Walker Creek Mercury TMDL

Walker Creek, located in Western Marin County, California, is a 21-kilometer stream that flows through a former mercury mining district into Tomales Bay. The Walker Creek watershed supports steelhead and coho salmon, a diverse array of wildlife, and recreational fishing in Soulejule Reservoir. Mercury-laden sediment originating from inactive mercury mine sites threatens wildlife such as fish-eating birds, and also humans who consume fish from the reservoir.

The TMDL for mercury in the watershed includes a broad-based implementation strategy for reducing both mercury discharges and methylmercury production. In recent years, the Water Board and U.S. EPA collaborated in highly successful cleanup efforts at the Gambonini Mine site (the greatest source of mercury in the watershed). Reductions already achieved in the amount of mercury coming off the mine site indicate that when parties in the watershed work together, water quality in Walker Creek will once again support a healthy fishery and the wildlife that depend upon it.