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Big Calif. snowpack may not be enough yet to fill reservoirs

An impressive start of the winter season for California's snowpack may not be enough to fill reservoirs this summer if warmer storms or temperatures come along and wipe out the gains, experts say.
Tim Hearden

Capital Press

Published on January 5, 2016 11:33AM

Frank Gehrke (right), chief snow surveyor for the California Department of Water Resources, and DWR surveyor  John King conduct the season’s first manual snow survey Dec. 30 at a mountain station 90 miles east of Sacramento. So far, California’s snow water content is above normal for this time of year.

Courtesy of Calif. Dept. of Water Resources

Frank Gehrke (right), chief snow surveyor for the California Department of Water Resources, and DWR surveyor John King conduct the season’s first manual snow survey Dec. 30 at a mountain station 90 miles east of Sacramento. So far, California’s snow water content is above normal for this time of year.

Frank Gehrke, chief snow surveyor for the California Department of Water Resources, leads Frank Anderson of the U.S. Geological Survey through fresh snow to conduct the season’s first manual snow survey Dec. 30 at a mountain station 90 miles east of Sacramento. California’s snowpack is above normal for this time of year.

Courtesy of Calif. Dept. of Water Resources

Frank Gehrke, chief snow surveyor for the California Department of Water Resources, leads Frank Anderson of the U.S. Geological Survey through fresh snow to conduct the season’s first manual snow survey Dec. 30 at a mountain station 90 miles east of Sacramento. California’s snowpack is above normal for this time of year.


SACRAMENTO — California’s impressive early-winter snowpack may not be enough to fill reservoirs this summer if warmer rains or temperatures come along and wipe out the gains, experts say.

So far, many of the storms that have rolled into California this fall and early winter have been fed by a northern jet stream, bringing cold temperatures down from Canada and producing impressive levels of snow.

Even this week’s El Nino-driven storms were expected to bring snow levels as low as 3,500 feet, according to the National Weather Service. But if storms warm up and only drop snow above 7,000 feet, the snowpack could still be in long-term trouble.

“If it’s 5,000 feet, that’s still safe” for maintaining healthy snowpack levels, said Michelle Mead, a National Weather Service warning coordinator in Sacramento. “It’s really going to be individual storm dependent.”

This week’s active system comes after state snow surveys chief Frank Gerhke and others conducted the season’s first manual snow survey of the season Dec. 30 at a mountain station about 90 miles east of Sacramento.

Gehrke found a snow depth of 54.7 inches — 16 inches more than the average depth measured there since 1965 — and 16.3 inches of water content, 138 percent of the Jan. 1 average for the site, according to the state Department of Water Resources.

But as of Jan. 5, California’s statewide snow water content was 97 percent of normal for the date, down from 105 percent of normal on Dec. 30, according to the DWR’s California Data Exchange Center.

“Clearly, this is much better than it was last year at this time, but we haven’t had the full effect of the El Nino yet,” Gehrke told reporters after conducting his survey. “If we believe the forecasts, then El Nino is supposed to kick in as we move through the rest of the winter. That will be critical when it comes to looking at reservoir storage.”

The heavy snowfall so far this winter “has been a reasonable start, but another three or four months of surveys will indicate whether the snowpack’s runoff will be sufficient to replenish California’s reservoirs by the summer,” DWR director Mark Cowin said in a statement.

In any case, more than four years of drought have left a water deficit around the state that may be difficult to overcome in just one winter season, Gehrke said.

One or two warm storms wouldn’t be enough to wipe out the snowpack, Mead said. The snow acts as a sponge and absorbs water that falls as rain until it’s saturated, then it begins to melt.

“We do have a pretty good snowpack up there now,” she said. “It’s still at or just above average.”

But warmer rainfall and temperatures typically start to melt the snow in the spring, which keeps the reservoirs flush with water in the summer months. If the snow melts earlier than normal, there may not be enough water left over this summer.

“With an El Nino year, we can’t for sure say when that will happen,” Mead said, referring to snow melt.



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