Aspen’s roads remain icy and snow-covered this week, despite the city’s round-the-clock efforts to keep them clear.

Environmental concerns over the health of the Roaring Fork River limit the tools available for deicing, creating a delicate balancing act between road safety and ecological preservation.

Unlike cities that rely heavily on rock salt, Aspen uses IceSlicer, a granular chloride blend tested over the past few winters. IceSlicer melts snow efficiently while reducing the need for sand, which can clog waterways and harm aquatic life, according to the city’s streets department.

Even with this alternative, city roads don’t always stay ice-free, particularly in neighborhoods where plow coverage is limited.

The Aspen City Council first directed staffers to study deicing options in 2020, weighing safety against environmental risks.

IceSlicer was chosen for its compatibility with existing plows and endorsement by the Colorado Department of Transportation. It is primarily used on streets with high accident rates and bus routes flagged by the Roaring Fork Transportation Authority (RFTA). Many residential streets, however, remain icy despite continuous plowing efforts.

“My team works day and night to make the traveling corridors safe for all. We have three different shifts, which allows us to have 24/7 coverage,” Aspen Streets Superintendent Daniel Maldonado said. “Each shift is constantly cleaning up snow, whether that be in residential areas or the core.”

Plow drivers have worked without pause since the 36-inch snowstorm during Thanksgiving week, with teams clearing residential streets by day and focusing on the downtown core at night.

“The crew strives to keep the streets clean and clear on all shifts, and we are constantly working on removing piles of snow,” Maldonado said. “We do currently use IceSlicer on all designated bus routes, and this has helped us out in a huge way. When using IceSlicer, it requires less plowing and helps keep the driving lanes free of ice buildup.”

Bus routes are the only streets being treated with IceSlicer. This, however, leaves many of the other roads and side streets that many commuters rely on often covered in snow and ice.

Aspen has also cut back on sand, which was once a staple for winter road maintenance. While effective for traction, sand runoff accumulates in the Roaring Fork River, clouding the water and disrupting aquatic ecosystems. Limiting its use aims to protect water clarity and improve river health.

Still, IceSlicer poses its risks. Chlorides can increase water salinity, which may harm fish and other aquatic life.

Although Colorado regulates chloride levels for drinking water, no formal standard exists for aquatic habitats. The Environmental Protection Agency advises that long-term exposure should not surpass 230 milligrams per liter.

“Protecting the water quality of our rivers is central to the city of Aspen’s commitment to stewardship,” Clean River Program Manager P.J. Murray said. “By reducing the impacts of urbanization, such as minimizing pollutants like deicing agents and providing stormwater runoff treatment, we preserve the natural beauty of our surroundings.”

Murray underscored the importance of this practice for the valley’s ecosystem.

“A healthy river benefits us all,” she said. She said other factors could play into the effectiveness of deicing agents, like IceSlicer, and depend on specific conditions. For instance, IceSlicer works best when applied before snow or ice forms. However, in extreme cold (below minus 10 degrees Fahrenheit) or during refreezing events caused by melting snow turning back into ice overnight, its effectiveness can be reduced.

Murray said that although deicing agents improve roadway safety significantly, they are not a cure-all, and drivers should always remain cautious during winter conditions.

Although no direct correlation between IceSlicer and reduced winter accidents has been confirmed, RFTA drivers have reported safer conditions and greater confidence on icy roads.

Pitkin County uses a combination of sand and IceSlicer on many of its 115 miles of roadway.

“We use a CDOT spec sanding material that has to pass the hardness test, so it doesn’t break down in dust, and about 9% is IceSlicer,” Pitkin County Public Works Director Brian Pettet said. “We primarily use this on county roads where there are hills and curves, where accidents are more likely to occur.” He said CDOT formerly used sand on Colorado 82, and recently switched to magnesium chloride.

“Once CDOT switched to the magnesium chloride, the air quality problem in Aspen went away,” Pettet said. “The air quality problem was directly linked to sand being used in the winter on Highway 82.”