Thirsty State Looks to Sea for Water

PARCHED by four years of drought - and with forecasts of more to come - California is turning to seawater to help quench its growing thirst. The state's average influx of 600,000 new residents a year over the 1980s has accelerated the depletion of many communities' already-tenuous freshwater supplies. Over the same period, various technologies have been developed and improved - helping make seawater a viable alternative to conventional sources. Thus, many communities are not just seeking to alleviate the current drought by turning saline water into fresh. They are investigating desalination as at least a minor contributor, and perhaps a major one, to solving long-term water problems.

First plant opened

San Nicolas Island (off the coast between Los Angeles and San Diego) opened the state's first major desalination plant on Oct. 11, generating 12,000 gallons of drinking water a day from the ocean. A second plant will open this year, enabling the 27-square-mile island to seal its groundwater wells and get all its water from the ocean.

The Marin [County] Municipal Water District currently operates a pilot desalination plant near the north end of San Francisco Bay. Although the bay is less salty than the ocean, it is more clouded with silt from rivers, industrial waste, and microscopic marine life. The plant is experimenting with various types of pre-treatment filtration systems to clean bay water before it goes into the desalination plant. The district hopes to raise $55 million to $65 million to build its own desalting plant and is developing a proposal for voters by November 1991.

Santa Barbara is months away from building a $25 million plant to supply one-third of the city's needs by 1992. Pending city approval, Ionics Inc., a company headquartered in Watertown, Mass., will build, own, and operate the plant to supply water to the city for five to 10 years. Perhaps hardest hit by the drought, Santa Barbara's main water source - the Cachuma Reservoir - is at 15 percent capacity. Its secondary source, Gibraltar Reservoir, is empty.

``Even if we get normal rainfall for two years, we'll need some kind of supplemental supply,'' says Pete Ramsdell, city spokesman for drought affairs.

The Metropolitan Water District (MWD), which supplies water to southern California, is considering building several very large distillation operations, utilizing waste heat from electricity-generating plants for greater energy efficiency.

``We see desalting water as a long-term solution,'' says MWD's Tim Skrove, who is studying the feasibility of demonstration projects. ``But it will be years before anything large-scale will be in place.''

Other California communities considering desalination include San Luis Obispo, Monterey, San Diego, Morro Bay, Ventura, and Oxnard. A plant due to open on Santa Catalina Island this year will supply water for more than 600 condominiums.

``If there were viable alternatives for importing water we wouldn't be doing this,'' says Robert S. Castle, senior engineer of the Marin Water District. ``But all of the easy water in California has been spoken for for quite some time.''

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