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Expanded reservoir wins regional backing

Issue Date: June 28, 2017
By Christine Souza
Grassland Water District general manager Ric Ortega and farmer Bill Diedrich discuss the future of water at a wildlife refuge near Los Banos. As Central Valley Project water contractors, Ortega and Diedrich say they both stand to benefit from the proposed expansion of Los Vaqueros Reservoir, an existing off-stream facility in the foothills east of San Francisco.
Photo/Christine Souza
The Contra Costa Water District, owner of Los Vaqueros Reservoir, says a proposed expansion would increase storage capacity by 115,000 acre-feet and add flexibility to the state’s water system.
Photo/Christine Souza

Editor's note: This is the final installment of a three-part Ag Alert® series about large-scale water storage projects applying to the California Water Commission for funding from the Proposition 1 water bond.

Additional flexibility for the water-supply system, water to benefit urban customers in the Bay Area, water for wetlands as well as for farmers and other water users south of the delta: Those are the reasons a dozen partners have joined in support of a proposed expansion of Los Vaqueros Reservoir.

The Contra Costa Water District, which has proposed the $800 million project, says it would store additional water for 500,000 customers in the district's service area. It would also hold transfer water for south-of-delta contractors, including agricultural districts and Central Valley wildlife refuges.

Long studied by the CCWD and the U.S. Bureau of Reclamation, the project is among those competing for a portion of $2.7 billion in storage funding available through the voter-approved Proposition 1 water bond. A dozen potential partners have signed a memorandum of understanding supporting the project, according to Marguerite Patil, CCWD special assistant to the general manager.

"The best project for this site is a regional project, and when you have a broader, more regional project you diversify your risk," Patil said. "It's not big enough to solve everybody's problems at every time, but it is about managing different demands in different year types."

Proponents of the Los Vaqueros expansion and other projects have until mid-August to finalize applications for bond funds. If awarded, bond money would be used toward public benefits of the projects, such as ecosystem, fishery and water quality improvements; flood control; emergency response; and recreation.

Situated in the foothills southwest of the Sacramento-San Joaquin Delta in Contra Costa County, the existing Los Vaqueros Reservoir is an off-stream reservoir built in the 1990s, to secure additional storage to improve water quality and for emergency storage in case of an earthquake or levee failure. CCWD, which owns the reservoir, expanded it by 60,000 acre-feet in 2012, bringing total capacity to 160,000 acre-feet. The additional expansion would increase reservoir capacity by 115,000 acre-feet, creating a total storage capacity of 275,000 acre-feet.

CCWD supplies treated drinking water to urban homes and businesses with water drawn primarily from the delta under a contract with the federal Central Valley Project. Through the proposed expansion of Los Vaqueros and addition of a new pipeline, the district said it would have the operational flexibility to store and transfer water to south-of-delta contractors.

"The Transfer-Bethany Pipeline is what everyone loves," Patil said. "It ties the hub of our system directly into the California Aqueduct. There are many different combinations for how water could move, and a good thing is, a lot of this infrastructure already exists. You don't have to go through the export pumps, so water can serve the Bay Area or it can go down the California Aqueduct and intertie with the Delta-Mendota Canal and intertie with the wildlife refuges and can go into San Luis Reservoir."

Bill Diedrich, who farms in Fresno and Merced counties and chairs the San Luis Water District board, which is a member of the San Luis & Delta-Mendota Water Authority, said, "What is meaningful about the Los Vaqueros expansion is the additional storage and the additional intake."

Diedrich, who had a zero water allocation from the CVP during recent drought years, noted that "the regulatory components of moving water south of the delta exacerbated the drought exponentially."

"The idea of being able to store water in Los Vaqueros and then, with the planned additional infrastructure, to move that water south without going through (the state or federal pumping plants) is attractive to us," he said.

Frances Mizuno, San Luis & Delta-Mendota Water Authority assistant executive director, said the Los Vaqueros expansion would provide additional operational flexibility to convey directly to and/or store supplemental supplies, such as north-of-delta transfer water or surplus CVP supplies.

"The Bethany-Transfer Pipeline will provide the opportunity for a direct delivery of water utilizing Contra Costa Water District's facilities when Jones Pumping Plant pumping is either curtailed or at maximum capacity," Mizuno said.

CCWD has conducted a number of pilot projects to move and transfer water, including one last month in which the Westlands Water District rents space in the reservoir to store 5,000 acre-feet of water. Patil called the pilot project "something that we have never done before where we are working with a CVP customer, trying to move their water into Los Vaqueros and store it for them."

Among the project's environmental benefits, the Los Vaqueros expansion would provide water to south-of-delta wildlife refuges, including in the Grassland Water District, a refuge federal contractor near Los Banos. Wetlands served by the district are habitat for waterfowl and other species along the Pacific Flyway.

Grassland Water District general manager Ric Ortega said the Los Vaqueros expansion could provide water supplies to south-of-delta refuges ranging from 30,000 to 70,000 acre-feet a year. Grassland Water District shares water with state and federal agencies, which own and manage about a third of the local refuge habitat.

Ortega said the refuge federal contractor received only about 50 percent of its normal supply and 30 percent of its contract water during the drought.

"We were shorted beyond our contractual provisions and what that means, just like in agriculture, is we have to fallow," Ortega said, reducing available habitat for the same population of birds.

Diedrich said California water managers have become increasingly resourceful in moving water as water contracts have become more unreliable.

"We need options, we need more pieces that we can use to manipulate our water supply to maximize it for the state's economy," he said. "We need an integrated system where the components work together."

This week, the CCWD is expected to release the draft supplemental document to a final environmental study on the Los Vaqueros expansion, and to schedule a series of public meetings. More information is available at

(Christine Souza is an assistant editor of Ag Alert. She may be contacted at

Online extra: Questions and answers about Los Vaqueros

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.

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