California’s snowpack is supposed to reach its peak April 1, but when state surveyors went out Wednesday for their final snow survey of the year near Lake Tahoe, they found only some sparse patches of snow on the bare grass.
“We’re calling today’s measurement zero,” said Andy Reising, manager of snow surveys for the California Department of Water Resources. “It came off really fast.”
Snow across California’s Sierra Nevada is at just 18% of average — the second smallest since 1950. A month of record-shattering heat thawed the snow and sent runoff coursing into streams and rivers, leaving only minimal water in the mountains as the state heads into dry season.
Scientists say this is exactly what climate change looks like, and it’s compounding the water problems of California and other Western states. The early melt reflects a long-term pattern that is becoming more pronounced as temperatures rise.
“This particular year is as clear an indication of the influence of climate change as anything we’ve seen,” said Peter Gleick, a leading water scientist and co-founder of the Pacific Institute. “Climate change is influencing California’s water system quickly and severely.”
This year the Sierra snowpack peaked on Feb. 25. It was only 73% of average, then rapidly dwindled from there.
The summerlike heat in March broke monthly records in many areas of the Western United States. Daniel Swain, a climate scientist with UC Agriculture and Natural Resources, described it as one of the most “extreme heat events ever observed in the American Southwest.”
Light snow covers the meadow where the California Department of Water Resources conducted the April 1 snow survey at Phillips Station in the Sierra Nevada.
(Nick Shockey / Calif. Dept. of Water Resources)
The warmth and premature melt mean the state’s forests will dry out a month earlier than usual, or even more, Gleick said, which increases the risk of wildfires.
“It could be a very bad fire year,” he said. “It also means rivers and streams are going to dry out sooner, and that has bad implications for natural ecosystems and our fisheries.”
Cities and farms will probably still have ample water because major reservoirs in Northern California are nearly full. That’s because this winter brought decent rain and the three years prior were wet, too.
“We were lucky this year in the sense that even though we have so little snow left, we had an average amount of rainfall,” Gleick said. “There are going to be years, inevitably, where we not only have almost no snow, but we don’t get the rain either.”
California’s smallest snowpack on record was in 2015, just 5% of average.
Small blades of natural grasses poke through light snow on the meadow at Phillips Station in the Sierra Nevada.
(Andrew Nixon / California Department of Water Resources)
This week, a storm arrived in the Sierra Nevada after weeks of sunny dryness. As state water managers held their survey on the meadow, a light snow fell — probably some of the last the state will see until late fall.
Karla Nemeth, director of the California Department of Water Resources, said the minimal snow and high temperatures “are setting us up for what will be a challenging year for water management in the state.”
“What we have in our reservoirs in California is all we’re going to get,” Nemeth said. So it means every Californian needs to use water as carefully as they can.”
The rapid loss of snow is also affecting the Colorado River, another major water source for Southern California, which has shrunk during a megadrought worsened by rising temperatures. The snowpack in the upper part of the Colorado River watershed is now just 23% of average.
Though California isn’t in a drought, abnormally dry conditions have spread and now cover about one-fourth of it, largely in the northeast, according to the U.S. Drought Monitor website.
California traditionally has relied on the Sierra snowpack to store about 30% of its water.
“We’re losing that storage,” Gleick said. “If we can’t depend on reliable long-term snowpack and snowmelt later in the year, we’re going to have to do other things to make our water system more resilient.”
When Gleick wrote his dissertation at UC Berkeley in the 1980s, he analyzed a range of climate scenarios and how rising temperatures would change the timing of runoff in Northern California.
“Current trends precisely match scientific projections from decades ago,” he said. “More and more of our annual runoff is occurring in the winter months, and that’s because it’s more rain, less snow and faster snow melt.”
Adapting to these changes requires new thinking and new approaches, he said, including efforts to use water more efficiently, recycle more wastewater, capture more runoff to replenish groundwater, and change how reservoirs are operated.
Gov. Gavin Newsom and his administration are also supporting plans for new water infrastructure projects including Sites Reservoir northwest of Sacramento and a 45-mile water tunnel beneath the Sacramento-San Joaquin River Delta.
As climate change brings shortened and wetter winters, Nemeth said, the state needs to “retrofit our infrastructure to deal with this new pattern.”
