The 98-square-mile area designated as the Lower Peninsula Watersheds consists of the San Francisquito Creek, Stevens Creek, Permanente Creek, Adobe Creek, Barron Creek, and Matadero Creek watersheds, which feed the tidal wetlands along the San Francisco Bay’s southwest shoreline.
This area encompasses a fair amount of open space and public parkland, especially at higher elevations, and several streams support steelhead trout. In addition, the tidal reaches of many of the creeks in the Lower Peninsula Watersheds support the state and federally endangered Ridgway’s rail and salt marsh harvest mouse.
For the most part, Los Trancos Creek and the portion of San Francisquito Creek downstream of the Los Trancos Creek confluence mark the northwestern boundary between Santa Clara and San Mateo counties.
Stevens Creek Reservoir is the only District reservoir in the Lower Peninsula watersheds. Stanford University owns Searsville Dam on San Francisquito Creek in San Mateo County, as well as Felt Lake, an off-channel reservoir on Los Trancos Creek in Santa Clara County. Permanente Diversion Channel, constructed in 1959, transfers the majority of flows from upper Permanente Creek to Stevens Creek.