April storms boost snowpack

May 05, 2003 11:00 pm

By LENORE RUTHERFORD

As if ordered by a doctor, a few good April storms are just what the Sierra Nevada needed.

At the beginning of April, the water content of the snowpack in the Stanislaus River watershed — which includes most of Tuolumne County — was at 72 percent of normal.

But by May 1, it had jumped 42 percent — to 114 percent of average.

In the Mokelumne River watershed, which covers most of Calaveras County, the snowpack jumped 30 percent, from 77 percent to 107 percent of average.

Another 8 to 10 inches of snow fell near Sierra summits last weekend, and more wet weather is forecast for this week.

Not only is the snowpack above normal for this year, said PG&E Hydrologist Terry Moore, based in San Andreas, but the spring run-off has been delayed because of cooler-than-average temperatures in April.

"When we finally get a stretch of clear, warm weather," he said, "the run-off will be a lot larger than last year, and that may be a safety issue for people visiting the area."

Moore said people always need to be careful in and around the water in the spring, because streams and rivers are swollen from the snowmelt.

"Last year, we were just 52 percent of normal for this time of year, and the runoff was really low," he said. "People tend to forget what normal looks like. They really need to be aware."

Moore said reservoirs are lower than normal, but will quickly fill when warm weather melts the snowpack.

Even before the April storms, PG&E expected to be able to fill its high country reservoirs, Moore said.

"The April storms were more important to the irrigation districts that serve the valleys than they were to the foothills," he said.

Moore said the only downside to the late storms will be if the summer comes on quickly and the snowpack melts off too fast — as more people are in and near the water.

But melt won't be an issue, at least for this week.