MONO LAKE, Calif. -- Leaning against a wooden rail, environmental activist Geoffrey McQuilkin took stock of a parched geological wonderland that had been altered by a weekend deluge.
The air was still thick with moisture, and this lake's tributaries were cascading down from surrounding mountains, swollen by cargoes of fresh snowmelt and rain. Frothy whitecaps and wavelets lapped over grass meadows that had been dry ground only a week ago. The lake's famous tufa formations -- for so long a symbol of California's lack of water -- were capped with snow.
Similar scenes were playing out at lakes and reservoirs across Northern California as weeks of heavy rain and snow brought them back to life. Throughout the course of California's nearly six-year drought, the declining water levels at these places became a stark symbol of the state's water shortage. Now, they serve as barometers of the state's rapidly evolving drought picture.
Lake Tahoe has risen 12 inches in just the last two weeks as the storms have dumped 33.6 billion gallons of water into the massive landmark, which measures 72 miles around and has a capacity for 37 trillion gallons of water.
As of Tuesday morning, 154 of the largest reservoirs tracked by the California Department of Water Resources had filled to about 97 percent of their collective average for the day, said Maury Roos, a longtime state hydrologist. Just a year ago, many were at or below 50 percent of average.
The storms dumped a combined 1.3 million acre-feet of water in those reservoirs from Jan. 1 to Tuesday, Roos said. That's about 423 billion gallons of water -- enough to serve more than 2.5 million families for a year.
The turnaround at the 1-million-year-old Mono Lake and its ecosystem has been particularly dramatic. Less than two years ago, it was within 2 feet of the level that state officials say threatens the alpine ecosystem at the base of the eastern Sierra Nevada. Officials worried there would be so little water that coyotes would roam on the dry lake bed and go after the large gull colony there.
Less than two weeks ago, hydrologists had worried that it would take a wetter than average winter to keep this drought-stricken body of saltwater at a level high enough to avoid having to halt diversions of its Sierra Nevada snowmelt to Los Angeles.
If the level drops below 6,377 feet above sea level, the city cannot export water from here. The California State Water Resources Control Board established the limit in 1994 to resolve a dispute between environmentalists seeking to protect the lake's wildlife and the city 350 miles away defending its long-held water rights.
Prospects for averting the crisis brightened significantly over the weekend after another storm drenched the slopes surrounding this high desert lake east of Yosemite National Park with enough rain and snow to raise its level by at least 6 inches.