While shredding Utah’s ski slopes last year, McKenzie Skiles noticed something peculiar: The snow seemed a lot dirtier than normal.
Skiles, a snow hydrologist at the University of Utah, did what any good scientist would do in response: She set up an experiment to figure out why.
Now, she and her colleagues report that her hunch turned out to be right: Snow in Utah’s Wasatch Mountains east of Salt Lake City was dustier in 2022 than in any winter since scientists began keeping track in 2009, according to their new paper published in June in the journal Environmental Research Letters. So much dust coated the region’s famed powder—nicknamed “the greatest snow on earth”—that it melted 17 days earlier than it would have without any dust, per the study.
Earlier and faster snowmelt is an issue for several reasons. It makes ski season shorter for the state’s many popular resorts, which collectively helped infuse more than $2.35 billion in direct visitor spending into the local economy during the 2021-22 season. It also can overwhelm the state’s water infrastructure, which is set up for a slow and steady trickle of snowmelt, not a rapid influx. Another ripple effect: With the ground snow-free earlier in the season, that makes the surrounding forests drier—and perhaps more vulnerable to wildfires.
The disappearing Great Salt Lake is at least partially to blame for these trends. The saline lake is drying up, in part because of human water consumption, which means more dry lakebed is exposed to the air. When the wind blows, it carries dust from the lakebed up into the mountains and deposits it atop the snow. This dust layer absorbs more sunlight than pure, white snow does, causing the powder to melt more quickly. (The dust is also polluting the air and may raise residents’ risk of respiratory issues.)
“We’ve known in the past that we’re getting dust from the dry lakebed,” says Skiles to the Salt Lake Tribune’s Leia Larsen. “But I didn’t necessarily think it would be as important of a dust source as it was.”
To better understand the situation, Skiles and her colleagues took samples of snow from an area near Alta Ski Resort, located just east of Salt Lake City in a popular skiing region called Little Cottonwood Canyon.
Using information from storms that hit that winter, including atmospheric conditions and wind direction, they determined where the dust came from. A desolate, arid region known as the West Desert, situated west of Salt Lake City, contributed roughly half of the dust, while the Great Salt Lake’s dry beds deposited nearly a quarter of it. Other deserts and lakebeds in the West were responsible for the remainder of the dust.
Now, Utah appears to be locked in a vicious cycle: When the snow melts earlier in the spring, that means the landscape dries out more quickly during the heat of the summer. That drier landscape, in turn, then contributes more dust to the snow, making it melt even faster.
The shrinking size of the Great Salt Lake also affects this feedback loop, because evaporation from its waters typically helps create as much as 10 percent of the snow that falls on the Wasatch Mountains. A smaller lake means less snow, which means less snowmelt—and the cycle may repeat itself until “it’s very possible that we lose the lake altogether,” as Patrick Belmont, a hydrologist at Utah State University who was not involved in the new research, tells Science News’ Brianna Randall.
“The future of Utah is going to be drier,” he says to the publication.
More broadly, the findings are important because current snowmelt forecasting tools don’t factor in the effects of dust. This means the many Utah communities that rely on snowmelt for water may be consuming the precious resource inefficiently, based on imprecise forecasts. But the new data may be able to help fine-tune those predictions.
“If it is a big dust year, it has a really dramatic impact on water resources,” Skiles tells Deseret News’ Amy Joi O’Donoghue.