The biggest blizzards are over. But as state water officials head into the Sierra Nevada on Thursday for the annual April 1 snowpack reading — the most important of the year for planning summer water supplies — California still has a huge amount of snow covering its highest mountain peaks, an avalanche that has buried the state’s punishing drought.
On Tuesday, the statewide Sierra snowpack stood at 164 percent of its historic average, a massive accumulation of new water. It’s the largest snowpack since 2011, when it was 171 percent of normal on April 1.
“In some of the Southern Sierra elevations, it’s kind of amazing,” said Frank Gehrke, chief of the snow survey program for the state Department of Water Resources in Sacramento. “There’s 30 to 50 feet of snow in some areas.”
At the height of the drought two years ago, the April 1 snowpack was 5 percent of its historic average, exposing a vast range of rock and dirt that normally would be covered with deep snow.
What happened?
In January, atmospheric river storms barreled in from the Pacific Ocean, no longer blocked by the high-pressure “Ridiculously Resilient Ridge” that had diverted so many storms during the height of the drought. Pounded relentlessly, the Sierra received so much snow that Interstate 80 and Highway 50 were regularly closed under enormous drifts. On some days, even ski resorts had to close because chairlifts and parking lots were hopelessly buried, and the power was out. In one storm on Jan. 8, wind gusts reached 174 miles per hour on the peaks atop Alpine Meadows ski resort near Lake Tahoe.
“It’s been a crazy year,” said Michael Reitzell, president of the California Ski Industry Association.
Those storms tapered off, and warmer conditions have brought less snow in March. Even so, more snow is forecast for Thursday, and the size of this winter’s snow surplus has been exceeded only three times since 1970 — in 2011, 1995 and 1983.
Squaw Valley ski resort, which has received 54 feet of snow so far this year, plans to stay open until July 4. Further south, the town of Mammoth Lakes in Mono County called in the National Guard earlier this month to help it remove some of the 44 feet of snow that has piled up along its streets and businesses.
“During the drought most of the snow was gone by June,” said Roger Bales, director of the Sierra Nevada Research Institute at UC Merced. “I’m thinking that this year there will be snow well into July and August, particularly at higher elevations.”
Meanwhile, since October, Lake Tahoe, which is 22 miles long, has risen 5 feet.
Every year, the Sierra snowpack accounts for roughly a third of California’s water supplies. A vast “frozen reservoir” that stretches 400 miles from Lassen County in the north to Tehachapi Pass in Kern County, the snow steadily melts in the spring and summer, flowing down rivers and into reservoirs, also replenishing depleted groundwater.
This year, however, many of those reservoirs are already full or near full. That’s making dam operators nervous. While only a year or two ago they were looking at dangerously low water levels, today they are emptying reservoirs to provide space to capture the billions of gallons of water from melting snow in the weeks and months ahead. Without that space, one or two warm rain storms could increase the melting rate, filling reservoirs to the top and causing uncontrolled releases and floods in cities and towns downstream.
“There is always a balancing act that dam owners have to play,” said Andrea Pook, a spokeswoman for the East Bay Municipal Utility District, which provides drinking water to 1.4 million in Alameda and Contra Costa counties.
For the past 60 days, the district has fully opened the outlet pipes at its largest reservoir, Camanche Lake, in the foothills 10 miles east of Stockton, lowering the reservoir level by about 13 feet since Feb. 24. It is now 75 percent full, but given the huge snowpack in the watershed of the Mokulumne River above it, the reservoir should be 100 percent full by this summer, Pook said.
“We have to make sure we have sufficient water storage for our customers, but also make sure we do our best to minimize impacts on flooding,” she said. “The timing is critical. We make decisions daily about how to handle it.”
Overall, the state’s 46 largest reservoirs are 111 percent of their historic average. Every major city in California has seen large amounts of rainfall this winter, with San Francisco and Oakland at 144 percent of the historic average for the end of March, San Jose at 123 percent, Sacramento at 189, Fresno at 143 and Los Angeles at 141.
Additionally, 92 percent of California is no longer in drought conditions, according to the U.S. Drought Monitor, a weekly report by the NOAA, the U.S. Department of Agriculture and the University of Nebraska.
So when is Gov. Jerry Brown going to rescind or amend the drought emergency order he signed in January 2014? He hasn’t said, although sources say it could be in mid-April.
At a press conference Feb. 24, a journalist asked Brown if he was getting ready to lift the drought emergency.
“Yes is the answer,” he said. “But not yet. Not until the end of the rainy season.”
