Profound rebound in Sierra snowpack
Levels among highest in decades after dark drought years
Two years ago, when state water managers trekked into the High Sierra to measure snowpack at its typical springtime peak, they found what would become a lasting image of one of California’s bleakest moments: barren earth.
But Thursday, as surveyors made the same hike to the same spot, the state could hardly be more removed from the darkest days of the drought.
Long-dry mountainsides are buried in as much as 20 feet of snow. Icy summits have begun filling rivers and reservoirs with enough runoff to ensure water supplies for years. The ski season, according to reports from the slopes, is likely to extend through the Fourth of July.
The astonishing recovery was confirmed by the state surveyors who measured snowpack at Phillips Station, south of Lake Tahoe in El Dorado County, at a whopping 183 percent of average for the date.
More important, if a little less impressive, the Sierra-wide snowpack was determined to be one of the biggest in decades, at 164 percent of average, according to the state’s system of automated sensors.
That compares with a dismal 5 percent just two years ago when surveyors found virtually no snow at the 6,873-foot-elevation Phillips Station.
“It’s a dramatic turnaround,” said Mike Anderson, state climatologist with the California Department of Water Resources. “We’ve spent a lot of time at the low end of the distribution, so it’s nice to get one back on the other end.”
The state measurements, which don’t gauge the depth of the snow but its water content, are critical this time of year. That’s because the peaking levels allow water managers to forecast the spring and summer melt. The runoff provides about a third of California’s water.
Already, many of the reservoirs that stood half full, or less, for years during the drought are brimming with water as the state has benefited from a near-constant barrage of storms this winter.
San Francisco water managers expect to soon fill their system of
lakes and reservoirs, putting away enough water to make it through a theoretical 8½-year dry period. In 2015, there were just three years’ worth of water — when strictly rationed — in reserve.
Most water agencies had even less. The shortages set off a wave of mandatory conservation rules that forced Californians to watch their lawns turn brown and shorten their showers. In farm country, those who couldn’t turn to groundwater had to fallow fields, and crop yields fell.
Now, almost all water suppliers, including the San Francisco Public Utilities Commission, are having to release water from behind their dams to make room for the incoming runoff. Without enough space in the reservoirs, communities downstream are threatened with uncontrolled outflows.
“It’s a balancing act,” said Charles Sheehan, spokesman for the San Francisco water agency, which has lowered its Hetch Hetchy Reservoir in Yosemite National Park to 83 percent of capacity. “We need to stay ahead of all that snowmelt.”
Thursday’s snow level for the Sierra ranks as the seventh largest in the key spring reading since 1950. It’s just below the measurement from 2011, the last wet year before California descended into drought.
Most of this year’s cold storms came in January and February, when snowpack accumulation was even greater. Blizzards closed mountain highways, ski resorts were at times forced to close, and hurricane-force winds were recorded.
“The storm track shifted away from California during March, but we still have a very substantial snowpack, particularly in the higher elevations in the central and southern Sierra,” said Frank Gehrke, chief of the snow survey program for the Department of Water Resources, who led the survey in Phillips Station as flurries came down.
The site along Highway 50 near the Sierra-at-Tahoe ski resort is one of hundreds of places the state surveys throughout the winter. The electronic readings come from 95 points.
While Gov. Jerry Brown has not rescinded a statewide emergency drought declaration issued in January 2014, which ushered in the unprecedented period of water rationing, his office has said it will probably drop the order if the spring snow measurements run high.
“We’ve spent a lot of time at the low end of the distribution, so it’s nice to get one back on the other end.” Mike Anderson, California Department of Water Resources