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Is California Ready to Build Its Next Big Dam?

The state hasn’t had a new large dam since 1979, but that may change with the pressures of the drought and the passage of the 2014 water bond dedicating money to new water storage projects. Five options for new or enlarged reservoirs are being considered, but one may have a better chance than others.

Written by Tara Lohan Published on Read time Approx. 5 minutes

Historically speaking, when the going gets tough, California builds more dams. “If you look at the history of California since the 1930s, every time there has been a drought people have been interested in expanding surface storage,” said Jay R. Lund, a professor of civil and environmental engineering at the University of California, Davis.

When it comes to water, things have been pretty tough in California for the past four years. So bad, in fact, that in 2014 California voters passed Proposition 1, a bond to funnel $7.5 billion to water projects, including $2.7 billion that would go to the California Water Commission to dole out specifically for storage-related projects.

During the 20th century “storage” was virtually synonymous with dams. The construction of big dams is what shaped the West, California especially. Dams gave us water and power and propelled development. We later learned they also gave us spoiled rivers, silted reservoirs and devastated fisheries. For decades, it was a trade-off we were willing to make.

O’Shaughnessy Dam, which flooded a valley John Muir called “one of nature’s rarest and most precious mountain temples,” allows San Franciscans to drink from the arms of Yosemite. Hoover Dam, the great engineering marvel, helped make possible the network of canals, pipes and pumps that bring Rocky Mountain snowmelt all the way to the lips of Angelenos.

And California’s dams, along with an intricate plumbing network, move water from wet Northern California all the way to Southern California’s populous cities and suburbs. Along the way it produces a bounty, including $54 billion a year for the state’s agricultural sector, as that water passes through the Central Valley.

Dams are undoubtedly an important part of our history. But what’s their place in our future?

“There is a group of people who will push for new surface projects no matter how wet or dry the year,” said Lund. But for a while those voices were in the background. The age of big dams appeared to be over. California’s last major reservoir project was completed in 1979 – the New Melones Dam.

Much of the most recent talk about dams in California has been about tearing them down, not building new ones. Dams are expensive, we better understand their environmental costs and most of the best spots have already been taken – there are 1,400 dams in the state.

But with the passage of the water bond, and four years of drought, California may finally be ready to write a big check for a big storage project. Or at least part of a check. State funds can only cover up to half of the total cost of proposed projects.

And there are already potential projects that have been on the drawing board for years.

Three involve expanding existing reservoirs at Shasta Lake, Los Vaqueros Reservoir and Millerton Lake. Two would involve constructing new dams – Temperance Flat on the upper San Joaquin River and Sites Reservoir north of the Delta, which would be “off-stream storage.”

A 2015 report from the Public Policy Institute of California found that “the average volume of new water from these facilities is small, and costs are high.”

Of all the proposed projects, Sites may have the best chance of being built, but it comes with a price tag of between $3.6 and $4.1 billion. The Department of Water Resources estimates that it could add up to 1.8 million acre-feet (2,220 million cubic meters) of storage and could supply 500–600 thousand acre-feet of water a year.

For any project like Sites to be built now, Lund says, it would need to be integrated with other new or existing projects.

“I think for storing large masses of water for droughts, underground storage is usually going to be better but California is a big place, a very diverse place,” said Lund. “It wouldn’t surprise me if there’s some new surface storage construction that would be useful, especially if paired with other underground storage or other kinds of operations.”

One way to do that, he said, is to operate Shasta Lake to maintain releases of cold water to help support salmon and operate Sites Reservoir for drought or normal seasonal storage needs.

Sites Reservoir has some vocal supporters. California Congressman Doug LaMalfa wrote that, “As the California Water Commission begins distributing Proposition 1 funding, it should recognize that Sites is the one project in California that meets the bond’s requirements and has virtually universal support.”

But opposition does exist. Ron Stork, senior policy analyst for Friends of the River says that his organization is skeptical of the virtues of what has been proposed so far for Sites. And others have been more direct with their criticism.

“The reservoir will remove water from the Sacramento River, drown 14,000 acres [5,500 hectares] that now contain important plant and wildlife complexes and then be operated in a way that releases warm water back into the river, effectively cooking salmon and other species,” wrote Kathryn Phillips, the director of the Sierra Club of California. A better alternative, she wrote, would be investing in groundwater storage – since “it is cost-effective, environmentally safer, climate resilient and would provide six times the storage for the money.”

Building Sites would flood the Antelope Valley, just outside the rural community of Millerton, and it would inundate a number of ranches and farms belonging to families who have been in the area for generations. The project would involve constructing two 300ft (90m) dams and nine smaller “saddle dams.” A pipeline would also need to be built that along with two existing canals, would capture water from the Sacramento River.

If the project is built, construction will be years from now. The California Water Commission won’t start issuing Proposition 1 funds to new storage projects until 2017 and that would only be part of the money needed for the project. There are still more hurdles to clear and money to be raised.

Assembly member Rudy Salas, however, is attempting to drum up support with legislation he introduced last month to expedite the process for certain storage projects.

“As California continues to combat historic drought conditions and as El Niño storms take their toll, we should be doing everything we can to update our water storage infrastructure,” said Salas. “Had these investments been made decades ago we would be prepared to capture the rainfall from recent El Niño storms. AB 1649 will make sure that California voters receive what they approved by streamlining projects that will enable us to capture more water in years of high rainfall and prevent large losses of rainwater in the future.”

Salas highlighted Temperance Flat and Sites Reservoir as two projects that already “meet statewide goals and provide public benefits to the greatest extent.”

“We’re not going to drought-proof California, no matter how much storage we build,” cautions Lund. “A lot of that [water bond] money is earmarked for environmental purposes and that is going to be a little bit hard with surface water by itself. But integrating it with non-storage re-operations and other infrastructure changes would be a promising way to go.”

A new dam, packaged with other water managements tools, could be in California’s future.

Top image: Peterson Road is the location of the proposed Sites Reservoir, near Maxwell, Calif. (Rich Pedroncelli, Associated Press)

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