As part of efforts to boost California’s water supply in the wake of its historic, five-year drought, state water officials have decided to award $34.4 million in grants to eight proposed desalination projects across the state, including one in the Bay Area, at Antioch.
The money comes from Proposition 1, a water bond passed in November 2014 by state voters during the depths of the drought.
Highlighting the expensive cost of ocean desalination, however, all but one of the eight winning proposals are for brackish desalination, not ocean desalination. Brackish desalination is a process in which salty water from a river, bay or underground aquifer is filtered for drinking, rather than taking ocean water, which is often up to three times saltier and more expensive to purify.
“Desalination can play an important role in California’s water future,” said Richard Mills, water recycling and desalination section chief for the state Department of Water Resources, which chose the winners.
“But we want to be protective of the environment and provide water at reasonable cost,” he said. “That’s been the challenge for desalination, in terms of why we can’t just build a lot of plants anywhere to solve our water problems. We feel the judicious use of desalination can allow us to use water that’s more immune from drought and which can help reduce diversions from the Delta and other sensitive ecosystems.”
Ocean desalination costs between $2,000 and $2,500 an acre-foot. Brackish desalination is roughly half that cost. An acre foot is 325,851 gallons, or the roughly amount of water a family of five uses in a year.
“More of the grant money is being awarded to brackish desalination than seawater desalination. That’s not surprising,” said Heather Cooley, water program director for the Pacific Institute, a non-profit research organization in Oakland. “More communities are looking at brackish desal because it’s less expensive, it can have fewer environmental impacts and it isn’t limited to coastal communities.”
Three projects were awarded $10 million each to help with construction. Among them is the Antioch Brackish Water Desalination Project, which is estimated to cost $62.2 million. The city already takes water from the San Joaquin River on the Antioch waterfront as it is flowing from the Delta into San Francisco Bay, and uses it as part of the water supply for 110,000 people. But in the summer and fall months, when less Sierra snow is melting and less freshwater is flowing into the Delta, the water becomes too salty to drink.
Under the plan, the city would build a desalination plant at its existing water treatment plant, filter the water and generate 6 million gallons a day of freshwater. The 2 million gallons of brine left over would be sent through a new 4-mile-long pipeline to the Diablo Wastewater Treatment Plant near Pittsburgh, where it would be blended and diluted with treated sewage that already is pumped back into the bay.
The other projects that received $10 million are the Doheny Ocean Desalination Plant in Orange County, which is estimated to cost $110 million, and the North Pleasant Valley Desalter Project, a $32 million brackish water project in Camarillo, in Ventura County.
The remaining projects received grants of $650,000 to $1.5 million to pay for studies and pilot projects, all in Southern California.
There was $93 million to award under Proposition 1, so applicants that did not receive money — including a project in Monterey County that state officials said needed to provide more detail — can still apply for the remaining $58 million, Mills said.
Although ocean desalination is a major source of drinking water in Israel, Saudi Arabia and other Middle Eastern counties, in California there are currently just five active ocean desalination plants that provide less than 1 percent of the state’s drinking water.
The largest, by far, is a $1 billion plant on the coast in Carlsbad, 35 miles north of San Diego, that opened in 2015. The plant, whose water is purchased by the San Diego County Water Authority, is the largest desalination plant in the United States. It generates up to 56,000 acre-feet of water a year — roughly 8 percent of San Diego County’s water supply. But the cost is high, ranging from $2,131 to $2,367 an acre-foot depending on how much is produced, which is double the price that Metropolitan Water District of Southern California charges for the same amount of water from other sources like local dams, the Colorado River or the Sacramento-San Joaquin Delta.
The others are in Santa Barbara, Catalina Island, Marina and San Nicholas Island. Together they have the capacity to produce about 4,000 acre-feet a year.
About a dozen other ocean desalination projects are still pending, or in various states of environmental studies, design or funding. The most prominent are in Huntington Beach, where Poseidon, the company that built the Carlsbad plant, has proposed a similarly sized plant but is running into opposition from environmental groups worried about the impact on fish and other aquatic life, and Monterey County, where Cal-Am Water, a private company, is proposing to use slant wells off the beach to build a plant.
“Even after last year’s rain in California, good planning is still going forward for both brackish and ocean desalination,” said Paul Kelley, executive director of Cal Desal, an industry group. “Hopefully a couple of ocean desalination projects will break ground in the next two or three years, and on the brackish side, I think anywhere from five to 10 will move forward.”
Some places have rejected projects over concerns about their impacts on energy use, ocean life and growth. Plans for a $115 million desalination plant in Santa Cruz were withdrawn by city leaders after voters in 2012 voted to approve a measure banning desalination unless approved by a vote of the people.
Brackish desalination is growing faster. As of 2013, there were an estimated 24 brackish desalination plants in California, which produced about 96,000 acre feet of water a year. Another three were in design and construction, with 9,000 acre feet more, and 17 were proposed with 81,000 acre feet capacity.
The Alameda County Water District opened a brackish desalination plant in Newark that has been desalting about 14,000 acre-feet of water a year since 2013 — about 40 percent of the district’s supply.
“Technological advancements are happening all the time,” said Kelley. ” And the cost of water keeps going up, so the cost of desalinated water isn’t as out of proportion.”