About the Project

The San Joaquin-Sacramento Delta provides drinking water to 23 million California residents.

Unfortunately, high salt levels and contaminants often impair water quality in the Delta. When the flow of fresh water into the Delta declines in the late summer and fall, drinking water quality degrades.

Water supplies from the Delta can also be altered or disrupted by regulatory restrictions on pumping, power outages, droughts, and emergencies. The Delta provides important habitat for many species of fish and wildlife, including several threatened and endangered fish species such as winter- and spring-run chinook salmon, steelhead, Delta smelt, and Sacramento splittail.

Delta fishery resources have declined from historical levels for a variety of reasons, including human activities such as water supply diversions, discharges into the Delta and its tributaries, and loss of habitat.

CALFED Record of Decision

The CALFED Bay-Delta Program is a consortium of state and federal agencies committed to restoring the Bay-Delta environment and improving the management of California’s most precious natural resource: water. After years of analysis and public input, the CALFED Bay-Delta Program developed a long-term comprehensive plan for restoring the Bay-Delta ecosystem and improving water supply reliability, water quality and levee integrity. This comprehensive plan is described in the CALFED Bay-Delta Program's August 2000 Programmatic Record of Decision (ROD).

Among other elements, the ROD describes the need for additional surface water storage as an important activity to improve water quality and water supply reliability. The ROD identifies five potential locations for expanding surface water storage, including the Los Vaqueros Reservoir in Contra Costa County.

The CALFED Program is currently conducting studies for four of these potential water storage projects. The other potential projects are: enlarging Shasta dam, a new Sites Reservoir (north of Delta), and new or expanded storage on the San Joaquin River (possibly enlarging Friant dam).

Existing Los Vaqueros Reservoir

The Contra Costa Water District owns and operates the existing Los Vaqueros Project in Contra Costa County to improve water quality for CCWD customers, provide stored water for emergencies, and improve the Delta habitat.

The project includes a 160,000 acre-foot reservoir, a nearly 20,000-acre watershed, Delta intakes, pipelines, and related facilities. Water is pumped into the reservoir from the Delta during high water flows, when the water is generally low in salts and other contaminants and when impacts to Delta fisheries are low. CCWD then blends water from the reservoir with Delta supplies during periods of lower quality.

The reservoir also allows CCWD to reduce impacts on aquatic Delta species at the water intakes. With the Los Vaqueros Reservoir, CCWD can reduce or eliminate seasonal water pumping when sensitive fish species are near the intakes, increase pumping during periods when fish are not present, and shift pumping between various intake locations.

The reservoir serves as an important emergency storage facility that can be used if CCWD is not able to divert water from the Delta. The Los Vaqueros Reservoir also provides recreation opportunities, flood control benefits, and important terrestrial habitat in the watershed. The Los Vaqueros Reservoir Expansion Project is examining the feasibility of expanding the benefits of the existing reservoir to help meet CALFED Program objectives and serve the water quality and water reliability needs of the Bay Area.

Los Vaqueros Reservoir History

Originally completed in 1988, capacity of the reservoir increased from its original 100,000 acre-feet to 160,000 acre-feet in 2012. The Environmental Impact Statement/Environmental Impact Report for that work included further expansion up to 275,000 acre-feet.

With environmental documentation already done, further expansion of the reservoir is ready to proceed in the near term with commitments from agency partners and funding.

See more about Los Vaqueros.

Map of the Delta