Rainy-Day Planning for Dry Times

Historically, the aim of California water districts has been to develop so-called “assured supplies.” That did not mean just having enough to get by in any one year, but always having enough to meet demand in the worst imaginable drought. Under that sort of best-case operation, most districts would enjoy a surplus in most years. But times have changed. Even though population grows relentlessly in Southern California, it no longer is possible to just go out and get more water. The trick is to stretch the existing supply as far as it will go. To this end, the Metropolitan Water District of Southern California is going underground.

Metropolitan has approved expenditure of $1.2 million to begin work on development of an underground water-storage system that will help buffer the district against future dry years. The project is going forward in cooperation with the 132,000-acre Arvin-Edison Water Storage District, a big farm distributor of federal Central Valley Project water in the southeastern corner of the San Joaquin Valley in Kern County.

When Met has ample supplies available from the state Water Project, it will store some of the water--up to a total of 850,000 acre-feet--in the aquifer under Arvin-Edison. The program will increase the dependability of Arvin-Edison’s canal supply, which fluctuates from 10,000 to 353,000 acre-feet each year. The additional water stored in the aquifer will keep the water table from dropping and therefore make it more economical to pump from wells. The program also will keep the water table from falling to levels that would be harmful to crops. Maintenance of the storage would increase Metropolitan’s reliable water supply by about 100,000 acre-feet a year, enough to provide the residential needs of about 200,000 Southern California families.

The cost to Metropolitan will be in the purchase of up to 600 acres of land, construction of water-spreading grounds and the drilling of new wells--facilities that will become the property of Arvin-Edison. But these days, water is sometimes more precious than money. The program is a good one for both agencies and for the 14.7 million Southern Californians who rely on Metropolitan for some or all of their water.