Old snow crunched underfoot in mid-January as a dozen people snowshoed near Molas Pass in Colorado’s San Juan Mountains. The interpretive hike, hosted by local environmental organizations, covered ecology, climate change and snow. It was the perfect classroom: below an azure sky, bare ground beneath trailside spruces and pines was a local example of what turned out to be a devastating lack of snow across the West.
Mountain snowpack is the West’s largest reservoir, providing water for 100 million people and diverse ecosystems. The amount of water stored in the snowpack historically peaks around April 1. But this year, the snowpack in many places was absent, or nearly so, by then — the lowest level in the 45 years since automated measurements began.
A stubborn high-pressure ridge contributed to the snow drought by shunting winter storms north to Canada in January. But the main culprit, according to the nonprofit Climate Central, was exceptional heat from climate change, which also caused a spring heat wave that decimated what snow there was at a time when other dry winters have seen “miracle March” snowstorms.
The lack of snow was unusually widespread across the Western U.S. But considering it as a whole makes it easier to miss the regional manifestations and implications of a winter that also brought record flooding and record dryness in addition to record heat. Here’s how the snow drought played out in a few regions that exemplify this winter’s variability:
Whiplash in Washington’s Cascades
Winter in Washington’s Cascade Range started and ended in “wet” snow drought — with precipitation falling as rain instead of snow. In December, over 2 feet of rain fell in two weeks in some places, melting much of the nascent snowpack and causing catastrophic flooding west of the Cascades. But it also replenished reservoirs in the Yakima Basin, on the drier eastern side of the range, which were only 8% full in October, a quarter of their normal volume.
Dry snow drought hit in January, when little precipitation fell. While pockets of Washington’s Cascades saw near-normal precipitation in February, most of the mountains stayed dry, and the range’s snowpack remained well below average. Then, despite several feet of snow landing in March, rain followed and washed it away.
That’s a problem for the Yakima Basin, which lacks the reservoir capacity to store enough runoff to meet the region’s needs. The snowpack typically serves as an additional reservoir, storing water as snow into summer, said hydrogeologist and geochemist Carey Gazis of Central Washington University in Ellensburg.
South of Ellensburg lies the Yakima Valley — the “fruit bowl of the nation” — where snowmelt is essential for irrigating crops, including cherries, apples, grapes, hops and mint. It also supports the Yakama Nation’s efforts to restore populations of culturally important migratory fish. As of March, the Bureau of Reclamation forecasted that many farmers in the Yakima Valley would receive just 44% of their usual water supply this growing season due to the snow drought.
One long-term solution is to create more water storage by augmenting aquifers. “There’s all this space under the surface that can hold more water,” said Gazis, who studies such processes. Projects pumping runoff or enhancing passive water infiltration into the ground are already happening in parts of the basin, including on the Yakama Nation reservation.
Northern Rocky Mountain high (-elevation snowpack)
As in Washington’s Cascades, winter in the Rocky Mountains of Idaho, Montana and western Wyoming was bookended by wet snow droughts, with a dry January in between. However, colder temperatures at higher elevations allowed for a near- to above-average snowpack in some areas that persisted into mid-March, leaving them in better shape than most of the West in early April.
That helped places dependent on winter tourism, such as Idaho’s Wood River Valley. “It’s as busy as ever, if not a little busier, because we have snow,” unlike many other winter destinations, such as those in Colorado, said the director of the valley’s Environmental Resource Center, Ashton Wilson, in February.
Additionally, Russell Qualls, Idaho’s state climatologist, speculated that the Wood River Basin and others nearby may do “fairly well” this summer in terms of providing water for the towns and agriculture that depend on them.
But little to no snow at middle and lower elevations in Idaho, Wyoming and Montana — and ongoing unseasonable heat — might mean a long fire season unless sufficient rain arrives in spring and summer. Indeed, while fire season usually starts in May or June in Montana and Wyoming, both states experienced wildfires over 1,000 acres in March.
But high and dry in Colorado
Colorado also experienced such medium-sized wildfires, but they started much earlier — in December. Both December and January were abnormally dry, and one of the few storms that did arrive dropped rain at up to 11,000 feet — unusually high for winter, and unprecedented in much of Colorado.
This was evident at the January snowshoe hike near Molas Pass, led by the San Juan Mountains Association and Mountain Studies Institute. Outdoor educator Colin Courtney guided attendees wielding avalanche shovels in digging a snow pit to measure the snowpack’s depth and water content. With a dull thunk, shovel blades hit dirt just 2 feet down. As he melted snow samples over a camp stove, Courtney noted that the snowpack at the pass held 23% as much water as in an average year — the snow water equivalent, a more meaningful measurement than depth alone when planning for annual water needs and wildfire risk. “It’s a very real thing to be concerned this year,” said Courtney.
There are ecological threats, too. Research in New Hampshire and Finland has shown complicated effects on tree health when root systems lack an insulating layer of snow during winter. The impact on trees here — already stressed from the worst megadrought in 1,200 years —isn’t known.
“This is our worst snowpack on record,” wrote climatologist Allie Mazurek of the Colorado Climate Center in an early April email. She blamed the West’s record-breaking March heat wave for tipping the state beyond its prior historic low, in 1981.
Denver has already initiated water restrictions. But the implications go beyond state lines: Colorado’s snowpack also provides water to 18 other states, dozens of tribal nations and parts of Mexico. The Colorado River Basin provides drinking water for one in 10 people in the U.S., irrigates over 5 million acres of cropland and generates substantial hydroelectric power. This year’s snow drought is exacerbating an already fraught fight among the seven states in the Colorado Basin over how to manage the dwindling river.
“One caveat to some of this is El Niño,” wrote Mazurek. The climate pattern may bring lots of rain to Colorado, and forecasters expect it to develop in early fall. “Still, rain tends to do much less for our water supply than snow,” she added.
And snow is a resource that will likely be in shorter and shorter supply in the years to come in the West, where researchers expect climate change to shrink snow-supplied water by about a quarter by mid-century. Mazurek summed up the region’s predicament succinctly: “We should probably be preparing for less water to be coming down from the mountain snowpack than usual.”
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