Hetch Hetchy Water System

The cities, water districts and private utilities represented by the Bay Area Water Supply and Conservation Agency (BAWSCA) rely upon the Hetch Hetchy system for water to protect the health, safety and economic well being of 1.7 million citizens, businesses and community organizations. Together, the BAWSCA agencies account for two-thirds of water consumption from the system and pay for two-thirds of its upkeep. The BAWSCA agencies are therefore key stakeholders in ensuring the system serves as a reliable source of high quality water.

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While constructed and owned by San Francisco, the water system was in fact planned to benefit the greater San Francisco Bay Area population. Several cities and water agencies that are now part of BAWSCA urged Congress to pass the Raker Act in 1913, the law that allowed federal lands in the Sierra Nevada Mountains, including Hetch Hetchy Valley in Yosemite National Park, to be used to build the water system. The cities of Burlingame, Hayward, Menlo Park, Palo Alto, Redwood City and San Mateo, along with the Alameda County Water District, were among Bay Area communities whose support was influential in persuading Congress to pass the controversial Act, and President Woodrow Wilson to sign it.

Construction of the regional water system proceeded over the following 20 years, with water first delivered in 1934. As the system aged, especially in an era of heightened safety awareness following the Loma Prieta Earthquake in 1989 and drought in the 1990s, it became evident that the system required a complete overhaul. BAWSCA agencies advocated for the capital improvement program that was adopted by the SFPUC in 2002, and are actively monitoring its implementation. BAWSCA agencies also are implementing water conservation and water recycling projects to help preserve this precious resource for their communities, and are working to identify alternate sources of water supply.

The regional water system provides water to 2.4 million people in San Francisco, Santa Clara, Alameda and San Mateo counties. Eighty-five percent of the water comes from Sierra Nevada snowmelt stored in the Hetch Hetchy reservoir situated on the Tuolumne River in Yosemite National Park. Hetch Hetchy water travels 160 miles via gravity from Yosemite to the San Francisco Bay Area. The remaining 15 percent of water comes from runoff in the Alameda and Peninsula watersheds. This local water is captured in reservoirs located in San Mateo and Alameda counties. Delivering approximately 260 million gallons of water per day, the regional system consists of over 280 miles of pipelines, over 60 miles of tunnels, 11 reservoirs, five pump stations and two water treatment plants.

Find out more about the system at http://www.sfwater.org
Click here to view a virtual tour of the Hetch Hetchy Watershed.

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