Californians may collectively be breathing a sigh of relief, but not elation, this week, after the state’s latest snowpack reading. A wet and cold March saved California from a near record-low snowpack, but it proved too little too late to bring a full recovery. And worse, climate scientists say we should start getting used to these low snowpack years.
How much water content the snow holds in the Sierra Nevada mountains is crucial to the state’s water supply, and snowpack readings at the start of April – usually the peak accumulation of the season – are a key indicator of the winter’s bounty (or lack of).
As of April 3, the snow-water equivalent (how much water content is in the snow), was 52 percent of the long-term average statewide. And in the northern part of the Sierra Nevada, which drains into the state’s two biggest reservoirs, it was only 41 percent of average.
It’s not great, but it’s a vast improvement from the outlook just over a month ago when the snowpack was near the lowest recorded. “At the end of February things were not looking so great, things were extremely dry throughout the state,” said Daniel Swain, a climate scientist at University of California, Los Angeles’ Center for Climate Science. “The whole winter had been very warm, in some place the warmest on record.”
Swain called California’s winter “really weird” this year, with heat waves and fire danger that lasted through December. “The Thomas Fire, California’s largest fire in modern history, occurred in mid-December, which is kind of mind-boggling,” he said. Typically, California’s wet weather returns in October or November, stamping out fire risk.
Other than the storms that brought fatal flooding and mudslides to Santa Barbara County in January, the winter in Southern California was nearly bone dry until the end of February.
March, Swain said, was a reversal of fortune, with wet weather returning and being accompanied by much colder temperatures, an ideal combination for boosting mountain snowpack. “We actually had a below-average month temperature-wise in most of the state, which hasn’t happened in some places in a long time,” he said. “And that combined with a pretty active storm track meant we got a lot of snow in the mountains over a three- or four-week period.”
Sierra Nevada snowpack nearly tripled during March.
The other good piece of news is that 2017 was a huge water year for California, and the state’s major reservoirs are at 107 percent of average for this time of year, according to the Department of Water Resources. But this also means that California will be working its way through some of its reserves this year as it taps the “bank account” of water supply in reservoirs. And so far, contractors that receive water via the State Water Project are projected to receive only 20 percent of their allocation, although that figure may be amended.
At a manual snowpack reading at Phillips Stations in the Sierra Nevada on April 2, Department of Water Resources director Karla Nemeth used the opportunity to pitch for smarter and more efficient use of water. “We need every Californian to conserve,” she said. After learning to cut back during lean years, recent figures have shown that Californians are nearly back to using as much water as they were before the state’s recent drought.
David Rizzardo, chief of Snow Surveys Section and Water Supply Forecasting at the Department of Water Resources, said the full reservoirs mean there’s “no immediate concern” regarding water supply but there could be “potential impacts should we have a second dry year in a row next winter.”
And another dry year, or at least a year with low snowpack, is a legitimate concern, officials say.
Maggie Macias, an information officer at the Department of Water Resources, said the biggest factor this year in California was a lack of storms, especially during December and February, which are historically the two wettest months. “When we did get storms, most notably those in January and again in March, some were of a warmer, atmospheric river nature, which tends to produce more precipitation as rain rather than snow,” she said. “So warmer storms/temperatures did play their part this year.”
This, she said, is a noticeable trend over the past few years. “We’ve set some high temperature marks month to month or over seasons that are worrisome,” she added.
In recent years, Swain said the overall trend has been a lagging snowpack, even in years when there’s adequate precipitation. And higher temperatures are to blame there. “That’s sort of the warming signal that’s buried in everything now,” he said.
California will still experience wet years and occasional big snow years, he said, but they will become less frequent and less big. A report just published by the UCLA Center for Climate Science found that if nothing is done to curb climate change, Sierra Nevada average spring snowpack is likely to drop by 64 percent by the end of the century and by 30 percent if some efforts are made at reducing greenhouse gas emissions.
But warming impacts are already being seen.
“There has been an expectation for a long time that we would see Sierra Nevada snow lines, the elevation of where the mean snow is falling, creeping up the mountain and we’d see less snow at lower and middle elevations, and then eventually the overall snowpack would start to decrease,” Swain said. “And based on a couple of studies that have come out in the last six months – we’re there. It’s no longer ‘we expect to see,’ it’s ‘we are starting to see this in the real world.’”