California's water fortune is told at Gin Flat

FOR THE RECORD:
Snow survey: An article in Monday's Section A about the Gin Flat snow survey in the Sierra Nevada gave the name of the Big Oak Flat entrance to Yosemite National Park as Big Oat Flat. —

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This place is like a Rosetta Stone for California's water supply. It's where the convergence of snow, sun and temperature enables scientists to predict floods or drought. It's where they have installed sophisticated equipment to help understand how climate change is altering snow melt in the Sierra, a source of water for millions of Californians.

"Gin Flat's always been the place where we try things and invest first," said Michael D. Dettinger, a U.S. Geological Survey hydrologist based at Scripps Institution of Oceanography in La Jolla.

Although the state oversees more than 300 survey sites, what makes Gin Flat unique is its location, an elevation in Yosemite National Park just above the point where rain commonly turns to snow. That makes it an ideal spot to test the premise that a warming climate will produce more rain at higher elevations -- a shift that would bring more flooding and less snowpack to fill California reservoirs in mid-summer.

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FOR THE RECORD:
SNOW SURVEY: A March 3 article in Section A about the Gin Flat snow survey gave the name of the Big Oak Flat entrance to Yosemite National Park as Big Oat Flat.

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These days, with water woes plaguing the state, readings at Gin Flat will ultimately help determine how much more it could cost Californians to drink a glass of water or take a shower, or if they can water lawns without restrictions.

That is why Gehrke, 60, didn't hesitate to ski three miles up the mountain last week, hauling a sled loaded with 60 pounds of fuel cells and tools. He is California's snow survey chief, a man respected as the don of the Sierra snowpack. As caretaker of Gin Flat, he needed more power to fuel all the equipment at the site he helped develop.

Last week, his agency, the state Department of Water Resources, reported that Sierra snowpack was at 118% of normal for this date, compared with 63% of normal at this time last year, the driest year on record for Los Angeles.

But Gehrke is a cautious man, and never more so than when explaining snowpack surveys.

"We could slide back to below average. A March without snow could do it," he said. "A lot of the reservoirs are pretty low from last year."

That would be bad news for Southern California, which depends heavily on imported water, about half from northern mountains and the rest from the drought-stressed Colorado River. Further straining supplies, a court decision protecting a rare fish in the Sacramento-San Joaquin River Delta has reduced deliveries to the south by 30%. To comply with court stipulations, state officials last week cut southward flow for seven days by 75% of normal.

Amid fears of shortages, water rates probably will rise. Directors of the region's water wholesaler, the Metropolitan Water District, will vote March 10 and 11 on a proposed 14.3% rate increase starting Jan. 1, 2009, in part to buy extra water. More rate increases are expected in 2010 and 2011.

Worried state and local officials look to data from locations like Gin Flat for assurances that the Sierra will continue to provide a steady stream of water to keep the economy growing and water rates low.

Gehrke cannot offer the certainty they crave, he said one morning last week over a hearty eggs-and-hash-browns breakfast at a restaurant en route to Gin Flat. He is not one to speak in sweeping terms. His tone is matter-of-fact.

"When it's wet or dry, people go out and get into hyperbole about how much snow they've seen," he said

"We always think it's good to keep things grounded and not get carried away by the moment."