PUBLISHED: May 4, 2017 at 10:36 am | UPDATED: May 4, 2017 at 6:07 pm
CONCORD — The nation’s largest irrigation district will store water in the Los Vaqueros Reservoir in a test of how the lake can be used as drought insurance for millions of Californians.
The cooperative venture is between two past rivals over many Delta water issues: the Contra Costa Water District serving tap water to 500,000 people, and the Fresno-based Westlands Water District supplying irrigation water to an area with 614,700 acres on the western San Joaquin Valley.
The suppliers are partnering in a pilot project approved Wednesday by the Contra Costa Water District board.
Under the deal, Contra Costa is renting out space in its Los Vaqueros Reservoir near Brentwood for Westlands to stash enough water to cover 5,000 acres a foot deep in water. That amounts to roughly a year’s supply of water for 10,000 homes in Central Contra Costa County.
Westlands doesn’t need the water this wet year, but it could use it to irrigate crops if it faces shortages in 2018 or 2019.
Contra Costa Water managers say the project is important to demonstrate how the reservoir can be used to provide drought relief.
The deal also could help build the case for a $800 million Los Vaqueros Reservoir expansion under study as a way to store drought reserves for millions of Bay Area residents, officials said.
“You can develop all sorts of plans, but you really have to test what works, and where are the stumbling blocks you have to deal with,” said Marguerite Patil, a special assistant to CCWD’s general manager. “We haven’t tested use of the reservoir quite like this before.”
Among the many barriers, water projects can face road blocks due to concerns over impacts on threatened or endangered fish in Delta.
Under the agreement, Contra Costa Water would pump some of Westlands federal water into the reservoir this season in a time of high water flows that minimize risks of harming Delta fish.
If it needed the water in the next two years, Westlands would get it from federal pumps in the Delta. Contra Costa Water would reduce its Delta pumping by the same amount, and rely on the water stored in Los Vaqueros to make up the difference.
Patil said the project could boost Contra Costa Water’s application for up to $400 million in state bond money for a $800 million Los Vaqueros expansion to possibly serve several water suppliers. They include the Santa Clara Water District in San Jose and surrounding communities, the East Bay Municipal Utility District, the Alameda County Water Distritc, and Alameda County Zone 7 water agency in Pleasanton, Livermore and Dublin.
“It would be a concrete example of how the reservoir can be put to use,” Patil said “Water agencies are sometimes accused of doing their own thing. We’re willing to work with partners for the good of the region.”
Jonas Minton, policy advisor to the nonprofit Planning and Conservation League, said the project should be watched carefully to ensure that Los Vaqueros storage or expansion projects do not benefit agencies outside the Bay Area at the expense of Bay Area residents.
“It would seem to me that the first priority should go to other Bay Area water users,” he said. “It’s best to help your neighbors first, the ones you share a linked economy economy with.”
Contra Costa Water spokesman Jennifer Allen said her agency is committed to making sure that its customers’ water supplies and costs are not worsened by storing outsiders’ water in Los Vaqueros. Westlands will cover power costs to pump the water, and pay $300,000 to Contra Costa Water to store the water.