California Water Professionals Worry About La Nina's Effects

Sept. 28, 2007

After last year's bone-dry winter, it wouldn't be surprising if many California water managers resorted to rain dances.

They'd better keep dancing.

Using one of the best scientific crystal balls available, weather experts say a moderate La Nina is developing. That's a weather system typically associated with minimal rain in the Southwest and above-average precipitation in the Pacific Northwest.

La Nina can be a mixed bag in the Bay Area, but it has meant below-average rainfall totals more often than not.

National drought experts -- who say every part of California is already either "abnormally dry" or experiencing moderate to extreme drought -- agree that many parts of the state could be in for a long, dry winter.

If California gets a normal amount of rain, or even slightly less than normal, many cities still will likely have a sufficient water supply. But if the rainfall is light or too early, or if the Sierra, whose melting snowpack each spring is one of the state's primary water sources, doesn't get enough snow, it could push some regions squarely into a severe drought. Then strict water rationing would no doubt have to be implemented.

"It's a little early to panic, but people ought to be thinking about it. We certainly are," said Bill Kocher, director of the city of Santa Cruz Water Department, which in May restricted hours for watering lawns.

La Nina occurs when the ocean water is cooler than normal in the tropical Pacific, impeding the formation of clouds and tropical thunderstorms. Its impact is greater the closer you get to the equator.

During the last true La Nina, in 2000-01, the Bay Area saw less rainfall than usual. But two years earlier another La Nina left the region wetter than normal. The reverse was true for Los Angeles. In 2000-01 there was above-average rainfall; in 1998-99 there was less.

Source: Oakland Tribune