$10 million temporary Delta rock barrier to keep salty water away from critical pumps is 800 feet long
In a new symbol of California’s worsening drought, construction crews are putting the finishing touches on a $10 million emergency project to build a massive rock barrier through part of the Delta in Contra Costa County to preserve water supplies for millions of people across the state.
The 800-foot long barrier — the size of San Francisco’s Transamerica Pyramid laid on its side — is essentially a rock wall, 120 feet wide, built in water 35 feet deep.
Its purpose: To block salt water from the Pacific Ocean and San Francisco Bay from flowing too far east and contaminating the huge state and federal pumps near Tracy that send fresh water south to 27 million people — from San Jose to Los Angeles — and to millions of acres of farmland in the Central Valley and beyond.
In a worst-case scenario, if too much salty water reached the pumps, they might have to be shut down.
“It would be a real bad situation,” said Jacob McQuirk, a principal engineer for the state Department of Water Resources who is leading the barrier project. “Water would be too salty for irrigation. Municipal supplies wouldn’t be able to draw from the Delta. Once you lose control, the only way to get it back is through big winter storms. And we don’t know when those are coming.”
The Delta, a vast system of sloughs, creeks, channels and islands roughly the size of Yosemite National Park, is located between Stockton and San Francisco Bay, where the state’s two largest rivers, the Sacramento and the San Joaquin, meet. It is one of the linchpins of California’s water supply.
What’s happening now is like an aquatic rugby scrum. Two enormous forces, the ocean and the state’s rivers, are pushing at each other with immense power. And state water officials are trying to help the fresh water side win or at least keep from being totally overrun.
Following the two driest winters since 1976-77, Gov. Gavin Newsom on April 21 signed an executive order directing the state to take various steps to deal with drought conditions. Among them was construction of the emergency barrier. The state put the job out to bid. The winning bidder, Kiewit Corporation, is a privately held construction company based in Omaha, Nebraska.
Kiewit also oversaw the $1 billion job to rebuild the spillway at Oroville Dam in Butte County after it collapsed in massive storms in 2017.
Crews are working seven days a week, 24 hours a day, adding 8,000 tons of rock to the barrier each day. Work began June 3 and is expected to finish this week. Under the emergency contract, Kiewit will be awarded $80,000 for every day it completes the work before July 1.
Workers are moving roughly 90,000 cubic yards of rock — enough to fill 9,000 dump trucks — from a loading facility about 20 miles away near the Port of Stockton. The rocks are being shipped on barges to the construction site, about 3 miles north of Oakley, between Jersey Island and Bradford Island, in the Delta. There they are being laid across the channel with excavators and other heavy equipment.
They will be removed no later than Nov. 30 when the winter rainy season traditionally begins, state officials say.
A similar emergency rock barrier was constructed in the same location during California’s last drought in 2015. It cost $30 million. Then there was only one bidder, instead of four this time. And the company used steel sheet piles and had to purchase new rocks, instead of using boulders the state had on hand, as is happening now. Scientific studies afterward found that barrier worked and kept salinity levels from spiking in the inner Delta.
But it wasn’t without controversy. The barrier blocks boaters and fishermen from a popular route. Researchers also found it increased invasive weeds and clams in Frank’s Tract, a nearby Delta location. Some property owners in the area said it increased erosion.
One of the benefits, McQuirk said, is that the barrier allows more fresh water to be kept in big reservoirs across Northern California, such as Shasta and Oroville, because not as much has to be released to keep the salt water at bay. The drought may end this winter with heavy rains. Or it could go on for three, five or 10 years more, making every gallon saved now more valuable in the future.
“We don’t know when the reservoirs are going to fill again,” he said. “We really don’t know. What we are doing is preserving water for beneficial uses later.”
Most environmentalists say they accept the need for the barrier. But they worry about the impact on fish, such as endangered smelt and salmon, and the risk of huge algae blooms in the area. More broadly, they say the state Department of Water Resources and federal Bureau of Reclamation let too much water out of big reservoirs last fall and this spring for farmers in the Central Valley, even after they knew the drought was worsening.
“They do not have the backbone to say no to the big agriculture producers, especially during a recall election,” said Barbara Barrigan-Parrilla, executive director of Restore the Delta, an environmental group in Stockton. “But even without a recall, they cannot come to terms with the fact that we have promised far more water through water rights than exists in the system. And climate change is making it worse.”
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