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Dirty snow could impact spring snowmelt

Dirty snow in the La Sal mountains (Deseret News)

WASATCH VALLEY, Utah– The ugly brown snow that fell over much of Utah last week got everybody’s cars dirty. But it can also have an impact on spring runoff from the Wasatch Mountains. 

McKenzie Skiles, an assistant professor of geography at the University of Utah studies the effects of windblown dust and air pollution on winter snowfall. Dust and soot make the snow darker, so it absorbs more sunlight and melts faster, she explained.

Skiles says windblown dust events tend to happen later in the year, and it’s unusual to have one so early. The dust comes from Western landscapes disturbed by human activity such as grazing and mining and also from the dry shoreline of the Great Salt Lake.

Utah’s polluted urban air also includes black soot that colors the snow, but Skiles noted it’s much less significant than the windblown dust is in affecting spring runoff.

While it’s likely some of last week’s dusty snow will be covered by white snow later in the winter, Skiles says the brown layer can still have an effect. “Later in the season, it will actually re-emerge. That dust doesn’t get carried away in the meltwater as the snow starts to melt,” she said regarding the dirty snow. 

Hydrologists say much of Utah’s spring runoff this year could soak into the soil rather than filling the state’s reservoirs because the past year has been so dry.

Related: Dry weather impacting snowpack in Utah, meteorologists say