California's 3-year-old drought has thrust seawater desalination into the spotlight as San Diego County, Santa Barbara and other cities push ahead with treatment plants that will soon turn the Pacific Ocean into a source of drinking water.
Desalination has emerged as a newly promising technology in California in the face of a record dry spell that has forced tough new conservation measures, depleted reservoirs and raised the costs of importing fresh water from elsewhere. But experts warn that converting seawater to drinking supplies remains an expensive, energy-intensive enterprise that has had mixed success in places like Australia and Florida.
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The biggest ocean desalination plant in the Western Hemisphere, a $1 billion project under construction since 2012 on a coastal lagoon in the California city of Carlsbad, is nearly completed and due to open in November, delivering up to 50 million gallons of water a day to San Diego County.
That is enough to supply roughly 112,000 households, or about 10 percent of the county's drinking water needs, according to Poseidon Resources, the Connecticut-based company behind the facility.
Poseidon has a second seawater desalting project of similar size under development in Huntington Beach, south of Los Angeles, and is seeking a final permit to begin construction next year.
Meanwhile, the city of Santa Barbara is taking steps to modernize and reactivate a much smaller $34 million desalination plant built during an earlier drought but moth-balled after a trial run in 1992, when that water crisis abated. With water supplies dwindling again and no relief in sight, Santa Barbara leaders are contracting with a firm to design upgrades for recommissioning its facility for $40 million. Annual operating expenses would run about $5.2 million.
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If approved as expected in June by the City Council, the plant would open in the fall of 2016, initially delivering nearly 3 million gallons of water a day - about 30 percent of municipal demand - and ramping up capacity as needed, said Joshua Haggmark, Santa Barbara's water resources manager.
Another 15 to 17 seawater desalting plants are in the design or planning phase around the state, said Heather Cooley, water program director for research nonprofit Pacific Institute.
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But Cooley said the high costs of constructing and running such facilities pose challenges.
"There's a real risk in building a plant before you need it, or building it to meet a short-term need rather than a long-term need," she said, pointing to Santa Barbara's own experience two decades ago, as well as plants that were constructed and later idled or scaled back in Australia and Tampa Bay, Florida.
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She said water managers should be looking at a range of measures that include increased conservation, wastewater recycling and stormwater recapture.
Poseidon executive Scott Maloni said desalination is not meant as an emergency drought solution but part of an answer to a chronic problem and a way to replace some water imports.
Critics of desalination have cited environmental drawbacks, such as harm to marine life from intake pipes that suck water into the treatment plants and the concentrated brine that gets discharged back into the ocean.
But advocates tout its potential for easing environmental consequences of diverting freshwater from rivers and streams and pumping it to urban centers.
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The process of forcing seawater at high pressure through special membranes to remove salt requires large amounts of energy, which has long made it prohibitively expensive.
But costs of importing water have steadily risen to about the same as desalinated water, minimizing the impact on the household water bills, Haggmark said.
Cooley said, however, those rates are certain to go up with rising energy costs.
