Fresno drivers headed to the Bay Area via Pacheco Pass on Highway 152 can’t help but take note of a sprawling inland sea that seemingly appears out of nowhere among the yellowed, oak-dotted foothills.

This is San Luis Reservoir, essentially a 2 million acre-foot holding tank built to irrigate San Joaquin Valley farms and supply drinking water to Silicon Valley. Its construction was considered such a significant addition to California’s water supply that President John F. Kennedy turned out in 1962 to push the dynamite plunger.

“It is a pleasure for me to come out here and help blow up this Valley,” Kennedy quipped from a temporary grandstand erected atop a nearby hill.

Six decades later, the 3½-mile long earth dam that towers above 152 and impounds the federally owned, state operated reservoir is getting fortified. Construction crews are 2½ years into a $1.1 billion seismic upgrade of B.F. Sisk Dam that won’t be completed until 2031.

Opinion

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Funded mainly by the 1978 Safety of Dams Act, the project will raise the 382-foot-tall dam by 10 feet and add additional safety features designed to ease concerns of widespread flooding if slumping were to occur during a major earthquake. (San Luis Reservoir lies within two fault zones and is situated uphill from the nearby communities of Los Banos and Santa Nella.)

So far, the 120 to 150 workers have focused on reinforcing and raising three different stability berms along the dam’s midsection where seepage had been occurring. Most of the material required, millions of cubic yards worth of boulders, riprap and gravel, is excavated from an on-site quarry and transported to the dam via a steady procession of dump trucks operating 12 hours a day.

Just by itself, the Sisk Dam safety modification project does not increase the reservoir’s capacity. To accomplish that, the Bureau of Reclamation and San Luis & Delta-Mendota Water Authority are teaming on a second 10-foot dam raise that would create an additional 130,000 acre feet of storage.

Enlarging the reservoir is projected to cost an additional $1 billion. But because the 10-foot storage raise would take place concurrently with the 10-foot seismic raise, work that isn’t scheduled to begin until 2027, the partners have time to assemble a funding plan. The next public negotiations are Aug. 22-23 in Monterey.

“We want to maximize the effort and minimize the expense,” said Henry Garcia, the Bureau of Reclamation’s construction manager.

Little scrutiny, zero opposition

The expansion of San Luis Reservoir is a small part of a larger effort by the state and federal agencies to increase water storage. But unlike virtually every other dam project in California, this one was approved with little public scrutiny and zero opposition from environmentalists — even though the extra 130,000 acre feet of water would come out of the heavily scrutinized San Joaquin-Sacramento River Delta.

Why is that?

As with everything involving water and the environment in California, there are multiple factors at play.

The first of those is overload. Ron Stork, policy director at Friends of the River, rattled off more than a half-dozen dam projects his Sacramento-based environmental group and others are rallying against. They include: Sites Reservoir, a 1.5 million acre-foot offstream storage site planned in Colusa County; the proposed 25-fold expansion of Pacheco Reservoir, just over the hill from San Luis and connected to it via a tunnel that runs through Pacheco Pass; and most urgently of all, the Trump-administration plan to raise Shasta Dam, which would inundate protected salmon habitat on the McCloud River.

With all that going on — in addition to the ongoing battle against the Delta tunnel — environmentalists are compelled to prioritize their efforts. And San Luis, a vital cog in the state’s conveyance system already in operation, ranks at the bottom.

“Those other projects are taking out beautiful portions of God’s green earth where San Luis Reservoir would essentially extend the bathtub ring around an existing 2 million acre-foot reservoir,” Stork said.

“So, yeah, that’s not so good. But if you’re up to your neck in alligators, some alligators are more important than others.”

‘The least worst thing’

Osha Meserve, an environmental lawyer who is among the coalition opposed to the expansion of Pacheco Reservoir by the Santa Clara Valley Water District, which receives drinking water from San Luis Reservoir, called the San Luis dam raise “the least worst thing” among all the storage projects currently planned in California.

“There’s so many destructive water infrastructure projects being proposed right now that I think people are having to prioritize the ones that they believe are the most damaging to the environment and are the worst investments of public funds,” Meserve said.

San Luis Reservoir doesn’t rise to that level, Meserve added, because one can argue the worst environmental damage occurred during its original construction. Also, the federal government is largely footing the bill.

The fact that the 10-foot capacity raise and the 10-foot seismic raise were submitted as individual projects has also added to the general confusion. Despite that, mitigation measures included in the Sisk Dam Raise and Reservoir Expansion Project essentially mirror those submitted for the seismic work. On top of that, the public comment period occurred in August 2020 during the height of the pandemic.

Only four letters not written by government agencies or water districts are included in the final Environmental Impact Report. Three were submitted from local farmers in support of more storage.

“They did it in pieces so you can’t see the entire project, and they did that at a time when public input was spotty,” said Patricia Schifferle, director of the water consulting firm Pacific Advocates. “It was designed to make sure the public doesn’t comment. That was the intentional process.”

Construction on the earth dam that contains the largest offstream reservoir in the United States will continue another seven years, at least. After which it’ll be structurally safer and 6.5% larger.