San Francisco Bay is a highly productive, economically important, highly modified, and vulnerable estuarine ecosystem. For over 150 years, the Bay has undergone extensive modification, including damming and channelization of upstream rivers, navigation dredging, sand mining, tidal marsh removal for commercial salt production, urbanization, and flood control measures. There have also been wholesale ecological changes, with over 100,000 acres loss of tidally influenced areas along the Bay shoreline. Currently, about half of the watershed area that drains to the Bay is dammed for water supply and flood protection, trapping large volumes of sediment including sand, a portion of which would have otherwise been transported to the Bay. Furthermore, there are concerns that the commercial mining of sand in the Bay could be exacerbating net erosion of beaches and could lead to alterations of tidal wetland and subtidal habitats.
From 2021-2023, SFEI worked with BCDC and scientists from the USGS and Deltares to develop an understanding of contemporary sand transport dynamics within the Bay and the associated influence sand mining may have on sand-reliant landscape and habitat features within the Bay and the nearby outer coast. The questions driving this research were:
- Is sand mining at existing lease areas, at permitted levels, having a measurable or demonstrable impact on sediment transport and supply within San Francisco Bay or the outer coast?
- What are the anticipated physical effects of sand mining at permitted levels on sand transport and supply to San Francisco Bay and the outer coast?
- Are there other feasible sand mining approaches to consider in San Francisco Bay?
The team produced a series of technical reports describing current Bay sand supply from the Central Valley and from local tributaries, current Bay floor sand erosion and deposition dynamics, contemporary baywide and subembayment-scale sand budgets, and sand transport dynamics directly adjacent to commercial sand mining areas. The reports were reviewed and vetted by a Sand Technical Advisory Committee made up of regional stakeholders and an Independent Science Panel made up of renowned experts in Bay sediment transport dynamics. The project findings will be used to inform future sand mining permit conditions.
Technical Reports
Sand Budget and Sand Transport in San Francisco Bay: Full Report and Executive Summary
Supporting Research
- Literature review and synthesis
- Sand supply to San Francisco Bay from the Sacramento and San Joaquin Rivers of the Central Valley, California
- Sand supply to San Francisco Bay from the local tributaries in the nine urbanized counties that ring the Bay
- Net sand storage/removal from local tributary flood control channels in the nine county Bay Area
- Contributions of erosion, deposition, and human activities to a change in sand storage in the bed of San Francisco Bay, California
Sand Transport Study
Information Management
Other Resources
Findings from the full suite of technical studies for this project
Other Individual Contributors
To Save the Bay, Save its Sediment
Sand and mud are the essential building blocks for the Bay's shoreline to keep pace with sea level rise. But San Francisco Bay is losing 1.7 million metric tons more of sand and mud per year than it's gaining—more than double the weight of the Golden Gate Bridge. Sand mining and other human extraction are major drivers of the Bay’s sand deficit.