San Nicolas Develops Endless Water Supply : Drought: The Navy installs a desalination plant that uses a reverse osmosis process to take advantage of the Pacific Ocean.

On San Nicolas Island, the four-year-old drought is over.

The barren, treeless island still hasn’t seen the first drop of winter rain, and its shallow wells have all but dried up.

But San Nicolas’ 225 residents are surrounded by the Pacific Ocean. And last month, they started drinking it.

With the opening of the state’s first major desalination plant on Oct. 11, San Nicolas Island is getting 12,000 gallons of drinking water per day from the ocean--half of what’s needed. A second plant will open next year, allowing the 27-square-mile island to cap its wells and get all its water from an unlimited source.

“We’re not going to lower the level of the Pacific Ocean,” said Lt. Cmdr. Steve Buske, who is in charge of the Navy-controlled island 65 miles southwest of Point Mugu, as he greeted reporters on a tour of the plant Thursday.

That potential for a boundless supply of water is prompting many coastal areas to look into desalination. Santa Barbara is studying the feasibility of a 1-million-gallon-a-day plant. A plant due to open on Santa Catalina Island next year will be capable of supplying more than 600 condominiums.

“If the drought continues, we’ll be seeing these plants all along the coast,” said Ted Kuepper, an environmental engineer for the Naval Civil Engineering Laboratory in Port Hueneme.

“The technology is there,” he said. “You just have to pay for it.”

Desalinated water costs about $7 per 1,000 gallons, Kuepper said. By comparison, the city of Ventura charges about 88 cents for the same amount.

For the Navy, desalination was much cheaper than the alternative--bringing in water by barge to serve the 60 enlisted personnel and 165 civilians who help track missiles from the Pacific Missile Test Center at Point Mugu. No families live there, but dozens of workers and contractors who commute to the island increase the demand for water.

This past summer, when as many as 600 people were working on the island some days, the water shortage was getting desperate, officials said.

In a normal year, San Nicolas gets only about six inches of rain, less than half the normal rainfall on the Ventura County coast. Since the drought began, San Nicolas has received even less rain.

This past summer, water had to be turned off except for two three-hour periods a day. Flights to the mainland were increased to cut down on the number of people staying overnight, and family members were no longer permitted to visit the island.

Mess halls switched to paper plates and plastic utensils to cut down on washing dishes. Car washing was banned, despite severe corrosion caused by the island’s salty air.

The solution was found in a desalination plant developed by the Marines in the early 1980s, after the Iranian hostage crisis prompted military planners to prepare for desert warfare. Today, the Marines have hundreds of similar plants, many of which are being used to supply troops in the Persian Gulf.

There are several ways of removing the salt that makes up 3.5% of salt water: distillation, freezing, electrodialysis and reverse osmosis, the process used on San Nicolas and in most commercial plants.

Reverse osmosis may sound high-tech and exotic, but it is actually just the reverse of a process that occurs everywhere in nature. The body’s cells absorb water by osmosis. So do the roots of a plant.

Under normal conditions, when salt water and fresh water are on opposite sides of a membrane or filter, the fresh water flows through the membrane into the denser salt solution. In effect, the fresh water wants to dilute the salt water.

By exerting pressure on the salt solution, however, the osmosis process can be reversed. If the pressure on the salt water is great enough, the natural flow is turned around. Fresh water flows out of the salt solution, creating more fresh water and saltier salt water.

The San Nicolas plant, housed in a building the size of a two-car garage, takes salt water from wells on the island’s northern beach and runs it through a series of filters under pressure. For every gallon of fresh water that emerges, about three gallons of water with a 5% salt content are produced.

The saltier water is returned to the beach. Kuepper said tests have shown that the saltier water is so diluted by the time it reaches the water table that it has no environmental impact.

The fresh water, meanwhile, is stored in tanks. It contains virtually no iron or other minerals and tastes sweet. Residents say it tastes a lot better than water from the island’s wells.

“The well water doesn’t taste too good,” said Scott Mullaley, a civilian firefighter who lives in Oxnard but works six-day shifts on San Nicolas.

Mullaley said the end of the island’s water crisis has raised expectations among residents.

“We’ve got a pool,” he said, “but it’s not operational--yet.”