Researchers at the University of Utah recently published a first-of-its-kind study that measures the impact dust has on melting snow in the Colorado River basin.
Dust has long been credited to accelerating snowmelt in the Intermountain West. Blowing from arid regions and settling in the mountains, the dust darkens the snow, lowering its albedo — essentially, darker snow doesn’t reflect the sunlight as well, leading to more heat absorption and speeding up the melting process.
It’s particularly prevalent in the Colorado River basin, with large mountain ranges like the San Juans, La Sals and Maroon Bells pushed up against dry expanses of desert. As drought continues to impact the region, dust events have worsened, depleting the snowpack at faster rates and complicating an already precarious situation for the Colorado River and the 40 million people who get their drinking water from it.
And while previous papers have recorded the impact dust has on snowmelt, University of Utah researchers are the first to study an area as large as the Colorado River headwaters, which spans multiple states. According to the university, there are no snowmelt models — streamflow forecasts in mountain basins essential for areas that rely on snowpack for water — that take dust into account.
“The degree of darkening caused by dust has been related to water forecasting errors. The water comes earlier than expected, and this can have real world impacts — for example if the ground is still frozen it’s too early for farmers to use. A reservoir manager can store early snowmelt, but they need the information to plan for that,” said McKenzie Skiles, associate professor at the university’s School of Environment, Society and Sustainability. “If we can start to build dust into the snowmelt forecast models, it will make water management decision-making more informed.”
Stiles is a co-lead author of the study, which was published in the scientific journal Geophysical Research Letters in March.
Stiles and other researchers analyzed 23 years of satellite images, from 2021 to 2023, to observe snow darkened by dust in the spring months. They found that dust accelerated snowmelt in the Colorado River Basin every spring, even during less-dusty years.
During runoff season, typically between April and May, the snowpack melts about 10 to 15 millimeters each day. According to the study, dust deposition can accelerate snowmelt by 1 millimeter per hour during peak sunlight — during a “high-dust” year, that can factor out to about 10 extra millimeters each day.
“It’s not just how much dust gets deposited over a season, but also the timing of dust deposition that matters,” said Patrick Naple, doctoral candidate of geography at the University of Utah and lead author of the study. “Dust is very effective at speeding up melt because it’s most frequently deposited in the spring when days are getting longer and the sun more intense. Even an extra millimeter per hour can make the snowpack disappear several weeks earlier than without dust deposition.”
One of the most comprehensive analyses of dust and snowmelt yet, the university says this research could improve water forecasting and allocation for communities that rely on the Colorado River.
