California’s largest new reservoir project in 50 years gains momentum

$205 million from Congress is latest boost for Sites Reservoir. But can it overcome opposition?

Colusa County is known for sprawling rice farms and almond orchards, wetlands full of migrating ducks and geese, staunch conservative politics, and the 19th-century family cattle ranch where former Gov. Jerry Brown retired five years ago.

But the windswept county in the Sacramento Valley — whose entire population of 22,000 people is just one-third of Palo Alto’s — may soon be known for something else: The largest new reservoir anywhere in California in the past 50 years.

Last weekend, President Biden signed a package of bills that included $205 million in construction funding for Sites Reservoir, a proposed $4.5 billion project planned for the rolling ranchlands  west of the town of Maxwell, about 70 miles north of Sacramento.

The funding is the latest boost for the project, which has been discussed on and off since the 1950s. Plans call for Sites to be a vast off-stream reservoir 13 miles long, 4 miles wide and 260 feet deep that would store water diverted from the Sacramento River in wet years, for use by cities and farms around the state in dry years.

“We have a definite tailwind at our back,” said Jerry Brown, a civil engineer unrelated to the former governor, and who is executive director of the Sites Project Authority. The authority is a group of government agencies in the Sacramento Valley planning the massive reservoir.

Brown was also the former general manager of the Contra Costa Water District, where he oversaw expansion of Los Vaqueros Reservoir 15 years ago.

“The funding is a vote of confidence and a sign that the federal government sees a significant benefit to this project and it being a sound investment,” he said.

If the project overcomes opposition and a lawsuit by environmental groups, the 1.5 million-acre-foot Sites Reservoir would be California’s eighth largest. It would be four times the size of Hetch Hetchy Reservoir in Yosemite National Park, which is the main water supply for San Francisco and the Peninsula. It would provide water to 500,000 acres of Central Valley farmlands, and 24 million people, including parts of Silicon Valley, the East Bay and Los Angeles.

Plans call for groundbreaking in 2026, with construction finished by 2032. If completed, Sites would be the largest new reservoir in California since 1979, when the federal government opened New Melones Lake in the Sierra Foothills between Sonora and Angels Camp.

With the newest funding approved by Congress, the project now has more than 90% of its financing lined up, Brown said, a major hurdle that has killed dozens of other large water storage projects around the state in recent decades.

The sources include:

• A $2.2 billion loan that the U.S. Environmental Protection Agency invited the project to apply for;
• $875 million from Proposition 1, a water bond approved by voters in 2014;
• $389 million from Congress, which includes this month’s award;
• A $250 million loan from the U.S. Department of Agriculture;
• $250 million in local cash and bonds from other California water agencies;
• $60 million from Biden’s Bipartisan Infrastructure Act.

Roughly 20 water agencies from around the state have signed on as partners and would pay off the loans over decades by selling the water.

The project is supported by Gov. Gavin Newsom, farm organizations, labor unions and water agencies, including the Santa Clara Valley Water District in San Jose, Zone 7 Water Agency in Livermore, and the Metropolitan Water District in Los Angeles, all of which are partners.

Supporters say that as California’s climate continues to warm, more severe droughts are likely. Storing water in wet years to reduce shortages in dry years is more important than ever, they contend.

“We are going to need more storage projects with climate change,” said Matt Keller, a spokesman for the Santa Clara Valley Water District. “Our board is evaluating several different water supply projects from around Northern California and locally, and has been following this one for a while.”

The district, based in San Jose, provides water to 2 million people. It has contributed $2 million so far to Sites for planning and is considering offering up to $130 million more, which would provide it about 37,400 acre-feet of storage — nearly twice the volume of Lexington Reservoir near Los Gatos.

Politically, the project has a big advantage over many traditional dams. It would be an “off-stream” reservoir, which means that instead of damming a river, a remote valley of cattle ranches would be submerged, the water held in by two large dams and up to nine smaller “saddle dams” on ridges, somewhat similar to San Luis Reservoir, between Gilroy and Los Banos.

Had the reservoir already been built, Brown noted, it would have filled entirely in two years from big storms this winter and last winter.

But the Sierra Club and some of the state’s other environmental groups are opposed.

They argue that filling Sites would divert too much water away from the Sacramento River, the state’s largest, hurting endangered salmon, steelhead and Delta smelt, and depriving the Sacramento-San Joaquin River Delta of fresh water.

“It’s a costly project,” said Ron Stork, senior policy analyst for Friends of the River, a group that opposes Sites. “There’s political support for this idea — happy magical thinking that this project is going to solve our water woes in California. But it’s not the be-all and end-all for water in California.”

Stork and other opponents say cities and farms need to take less water from the Delta. Instead of new reservoirs, they argue, cities should fund water recycling projects and more conservation, and farms should embrace more drip irrigation, groundwater recharge and other techniques, and remove some unsustainable land from production.

The make-or-break moment for Sites is a series of hearings scheduled to run from June to November in which the State Water Resources Control Board will analyze fisheries studies and other documents and decide whether to award it the water rights to move forward.

In December, Friends of the River, the Center for Biological Diversity, and three other environmental groups filed a lawsuit against the project. They argued that Sites’ environmental studies, finalized in November, didn’t adequately study the reservoir’s impact on fish, or properly evaluate alternatives.

A month earlier, Newsom announced he had included Sites among the projects affected by a new state law passed last year to streamline large projects. That law, SB 149, requires that when opponents of large renewable energy, water or transportation projects sue to stop them under the California Environmental Quality Act, courts must decide the challenge within 270 days to reduce years-long delays.

“We’re cutting red tape to build more, faster,” Newsom said in November. “These are projects that will address our state’s biggest challenges.”

If Sites secures the permits, the 22 water agencies who are partners will spend 2025 negotiating how much each will pay for construction costs and how much water each will receive.

The chance of success?

“It’s 50-50,” Stork said. “There’s a lot of political faith in this project and momentum for it. I think it’s magical thinking, but it has momentum.”