About This Project

Non-interactive picture of the reservoir The Bureau of Reclamation, the California Department of Water Resources (DWR) and Contra Costa Water District (CCWD) have partnered in studies that culminated in CCWD expanding their Los Vaqueros (LV) Reservoir from 100,000 acre-feet to 160,000 acre-feet. When CCWD decided to expand the reservoir without federal funding, Reclamation determined that a final feasibility report was not required but participated as the NEPA lead for the Final Environmental Impact Statement/Environmental Impact Report (EIS/EIR), completed in 2010. Phase 2 is a continuation of the feasibility study for a potential second reservoir expansion to a total capacity of 275,000 acre-feet. The 2010 EIS/EIR included assessment of a 275,000 acre-feet expansion alternative with a pipeline connection from the reservoir to the South Bay Aqueduct (the Transfer-Bethany Pipeline) which could result in regional and indirect statewide benefits.


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 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, important terrestrial habitat in the watershed, operations flexibility to the Central Valley Project to varying degrees, and incremental Level 4 water supplies to South-of-Delta wildlife refuges.

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.

Reclamation, DWR, and CCWD partnered in studies that culminated in 2009 with CCWD deciding to expand their LV Reservoir from 100,000 acre-feet to 160,000 acre-feet without federal funding. Reclamation determined that a feasibility report was not required at that time and put the feasibility study on hold from 2010 to 2015. A final environmental document was completed in 2010, and it included assessment of 160,000 acre-feet to 275,000 acre-feet expansion alternatives. Currently, the renewed feasibility study is focused on potential federal investment in alternatives to increase reservoir capacity to 275,000 acre-feet, as well as constructing various conveyance and pumping facilities.

Primary objectives of the Los Vaqueros Expansion are:

  • Increase reliability of Delta water supplies for water providers within the Bay Area to help meet M&I water demands during drought periods and emergencies.
  • Develop water supplies for environmental water management that supports fish protection, habitat management, and other environmental water needs.

Secondary objective of the Los Vaqueros Expansion is:

  • Improve the quality of water delivered by Bay Area water providers without impeding primary objectives.
Documents supporting the project are available online on the Contra Costa Water District site or at the CCWD's Los Vaqueros Studies site.


Lisa Rainger
Project Manager
Phone: (916) 978-5090

Lisa Navarro
Public Affairs Specialist
Phone: (916) 978-5111
Last Updated: 7/3/17