San Luis Reservoir, just west of the San Joaquin Valley town of Los Banos, is California's sixth-largest reservoir and stores water pumped south from the Delta by the federal Central Valley Project and State Water Project. February 2015. (Dan Brekke/KQED)
One of the Bay Area’s largest reservoirs is about to get bigger, thanks to a partnership between local water agencies and the federal government.
The San Luis Reservoir Dam, between Los Banos and Gilroy, will be raised 10 feet to collect an additional 130,000 acre-feet of water per year. The addition will be enough to serve roughly 650,000 people annually, helping California better prepare for more extreme weather patterns due to climate change.
“California is seeing more severe droughts,” Paul Rogers, an environmental reporter with The Mercury News, told KQED.
But the state is also having wetter years when storms do hit.
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“Experts say California needs to build more reservoirs to store water in those rare wet years to reduce shortages during the inevitable droughts,” Rogers said. “This is about increasing California’s ability to store more water. In other words, put more in the bank for those dry years.”
The U.S. Bureau of Reclamation and water agencies in the East Bay, South Bay and San Joaquin Valley agreed to the nearly $1 billion project that will add 130,000 acre-feet to Northern California’s water reserve.
Low water levels at San Luis Reservoir on Feb. 13, 2014. (Josh Cassidy/KQED)
Under the current agreement, the federal government will contribute 30% of the funding to raise the San Luis Dam and will receive that same percentage of the water. Santa Clara County will absorb about half the cost — $435 million — and add 60,000 acre-feet of water, while seven other Northern California water agencies will add smaller amounts.
For Santa Clara, this would reduce the water shortage in a six-year drought period by about 66%, according to the county’s water district. It said the project could also enhance others the county is pursuing, like banking groundwater and a proposed delta conveyance project that would bring water from the Sacramento River to the country underground.
It comes as the region, which depends on a large agriculture industry, is facing increased risks associated with drought. Since 1985, California has gotten drier, according to its Office of Environmental Health Hazard Assessment. Between 2012 and 2016, it experienced its most severe drought to date. Since then, there have been only a few rainy seasons.
The U.S. Bureau of Reclamation built the San Luis Reservoir, already the fifth largest in California, in the 1960s. It serves as an irrigation source for farms across the Central Valley and drinking water in San José and other areas of the South Bay.
Construction will be concurrent with a $1.1 billion federal project to retrofit the dam and add another 10 feet in height to reduce risks during seismic events. The projects will require rerouting about a mile of Route 152, which connects Highway 1 along the coast and Highway 99 to the east. Construction is set to begin in 2028.
But before then, a lot could change. Santa Clara’s Board of Supervisors will have to approve funding, the project will need to get proper permits, and all eight districts will need to agree to form a legal authority.
The Department of the Interior will hold a ceremony on Wednesday to mark the agreement, and then the eight water districts will parse through the fine print.
“They have to do the design, the planning, they have to work on the financing. But these principles basically show which agencies are in, how much they would pay and how much water they would get,” Rogers said. “Now, they’ll work on those details for the next couple of years.”
