Water Supply & System

Water Supply


The cities, water districts and private utilities represented by the Bay Area Water Supply and Conservation Agency (BAWSCA) rely upon the San Francisco Regional Water System system for water to protect the health, safety and economic well being of 1.8 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 regional water system provides water to 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. 




• SFPUC State of the Regional Water System Report - November 2022

SFPUC Water Supply Availability Estimate - April 15, 2021

• BAWSCA Long-Term Reliable Water Supply Strategy - January 2015


WSIP Draft Program Environmental Impact Report (PEIR)

BAWSCA’s Comments


Revenue Bond Oversight Committee (RBOC)

Financial Review of Aspects of the WSIP – Dated Sept. 21, 2007

Review of WSIP Expenditures Under PUC’s Commercial Paper Program – Dated July 17, 2006