RENEE MONTAGNE, host:
California is a place where people can appreciate a blizzard like the big snow-filled winter storms that unloaded on the state's Sierra Mountains last weekend. Mountain snow is a major source of water for California, and last year in the midst of a record drought, there wasn't much of it.
This winter, as NPR's John McChesney reports, there's new hope the state's tap won't run dry.
JOHN McCHESNEY: Last May, I went up to the Sierras to meet Frank Gehrke, the man who measures the California snowpack for the state Water Resources Department. We met at what's called the fill up station, one of the places the state has taken snow measures for years.
Usually, Gehrke plunges a tube into the snow here and takes a core that measures not only the depth, but the snow's water content. But not on this sunny day, last May.
Mr. FRANK GEHRKE (Snow Survey Chief, California Department of Water Resources): On average at this location this time of year, we should have about 16 inches of water content and that would represent about three feet in snow depth. And right now, it's bare. It's zero.
McCHESNEY: Not a hint of white, just a bare brown field bordered by wind-blown pines. It's so warm, the frogs are singing. Just what fill up station will look like this coming May is still unknown.
But recent storms here have raised hopes that California may not face a water crisis, at least this year. But Dave Hart, an engineer with the state Water Department, says media reports of 11 feet of snowfall were exaggerated.
Mr. DAVE HART (Engineering Associate, California Department of Water Resources): With all the press coverage that last storm it was not that huge.
McCHESNEY: About average for this time of year, Hart says still, things are looking better.
Mr. HART: We're in very good shape right now. It's all about what's out there that no one can really predict, which is storm activity more than a week out or more than 10 days out.
McCHESNEY: The next 68 weeks will tell a story, an immensely important story because the state of California is absolutely dependent on its Sierra snowpack. Between May and October, there's almost no rainfall here, so the snowpack acts as a vast reservoir during the dry months, gradually letting its water drain into the San Joaquin and Sacramento rivers - the aorta of the state's water circulation.
Or as Dave Hart puts it…
Mr. HART: Snowpack, obviously, is a sort of a time-release pill, if you'd like, for our water woes.
McCHESNEY: Inevitably, events like snowpack reduction raised questions about global warming and just as inevitably, scientists respond that annual weather variations are not reliable indicators of climate change.
But California is watching long-term climate conditions very carefully. The Sacramento and the San Joaquin rivers supply water to more than 20 million people, over half the state's population and most of its thousands of farms.
Michael Anderson, the water resource department's chief climatologist, takes the long view.
Mr. MICHAEL ANDERSON (Chief Climatologist, California Department of Water Resources): We've seen a decrease in April through July runoff in both the Sacramento and San Joaquin river systems.
McCHESNEY: Over what period of time?
Mr. ANDERSON: This is over the 20th century between 10 and 20 percent.
McCHESNEY: A trend that's hard to ignore in the nation's thirstiest state.
John McChesney, NPR News, San Francisco.