Water Supply

All of Hillsborough’s water is provided by the San Francisco Public Utilities Commission (SFPUC). The SFPUC water supply comes from three major sources: Hetch Hetchy Reservoir in the Sierra Nevada Mountains, and the local watersheds in Alameda County and the Peninsula. Some customers occasionally notice slight changes in the flavor and hardness of their water as the ratio of waters from these sources changes according to seasonal and climate changes throughout the year. These changes are normal and pose no adverse health effects.

Hetch Hetchy Reservoir

Hetch Hetchy Reservoir


The Hetch Hetchy Reservoir, the largest reservoir in the SFPUC system, is located in Yosemite National Park. It provides approximately 85% of the total water supply. This high quality water supply meets all federal and state criteria for watershed protection, disinfection treatment, bacteriological quality, and operational standards. As a result, the Environmental Protection Agency and California Department of Health Services granted the Hetch Hetchy water source a filtration exemption. This exemption is contingent upon the Hetch Hetchy source continuing to meet all filtration avoidance criteria.

Alameda County & Peninsula Watersheds


Alameda County and Peninsula watersheds produce about 15% of the total SFPUC water supply. The Alameda watershed, located in Alameda and Santa Clara counties, collects local runoff and stores the water at Calaveras and San Antonio reservoirs, supplemented by groundwater from Sunol Filter Galleries. All water from these sources is treated at the Sunol Valley Water Treatment Plant located in the East Bay. Runoff captured in the Peninsula watershed in San Mateo County is stored in four reservoirs located just to the west of Interstate 280. This water source is treated at the nearby Harry Tracy Water Treatment Plant.

Crystal Springs Reservoir

Protecting Water Resources


The SFPUC aggressively protects the natural water resources entrusted to its care by continuously monitoring its watersheds' weather conditions, water turbidity levels, and microbial contaminants. The annual update of the Watershed Control Program and Sanitary Survey describes the Hetch Hetchy watershed and water supply system, identifies potential sources of contamination in the watershed, discusses the existing and recommended watershed management practices that protect water quality, and summarizes the water quality monitoring conducted last year. The SFPUC also conducts a sanitary survey of local watersheds every 5 years. These surveys have consistently found very low levels of contaminants, and water from the Hetch Hetchy Reservoir continues to remain safe and clean.

Bay Area Water Supply & Conservation Agency


The Town of Hillsborough is also a member of the Bay Area Water Supply and Conservation Agency (BAWSCA). BAWSCA is working with the San Francisco Public Utilities Commission to implement the $2.9 billion capital improvement program. In particular, BAWSCA wants to ensure the aging water system is fixed and upgraded to withstand the seismic events expected to occur on the earthquake faults that cross under the system.

Urban Water Management Plan


The Urban Water Management Plan Act (California Water Code §10610-10656) requires the Town of Hillsborough to update its Urban Water Management Plan (UWMP) every 5 years. The UWMP evaluates Hillsborough's water supply and demand and provides a blueprint for meeting the community's long-term water supply objectives. The Town updated its 2010 UWMP after proposed revisions were made available for public review. A public hearing was held July 11, 2016 and the 2015 UWMP (along with attachments) was adopted by the City Council. The adopted UWMP has been submitted to the Department of Water Resources, and a printed copy was made available at Town Hall for public review for 30 days after adoption.

Urban Water Management Plan
Water Shortage Contingency Plan