concentrations and loading. Compare watershed loading with other pathways of contamination in the context of refined mass budgets for contaminants of concern.

Acknowledgments City of San Jose and Santa Clara Valley Urban Runoff Pollution Prevention Program (SCVURPPP) RMP Principal Investigators and Contractors Applied Marine Sciences Brooks Rand Laboratories City and County of San Francisco East Bay MUD Texas A&M – Geochem. and Environ. Research Group UC Santa Cruz – Dept. of Environmental Toxicology University of Utah – Energy and Geoscience Institute Jay Davis, Don Yee, and members of the RMP Sources, Pathways, and Loadings Workgroup All reviewers of the EIP Study report