Water watchers see abundant summer supply, slim chance of flooding

Thursday, Feb. 18, 1999 | 9:01 a.m.

"There may be some stream runoff at times, but none of that is looking like a problem for the major stem rivers," said Larry Osterman, senior forecaster with the National Weather Service.

At the same time, there's enough water stored in the mountain snow to guarantee an above-average winter even if there isn't another storm. And a winter storm warning is posted for today with as much as a foot of new accumulation by evening above 6,500 feet.

The pattern the storms have been following is what helps rule out a recurrence of 1997's flooding because most of the snow has hit the west side of the Sierra.

Forecasters added, however, that all bets are off if there's an extended spell of warm, wet weather.

Snow water content in the runoff that feeds the Truckee River and the Tahoe Basin is where it should be on April 1, the end of the traditional winter storm season, according to hydrologist Dan Greenlee with the federal Natural Resources Conservation Service here.

That means history has been set for a second straight year with an unprecedented five consecutive wet winters. Up until now, three snowy years has been the maximum since records began last century.

Tree rings indicate periods of as long as 10 wet years before records began.

As of Wednesday, the snow water equivalent in the Tahoe snowpack was 169 percent of normal for this time of year and for the Truckee watershed 150 percent.

Snow water equivalent is different from total precipitation and more accurately reflects how much water will be available this summer.

The Carson and Walker watersheds aren't quite as high, measuring 121 percent and 116 percent of average.

"The earlier storms didn't reach that far," Greenlee said. "The Walker and Carson basins missed that snow. The last big storm put us over the top."

To the east, only the Lower Humboldt River is above average, at 121 percent water equivalent.

Just below the norm are the Upper Humboldt drainage at 95 percent, the Owyhee River runoff at 98 percent and the Snake River Basin at 99 percent.