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Study: Great Salt Lake dust causing earlier mountain snowmelt

SHARE Study: Great Salt Lake dust causing earlier mountain snowmelt

SALT LAKE CITY — A new study says dust from the exposed lake bed of the shrinking Great Salt Lake is contributing to an earlier snowmelt along the Wasatch Front.

The University of Utah study published Friday in the journal Environmental Research Letters looked at dust deposition in an alpine area in Alta in the aftermath of a single dust storm in April of 2017.

It was the first ever analysis that measured dust accumulation in concert with snowpack.

Using computer modeling, the study found that dust on snow acts an amplifier of heat by darkening the snow, much like how a black T-shirt worn on a hot day behaves.

The simulation showed that ahead of the storm, dust came from the south, but then shifted to the west. The westerly winds brought dust from "hot spots" in the Great Salt Lake's dry lake bed, a relatively new dust source due to historically low lake levels.

McKenzie Skiles, an assistant professor of geography at the U. and lead author of the study, said the dwindling level of the Great Salt Lake is a concern both for the public health consequences and its impacts on snowmelt.

The study concluded dust accelerated snowmelt by 25 percent.

"What's important about the Great Salt Lake is that there are no water rights, no policy to maintain lake levels. As the lake declines, dust events are projected to become more frequent," she predicted.

"Anything that impacts snowmelt could have economic and hydrologic consequences. And now one of the dust source regions is right next door. Could we do something about it by enacting policy that maintains a minimum lake level?"

The state does have a comprehensive Great Salt Lake Management Plan that addresses management of the lake and its associated resources. It worked for years, too, to develop an integrated model that serves as a foundation for managing future challenges and lake levels.

Joshua Palmer, spokesman for the Utah Division of Water Resources, said there are multiple factors affecting lake levels, including drought, diversions by agriculture, cities and industry and the shallowness of the lake itself.

"It is a very shallow lake and that is a good recipe for evaporation because it heats up and evaporates quickly."

A 2012 study found the lake contributes $1.32 billion in economic input to the state and supports 7,700 jobs.

Four years later, a Utah State University white paper found that the lake had shrunk by 48 percent and its levels diminished by 11 feet since pioneers first arrived in 1847.

"We should all be concerned and engaged in the Great Salt Lake discussion. It is a hugely important part of Utah's economy, our natural environment and it does have an impact on snowpack," Palmer said. "There is more to it than just a lake on the map."

When University of Utah researchers looked at the dust impacts on Alta snow, they found that most of the dust was deposited about an hour after the actual storm passed through, in so-called "post-frontal" winds.

"Sources such as the Great Salt Lake Desert were the largest dust emitters; dust from the dry lake bed hot spots accounted for about 10 percent of deposited dust," a U. statement noted.

Earlier this year, Skiles co-authored a paper that reviewed the literature on the global issue of "light-absorbing particles" on snow.

"Globally, snow is in decline and it's not just from a warming climate—it's more complicated than that — snow is also getting darker," said Skiles. "We know that in some places aerosols are impacting water resources, and it's having this long-term climactic impact. We also know that deposition levels are unlikely to decrease in the future. While we don't yet understand the exact magnitude of impact, we know that dust warrants more attention."

According to Ski Utah, Utah has 13 alpine ski resorts, 10 of which are within an hour of the airport, with 151 ski lifts and 1,353 named runs serving nearly 25,000 skiable acres. Combined, Utah resorts offer 31,000 vertical feet of skiing.

The association says it contributes about $1.29 billion to Utah's economy.

The U. study was co-authored by Derek A. Mallia, A. Gannet Hallar, John C. Lin, Andrew Lambert, Ross Peterson in the U. Department of Atmospheric Sciences and Steven Clark of the U. Department of Geography. Clark also works for the Utah Department of Transportation.