Why is This Important?

Communities need potable water in adequate quantities to accommodate their residential and non-residential needs. San Mateo County has limited sources of local water, however, and relies heavily on the San Francisco Public Utilities Commission (SFPUC) to meet much of its water supply. The SFPUC system gets 85 percent of its water from Sierra Nevada snowmelt stored in the Hetch Hetchy reservoir in Yosemite National Park. The remaining 15 percent comes from local Bay Area watersheds.  With climate change expected to adversely impact Sierra snowmelt dependent watersheds like the Hetch Hetchy, growing populations in the Bay Area will increasingly compete for a decreasing amount of water.

What is a Sustainable State?

A sustainable state is one where water supplies and demand for water resources are in balance and there is a diversity of supply to reduce the risk of shortages or disruptions from any single source.

How Are We Doing?

Supply
• Water agencies (such as cities or water districts) serve nearly all San Mateo County residents and businesses. The agencies buy water wholesale from the San Francisco Public Utilities
Commission (SFPUC). In 2007-08, over 93 percent of all water consumed in San Mateo County came from SFPUC. The remaining water supply came from local sources such as groundwater and surface water. Only a very small portion (less than 1 percent) of the county's water came from recycled water, compared with the 7 percent in Santa Clara County.
• In total, water agencies in San Mateo County are allocated about 91 million gallons of water per day from SFPUC. In 2007-08, San Mateo County used 97.4 percent of its total allotment. With population growth, it is projected that by 2010-11, the county will need more SFPUC water than is available to it.
• Among local water agencies, the City of San Bruno relies least on water supplied by the SFPUC. In FY 2007-08, 48 percent of San Bruno's water supply came from local groundwater sources.
• Thirteen of the nineteen water agencies in the county rely on SFPUC for 100 percent of their water supply.

Demand
• In FY 2007-08, annual water use among the 19 water agencies in San Mateo County averaged 94.7 million gallons per day, a less than 1 percent increase from 2006-07. 2007-08 was the second year of the ongoing, three-year drought, with voluntary 10 percent water conservation programs in place throughout many local jurisdictions.
• In FY 2007-08, residential water use accounted for 67 percent of total water use, roughly the same percentage as in previous years. Commercial and industrial uses accounted for 20 percent of all water use.
• Average residential per capita consumption in the county was 89.7 gallons per capita per day (gpcpd), a slight reduction from 2006-07 when it was 91.1 gpcpd. Per capita residential water consumption decreased in 12 of the 19 jurisdictions in 2007-08.
• Residential water use is highly correlated with lot size and, by extension, income. Per capita residential water use in the county was highest in the Hillsborough (317.7 gallons per capita per day) and lowest in the Westborough Water District located in South San Francisco (48.7 gallons per capita per day).

Water Conservation Best Practices
The California Urban Water Conservation Council has compiled a list of conservation "Best Management Practices" (BMPs) for water agencies. Adoption of some or all of these 14 BMPs can result in more efficient use or conservation of water in a community. The implementation of these BMPs varies across the county's water agencies.
• Redwood City is the only jurisdiction in the county to adopt all 14 water conservation BMPs.
• Twelve agencies have adopted at least 10 of the BMPs.
• Five BMPs have over 90 percent adoption in the county.
• BMP 1 (Residential Water Surveys) and BMP 9a (Commercial Water Audits) are the least adopted BMPs, with only seven agencies having adopted each.