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Snowpack remains a water concern

Posted at 10:49 p.m. PST Thursday, Feb. 22, 2001


Mercury News

What a difference a few Pacific storms can make. Just a few weeks ago, meager winter rainfall spurred concerns about drought threatening the state. But recent rains, and the forecast that a parade of storms will sweep over California in the next few days, have all but drowned most -- but not all --of those worries.

While rainfall is creeping up to average levels around Northern California, the Sierra Nevada snowpack still contains far less water than normal for this time of year.

The National Weather Service expects the next storm Saturday, with off-and-on wet weather into midweek. As of Thursday afternoon, San Jose's rainfall since the season began July 1 had increased to 9.60 inches -- 96 percent of normal.

Today, Santa Clara County's 10 reservoirs are half full, with more than a month of the rainy season to go, and the valley's underground water basin is full.

But it's a mixed picture.

Despite a near-miraculous recovery from the poor conditions three weeks ago, the Sierra Nevada snowpack still contains on average only 70 percent of the amount of water it normally has in late February. And that melting snowpack provides about half the water Santa Clara County needs.

Those who manage California's water supplies hope more storms will turn this into a normal rainfall year, but expect a little less. That's after six consecutive winters with above-normal rain and snow that followed five years of drought.

``We were just limping along, but it's really kicked up in the past few days,'' Jeff Cohen, spokesman for the state Department of Water Resources in Sacramento, said Thursday. ``We're hoping we'll pull out near an average year. Anything above that would be phenomenal.''

California gets the bulk of its rain and snow from December through March. This winter, the storms were few and far between -- until February.

``This happened rather quickly,'' said Mike Di Marco, spokesman for the Santa Clara Valley Water District, which manages the 10 reservoirs, underground basin and imported water supplies in the county.

``Despite the earlier dry weather,'' he said, ``February has turned out to be a fabulous February for the water district.''

Now that several storms have saturated once-dry soil in the hills around the valley, ``any rainfall we get from here on out is going directly into the reservoirs and creeks,'' Di Marco said.

Santa Clara County's basic water system consists of 10 reservoirs, which catch winter storm runoff that otherwise would run into the bay. During dry months, the water is released from the dams to percolate slowly underground in creek beds and ponds. Retail water companies pump it from wells to supply their customers.

On Thursday, the reservoir system was half full; there hasn't been enough storm runoff to force water releases from the dams for flood control purposes, said water operations planning manager Jeff Micko.

But the local system supplies only half of the approximately 372,000 acre-feet of water that Santa Clara County uses in a year. An acre-foot is 325,800 gallons, a two-year supply for a typical family of four.

The rest comes from the Sierra Nevada snowpack and reservoirs, flowing into the environmentally fragile Sacramento-San Joaquin River Delta and through state and federal aqueducts and pipelines into the South Bay.

And there's the big question mark.

At the first of the month, the snowpack's water content was about half of normal, leading state and federal water managers to issue glum news to the cities and farms that depend on it.

On Feb. 15, federal officials said their Central Valley Project would deliver 65 percent of the water it has contracted to provide to urban areas such as Santa Clara County, while the State Water Project would provide only 20 percent of what is expected.

Now, with the wet weather, the two projects are likely to deliver more water, although new figures won't be available for several weeks. But the Sierra snowpack today is only 57 percent of a normal winter's total with little more than a month to go, Cohen said. ``We hope we can overcome the odds and have an average year, but the math is against us.''

If that happens, Santa Clara County would have to make up the loss by pumping more water from its underground reserve, Di Marco said.

``Fortunately, it's full and would get us through one year of less than normal water supply,'' he said.

A LOOK AT THE WATER SUPPLYNorthern California's water supply outlook has changed dramatically since the storms began sweeping over the state on a regular basis this month.

Contact Frank Sweeney at or (408) 920-5675.

-- Swissrose (, February 23, 2001

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