Providing new support for Baykeeper’s work to prevent excessive sand mining in San Francisco Bay, recent scientific research confirms the link between removing too much sand from the Bay’s floor and excessive erosion at San Francisco’s Ocean Beach.
The journal Marine Geology’s November 2013 special issue on sediment transport research includes several papers on how sand naturally moves into and out of San Francisco Bay, most of them the work of scientists at the US Geological Survey (USGS). The researchers have identified dredging and sand mining in the Bay as directly limiting the amount of sand that washes from the Bay onto Ocean Beach and beaches further south, from around Noriega Street in San Francisco and extending south to the city of Pacifica.
These research findings provide validation for Baykeeper’s lawsuit to stop the State Lands Commission, which issues leases for sand mining on the Bay’s floor, from significantly increasing the amount of sand that can be removed from the Bay. In deciding to allow a large increase in sand mining in the Bay, the Commission, which includes among its members Lieutenant Governor Gavin Newsom, failed to rely on the best available science. Erosion is already a serious problem at Ocean Beach. Removing significantly more sand could threaten the Great Highway, cause a major city sewer line to rupture, and wash away sensitive habitat for shorebirds.
Among the recent scientific findings:
- The coast just south of the Golden Gate is eroding more rapidly than any other California coastal area. Since the 1980s, erosion has accelerated by 50% from Ocean Beach to Point San Pedro. This coincides with unsustainable sand mining from the Bay’s floor.
- Each year, more sand is lost due to mining and dredging of San Francisco Bay than the amount that washes into the Bay from upstream.
- The two major sand mining sites are on the Bay floor along the natural pathway for sand that washes down from the Sierras, through the Bay, and out the Golden Gate (that’s why they mine there).
- Generally, sand washing out of San Francisco Bay moves south along the coast where it should naturally replenish Ocean Beach and beaches in Pacifica and further south.
- Erosion caused by sand mining and dredging has changed the mouth of the Bay, driving more sand to the north end of Ocean Beach, and less to its south end.
Excessive sand mining not only contributes to erosion of coastal beach habitat, but also disrupts the Bay’s ecosystem by impacting bottom-dwelling invertebrates and shellfish. A major mining area is between the San Francisco waterfront and Angel Island, which is used by juvenile Dungeness crab, sturgeon, and other important Bay species.
In addition to suing the State Lands Commission to prevent excessive sand mining in the Bay, Baykeeper is also urging the Bay Conservation and Development Commission (BCDC) not to issue permits allowing excessive sand mining. Sand miners in the Bay must have both a lease from the State Lands Commission and a permit from BCDC, so the permit process provides an opportunity for a decision based on sound science that will protect the Bay and Ocean Beach. However, BCDC is under heavy pressure from sand mining companies to allow the removal of huge amounts of sand from the Bay.
Baykeeper is using the courts and pressure on regulatory agencies to stop excessive sand mining in the Bay, with the goal of preventing harm to the Bay ecosystem and erosion of Ocean Beach and beaches south of the Golden Gate.
The complete special issue of Marine Geology, A multi-discipline approach for understanding sediment transport and geomorphic evolution in an estuarine-coastal system: San Francisco Bay, edited by P.L. Barnard, B.E. Jaffe and D.H. Schoellhamer, Volume 345, Pages 1-326 (1 November 2013) with 21 articles, is available online.