O.C. to Be Water Bank for MWD

The Orange County Water District formally agreed Wednesday to help Southern California’s largest water wholesaler store water underground in exchange for several multimillion-dollar improvements to the county’s water-quality facilities.

The agreement, signed during a morning ceremony at the Orange County Water District’s headquarters in Fountain Valley, will allow the Metropolitan Water District, which supplies about half of Southern California roughly 2.5 million acre-feet of water annually, to store 63,000 acre-feet of water in the county’s ground-water basin. An acre-foot is roughly the amount needed to flood a football field with a foot of water, or 325,900 gallons.

“The concept here is to store water underground when it is available and then withdraw a portion of the water during dry or emergency years,” said Bob Muir, spokesman for the MWD. “Our concern is water-supply reliability.”

Using the space in ground-water basins across the region will also allow the MWD to avoid the costly and time-consuming process of building reservoirs. “The environmental licensing to build a reservoir can take up to two decades,” Muir said.

The MWD has entered into five basin-storage agreements in the last year, ranging from 3,000 acre-feet in La Verne to 100,000 acre-feet in Chino, Muir said.

The $29.8-million Orange County deal includes improvements to a phalanx of water wells that pump a pressurized hydraulic barrier that keeps seawater out of the ground water. Presently, the injection wells only slow, not stop, the ocean’s encroachment.

“Saltwater has slowly crept in over the years,” at a rate of hundreds of feet a year, said John C. Kennedy, assistant general manager for the Orange County Water District.

The level of contamination is negligible, Kennedy said. Even without the injection wells, saltwater intrusion would take years to make even a few of Orange County’s freshwater wells unpalatable.

Under the agreement, the capacity of the 26 injection wells will be doubled to 30 million gallons per day, the amount of water needed by the hydraulic barrier to stop the advancement of saltwater. The pact also calls for two new wells.

Other water-quality facility improvements include eight new water wells across Orange County that will serve as backups for the cities where they are located when they are not in use by MWD. The county also will get a 500-foot pipeline in Yorba Linda that will allow direct access to high-quality Northern California water.

The improvements will take about three years to complete, Kennedy said.

The Orange County basin covers about 360 square miles, from El Toro to the Los Angeles County line, and is up to 2 miles deep, Kennedy said. About a million acre-feet of water out of a total capacity of roughly 40 million acre-feet is accessible for consumption, he said.