California Needs to Move Cautiously on Desalination

Economic, Environmental, and Social Costs Still Outweigh Technological Gains

June 27, 2006, Oakland, CA: Having completed a year-long California-focused analysis of desalination, Oakland’s Pacific Institute concludes that most of the state’s seawater desalination proposals are premature. According to their report, “Desalination, With a Grain of Salt,” most if not all of the 21 desalination projects proposed in California fail to adequately address economic realities, environmental concerns, or potential social impacts. Recent gains in desalination efficiency are being offset by rising interest rates and increases in energy and construction costs. Even the cheapest estimates exceed the costs of conservation and efficiency improvements, fixing leaks, and other sources of new supply. As a result, desalination remains an extremely expensive source of fresh water for Californians.

“Desalination will be part of California’s water future, but the future’s not here yet,” said Dr. Peter Gleick, President of the Pacific Institute. “Most California communities can find additional water, quicker and for less money, by improving efficiency and management.”

Desalination is energy intensive, making its already high costs vulnerable to rising energy prices. Electricity accounts for 44% of the typical water costs of a reverse-osmosis plant. An energy rate increase of 25% increases the cost of produced water by 11 percent. Energy price uncertainty creates costs that are ultimately paid by water users, but project cost estimates often omit such considerations.

Cost Breakdown of Typical Reverse Osmosis Desalination Plant

Statewide, proposals range in size from a small plant providing water for a private development along Cannery Row, Monterey to much larger plants in Southern California that would be among the largest desalination plants in the United States. The total capacity of the proposed plants could amount to approximately 450 million gallons per day, which would represent a massive 70-fold increase over current seawater desalination capacity. Map of Proposed Desalination Plants in California

In Southern California, interest in desalination is driven by concerns about drought reliability, population growth, and the desire to reduce dependence on outside water sources. The capacity of the region’s proposed plants totals 300 million gallons per day, or about 7% of the region’s average daily water needs in 2000. If built, four of the proposed plants would be among the largest in the country.

Concerns about drought, water supply limitations, overuse of water needed for ecosystems, and growth moratoriums are driving Central California’s projects. The Pajaro-Sunny Mesa/Poseidon plant proposed for Moss Landing would be the largest in the region, producing 20-25 million gallons of fresh water per day (MGD). This plant is in direct competition, however, with the smaller California American Water Company plant, which would use the same Duke Energy site to produce 11-12 MGD.

Four desalination plants are proposed in Northern California. The purposes of the proposed plants vary, ranging from improved reliability during droughts and emergencies to meeting anticipated growth needs and providing environmental benefits. With the exception of the Marin Municipal Water District, which is operating a pilot plant, agencies in Northern California are still in the early planning stages and no project is likely to be built before 2010.

“Our communities cannot be rushed into desalination projects – the economic, environmental, and social costs of desalination are too high,” said Heather Cooley, lead author of the report. “Local, state, and national laws do not sufficiently protect our communities from costly mistakes.”

“While desalination can produce high-quality, reliable water, it can also have significant impacts on marine ecosystems,” said Gleick. Marine organisms can be crushed against intake-pipe screens or sucked in and killed by the desalination process. Further, the discharge of the highly salty waste brine – which is sometimes laced with processing chemicals and toxic metals – can harm local fish populations and accumulate in the food chain.

The Institute also finds that desalination can have impacts on community development. New water sources along the coast can lead to unanticipated and unplanned new growth along the coast.

“Desalination, With a Grain of Salt” report is available electronically (free and online at You can also order a hard copy ($20) online or by calling 510-251-1600.

Founded in 1987 and based in Oakland, California, the Pacific Institute is an independent, nonprofit research center dedicated to protecting our natural world, encouraging sustainable development, and improving global security.