Water windfall: Key California reservoir fills for just third time in 12 years

San Luis Reservoir, between Gilroy and Los Banos, is the largest off-stream reservoir in the United States

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Five months ago, San Luis Reservoir — the massive lake along Highway 152 between Gilroy and Los Banos — was just 24% full, an arid landscape of cracked mud and lonely boat ramps painfully far away from the dwindling water’s edge.

But today in one of the most visible signs that Northern California’s drought is over, San Luis is full. Since Nov. 8, the water level has risen 144 feet — roughly the equivalent of submerging a 10-story building.

The state’s fifth-largest reservoir, a key water supply for millions of people from Silicon Valley to San Diego that also irrigates hundreds of thousands of acres of Central Valley farmland, is at 98% capacity and expected to reach 100% in a few days.

“A lot of people are coming out to take photos of it,” said Arzan Kermani, a state park aide working at the lake’s south shore this week. “They’re really surprised. The happiest people are the boaters. Hopefully, it stays this way for a long time.”

Hillsides around the 9-mile-long reservoir’s shoreline have turned from parched yellow to pastoral green.

“It’s significant,” said Levi Johnson, an operations manager with the U.S. Bureau of Reclamation. “It’s a huge turnaround after three consecutive years of drought.”

The dramatic improvement is just the third time in the past 12 years that the reservoir, which was dedicated by John F. Kennedy in 1962, has been full. The bounty is part of the reason why Santa Clara County and other parts of the state have been told by state and federal water providers they will receive all the water they need this summer. Since 2012, only 2017 and 2019 saw similar conditions.

“It looks massive,” said Lars Kvarna of Mountain View, who visited for a hike on Wednesday. “And the hills are about as green as it gets. It’s impressive that the reservoir can fill up so quickly.”

The lake holds 2 million acre-feet, enough water for 10 million people for a year. A vast inland sea, it contains 12 times as much water as Los Vaqueros Reservoir in Contra Costa County, five times as much as Yosemite’s Hetch Hetchy and 100 times as much as Lexington Reservoir in Los Gatos.

Unlike many dams, which are built on big rivers, San Luis’ 382-foot-high earthen dam holds back a reservoir that acts as a switching yard for California’s water system. The reservoir is filled not by blocking a river, but by people — officials from the state Department of Water Resources and federal Bureau of Reclamation. They pump water from the Sacramento-San Joaquin River Delta near Tracy, 65 miles to the north, into San Luis, where it is stored. Then it’s sent down canals to 600,000 acres of farms in the San Joaquin Valley and cities as far south as Los Angeles and San Diego.

A tunnel from the reservoir through the Diablo Range also sends the water into Silicon Valley, where it is a key part of the water supply for the Santa Clara Valley Water District.

On Tuesday, the U.S. Bureau of Reclamation, which jointly operates San Luis Reservoir with the state Department of Water Resources, announced that cities south of the Delta will receive 100% of their water allocations through the Central Valley Project this summer — up from 25% last year and the year before. Farmers south of the Delta will receive 80%, up from 0% the past two years.

In fact, there’s so much water in California’s reservoirs and canals after a winter of atmospheric river storms, and the promise of much more when the record Sierra snowpack melts, that finding places with capacity to store it is becoming a challenge.

“It’s what happened in 2017,” said Jeffrey Mount, a professor emeritus at UC Davis and senior fellow at the Public Policy Institute of California’s water center. “They’re running out of places to put water.”

On Monday, Metropolitan Water District, which serves 20 million people in Southern California, began refilling Southern California’s largest reservoir for the first time in three years. Now 61% full, Diamond Valley reservoir in Riverside County will go to 100% this year, they said, with the same Delta water that has filled San Luis.

Last week, Gov. Gavin Newsom relaxed most water restrictions in California.

“Are we out of the drought?” Newsom said. “Mostly. But not completely.”

He noted that some parts of the state, particularly the Central Valley where farmers have overpumped groundwater for generations, still have overdrawn aquifers.

In March, Newsom signed an executive order to reduce red tape through June 1 to allow more water — particularly as the Sierra snowmelt — to be stored in underground aquifer recharging projects. Newsom has come under some criticism, however, for not constructing any new reservoirs during his more than four years in office.

The construction of San Luis is part of California’s water lore.

On Aug. 18, 1962, President Kennedy, in a well-tailored blue suit, after flying to California on Air Force One, took a helicopter to the construction site. He was met by Gov. Pat Brown, former Gov. Jerry Brown’s father, and a crowd of local officials, farmers and others.

It was a time when the elder Brown was pouring concrete across the state, building highways, universities, dams and other structures.

“It is a pleasure for me to come out here and help blow up this valley in the name of progress,” Kennedy joked.

Click here to read the full article in the Mercury News


  1. Richard Cathcart says

    Earthquake-producing nearby fault could rupture the dam. Release of the reservoir’s waters could flood an important part of Stockton, amongst other places. Tunneling through the fault to expand the Bay Area’s rapid-transit railway might destabilize the fault. The dam has been repaired during recent years but will the repairs be adequate since the fiasco at Oroville Dam’s poor-quality spillway engineering has become known? But, very likely, our State’s “leadership” will put all these postulations to the very rear of their oh-so unproductive minds.

  2. Overconfidence about future water supply has spread like a cancer through California. Given all of the land subsidence in the Central and San Joaquin Valleys through the most recent drought, consideration needs to be given toward creating a large number of injection wells to handle the excess water now and what will be created when the snow melts if there is no place to store it for future demand. Replenishing aquifers should be a top priority when government officials aren’t busy with political correctness.

  3. Mary Cunningham says

    Where are the new dams the voters approved years ago

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