Conceptual Understanding of Fine Sediment Transport in San Francisco Bay

Sediment is a lifeblood of San Francisco Bay. It serves three key functions: (1) create and maintain tidal marshes and mudflats, (2) transport nutrients and contaminants, and (3) reduce impacts from excessive human-derived nutrients in the Bay. Because of these important roles, we need a detailed understanding of sediment processes in the Bay.

The Conceptual Understanding of Fine Sediment Transport in San Francisco Bay report provides a conceptual-level, common understanding of how fine-grained sediment (i.e. silt and finer) moves around at different scales within the Bay to synthesize the current state of information while also identifying the key data gaps in need of more research. To do this, this report first considers overarching sediment pathways that supply sediment to the entire Estuary and then identifies more specific pathways for the baylands in the Bay, a subwatershed of the larger Estuary, between the Golden Gate and the western boundary of the Sacramento-San Joaquin Delta at Broad Slough. 

This report:

• Describes a conceptual understanding of open-Bay sediment processes at the Bay and subembayment scale (Chapter 2)
• Describes a conceptual understanding of sediment processes at the baylands scale (Chapter 3)
• Summarizes key knowledge gaps, with an emphasis on fine-sediment supply for baylands habitat support, and provides recommendations for future studies for the San Francisco Bay region (Chapter 4)

The objective of this report is to inform future San Francisco Bay Regional Monitoring Program (RMP) work under the guidance of the Sediment Workgroup of the RMP for Water Quality in San Francisco Bay, which brings together experts who have worked on many different components of the landscape, including watersheds and tributaries, marshes and mudflats, beaches, and the open Bay. Findings can also help to improve communication and collaboration between restoration practitioners, regulators, policymakers and other key stakeholders to help identify and drive forward necessary sediment management actions given the pressures of climate change.