The drought has spurred California to revive controversial plans to build rock dams across three Delta waterways in an effort to prevent seawater from degrading drinking water for 25 million people — including those in San Jose, Concord, and Livermore.
The quality of state irrigation water for 750,000 acres of farms also is at risk.
Low river runoff in droughts weakens the flows that keep seawater from San Francisco Bay pushing inland and into the water pumps in the Delta, heart of California’s water system.
The state proposed the dams last year, igniting fears that wild fish and recreational boating would suffer. Environmentalists worried that salmon migrations would be disrupted.
In the end, the state concluded the drought wasn’t bad enough to warrant the dams — at least not yet.
In a revamped proposal announced Monday, the state Department of Water Resources seeks federal permits allowing installation of barriers in up to three of the next 10 years if the water outlook is bleak enough.
The decision to install the temporary barriers for up to eight months would be made on a year-to-year basis. But once it was made, the dams could be erected quickly, protecting water quality and sparing the use of scarce upstream reservoir water supplies to fight back salinity.
“We hope we do not have to install these barriers,” said Nancy Vogel, a spokeswoman for the Department of Water Resources. “But if things get really desperate, we want to be able to move quickly to protect water quality and conserve water.”
Vogel said her department wants to work out in advance what are acceptable environmental safeguards for the plan.
The barriers would be erected across three Delta channels: False River near Oakley and at Sutter and Steamboat sloughs near Courtland, south of Sacramento.
Delta water is used by 1.8 million people in the Santa Clara Valley Water District, 500,000 people in the Contra Costa Water District, 200,000 people in Alameda County Zone 7 Water District in the Tri-Valley, and 19 million people in Southern California.
The Contra Costa Water District is following the proposal and sees potential for the dams to help protect its water quality in very dry years.
“Anything to protect our water quality in a dry year is a good thing,” said Jennifer Allen, a district spokeswoman.
Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.
