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About the Los Vaqueros Reservoir Expansion Project

Non-interactive picture of the reservoirOn March 31, 2011, a Record of Decision was signed for the Los Vaqueros Reservoir Expansion Project.  The Project includes an expansion from 100,000 acre-feet to 160,000 acre-feet, an increase of 60 percent, by raising the dam 34 feet in height to 521 feet.  Contra Costa Water District (CCWD) has completed the design and construction of the 60,000 acre-feet expansion and has developed new alternatives to consider in a feasibility study of a larger expansion of the dam and reservoir beyond the 160,000 acre-feet facilities.  CCWD is locally funding 100% of the construction costs to expand the reservoir. An alternative reservoir expansion to a capacity of 275 TAF is under reformulation. This reformulation of alternatives has resulted in a new iteration of the feasibility study. There has also been some consideration of a possible alternative expansion up to 500 TAF but no determination has been made to include it in the feasibility study.  The objectives, problems, needs, and opportunities for reformulation are being revised to address current and future unmet water supply demands in the San Francisco Bay Area. There is a local project being studied that would develop new regional desalination facilities that may be operated in conjunction with LV Reservoir storage.


The Sacramento-San Joaquin Delta (Delta) supplies water to more than twenty-three million water users in California.  At the same time, the Delta provides essential habitat for a diverse array of fish and wildlife.  There are many challenges in maintaining a balance between water use and the environmental including ecosystem restoration, water quality, and water supply reliability.

Los Vaqueros Reservoir was completed in 1997 to provide 100,000 acre-feet of water storage to improve water quality, reliability of Bay Area drinking water supplies and ecosystem restoration.  The reservoir allows Contra Costa Water District (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 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.  Lastly, the project provides recreation opportunities, flood control benefits, and important terrestrial habitat in the watershed.

CCWD is the owner and operator of the existing Los Vaqueros Reservoir, the intakes and pump stations at Old River and Middle River in the Delta, and the transfer station and pipelines to both the reservoir and the Contra Costa Canal.  Water is pumped into the reservoir from the Delta during high water flows, when water is generally low in salts and other contaminants and when impact to Delta fisheries is low.  CCWD then blends water from the reservoir with the Delta supplies during periods of lower quality. 

Los Vaqueros Expansion is one of the potential surface storage projects identified in the CALFED Bay-Delta Program Record of Decision (2000), a 30-year program signed by 18 state and federal agencies that focuses on four major resource management objectives including ecosystem restoration, water supply reliability, water quality, and levee system integrity.  The ongoing Los Vaqueros Expansion Feasibility Study is a joint undertaking among Reclamation, CCWD and the California Department of Water Resources authorized by Public Law 108-7, the Omnibus Appropriations Act of 2003. The feasibility study was initiated in September 2003 and affirmed in the CALFED Bay-Delta Authorization Act (P.L. 108-361) in 2004. 

The initial studies focused on determining if an expanded reservoir could meet state and federal program goals and the CCWD Board Principles.  Because the existing Los Vaqueros Reservoir was financed entirely by CCWD customers, one of the Board Principles required any proposed expansion be placed before CCWD voters before proceeding with the permitting and approval process. In March 2004, CCWD customers voted in favor of the expansion and authorized the project to move forward.

Primary objectives of the Los Vaqueros Expansion are:

Secondary objective of the Los Vaqueros Expansion is:

Documents supporting the project are available online at the on the Contra Costa Water District site or on a reservoir study site.

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Reclamation Project Manager
Brooke Miller-Levy Program Manager
Phone: 916-978-5296
Fax: (916) 978-5094


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Bureau of Reclamation, Mid-Pacific Region
2800 Cottage Way, Sacramento CA  95825-1898
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June 29, 2010

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