AGENCY DRILLING WELLS TO STORE WATER FOR FUTURE\Calleguas project under way.

Byline: Michael Coit Daily News Staff Writer

Water needed to quench the thirst of the Las Vegas development boom has been pumped into wells since 1989, where it is stored for use in years to come.

Now the effort to stave off drought in the midst of arid Nevada is being duplicated in semi-arid Ventura County.

The first of 30 wells is being drilled in the Las Posas Valley by the Calleguas Municipal Water District to store drinking water that will be pumped in dry years or if a major earthquake severs the county's connection to the State Water Project.

"We're not inventing anything new. We're just trying to utilize the resources we have," said Don Kendall, Calleguas' general manager.

Hydrologists and planners for the Southern Nevada Water Authority are accustomed to making maximum use of resources.

Beginning in 1987 with an idea of storing drinking water underground, the Nevada agency officials used computer models to learn whether water could be contained underground and if wells would remain viable if not used for years at a time.

A test well drilled in 1988 was successful and the agency has been drilling wells since 1989.

"We have the largest injection well project of potable water in the U.S.," said Michael Johnson, the agency's senior hydrologist.

"We did this basically to commit to Nevada's allocation of Colorado River water. It's banking water for future use," he explained.

Johnson noted that 35 wells have been drilled and the agency has plans for as many as 100 in all.

At the end of 1995 the agency had pumped 102,999 acre-feet of water into the underground storage wells and only pumped out 3,107 acre-feet.

An acre-foot of water is 325,872 gallons, enough to serve two average-size families for a year.

Calleguas began inquiring about the project some three years ago, followed by water agencies from Arizona, Utah, Arkansas and Florida, Johnson said.

"We helped them out on the feasibility. We summarized the success of our program, some of the technical issues," Johnson said of the collaborative effort.

Important factors include drilling costs and electrical costs to inject and extract water, the composition of rock and soil, and the boundaries of an aquifer.

The Southern Nevada agency, for instance, pumps water into storage wells from October to May, when electrical costs are reduced compared with peak demands during the long, hot Nevada summer.

"Every system is unique and there's a potential set of problems associated with it," Johnson said.

Calleguas officials hope to boost storage capacity with the Las Posas project to an amount that would more than triple current annual demand from retail agencies serving some 500,000 Ventura County residents.

Kendall, the general manager, said the project was chosen over more conventional alternatives, such as a massive reservoir above ground.

"I think, over time, we've become so complacent. It's a lot easier to build a concrete reservoir and put water in it and it's a lot easier to manage," he said.

A contractor began drilling the first well earlier this month with three more to follow.

If the initial wells perform as expected, with pumps set up to inject and extract water, Calleguas officials hope to complete the 30 wells within about six years.

"The process had taken longer than I expected. We had a few design issues, but nothing major," Kendall said. "We're starting up and you're going to start seeing it snowball."

The Las Posas project calls for injecting imported state water in winter and pumping the water in summer during peak demand periods. The supplies also would help Calleguas ensure deliveries to its retail customers during drought, and water held in underground storage also could be pumped if the district's main supply line in the Santa Susana Pass was damaged during an earthquake.

The series of wells would be in an aquifer that reaches from Moorpark west through the Las Posas Valley.

The 30 wells could store as much as 300,000 acre-feet of drinking water.

Calleguas received $6 million to develop the first five wells from the Metropolitan Water District, which has a fund to support projects that improve the region's water supply.

The MWD has 27 member agencies, including Calleguas, in six Southern California counties. Calleguas buys drinking water from the MWD imported from the State Water Project and sells supplies to 21 cities and retail agencies.

If the initial wells are viable, Calleguas is counting on additional MWD funding to complete the $50 million project.

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Photo Drilling work has started on Calleguas Municipal Water District storage wells in the Las Posas Valley. Dusty Locke/Special to the Daily News