The Hetch Hetchy watershed, an area located in Yosemite National Park, provides approximately 85% of San Francisco's total water needs. Spring snowmelt runs down the Tuolumne River and fills Hetch Hetchy, the largest reservoir in the SFPUC system. This surface water in the Hetch Hetchy Reservoir is treated, but not filtered because it is of such high quality.
The Alameda and Peninsula Sources
Together the Alameda and Peninsula watersheds produce about 15% of the total water supply. The Alameda watershed, located in Alameda and Santa Clara Counties, contributes surface water supplies captured and stored in two reservoirs: Calaveras and San Antonio. The Sunol Filter Galleries located near the Town of Sunol, are a groundwater source supplying less than one percent of San Francisco's water. The Peninsula watershed in San Mateo County contributes surface water supplies captured and stored in lower and upper Crystal Springs and San Andreas Reservoirs and in two smaller reservoirs, Pilarcitos and Stone Dam. The 6 reservoirs in the Alameda and Peninsula watersheds capture rain and local runoff. Some also store Hetch Hetchy water for use by San Francisco. These local water sources and groundwater from the Sunol filter galleries are treated and filtered before delivery.
Join the SFPUC and other members of the Pilarcitos Creek Restoration Work Group for the first of three public workshops to develop an integrated watershed management plan for the Pilarcitos Creek Watershed. Read more
