With winter having come to a close, people living near the Rocky Mountains will have to reckon with the effects of snow contamination, an enduring issue magnified by mining activities in the region. A new study provides an unprecedented look at the heightened levels of contaminants that have been carried to the Rockies by winter storms.
The study, recently published in the journal Environmental Pollution, has pinpointed mining operations in the Pacific Northwest as the source of contaminants. Mercury and other metals from these mines have been infused into snow that accumulates in the northern range of the Rockies. Since the western U.S. heavily relies on mountain snowpacks for water, increased snow contamination could entail dire consequences in the near future.
The Significance of Snowpack
Iconic winter pastimes in the western U.S., like skiing and snowboarding, wouldn’t be possible without mountain snowpack, which builds up and eventually melts by spring and summer. But the importance of snowpack extends beyond recreation, as it provides the region with water for hydropower, agriculture, and household use for millions of Americans.
Snow contamination in the northern Rockies now threatens this vital component of the water cycle. The new study found that higher levels of metal contaminants — Mercury, Zinc, Cadmium, and Antimony — now plague the mountains’ snowpack.
Read More: Snowpack in the West Is Not Looking Good Right Now
An Increase in Contamination
During the spring of 2018, researchers collected snow samples from 48 different sites throughout the Rockies and measured metal concentrations in each one. This not only included metals from mining but also metals like calcium that come from natural dust.
The researchers compared the portion of metals that only came from natural dust to those that came from both dust and mining activities. They also looked at data from the National Atmospheric Deposition Program, which measured mercury and calcium in precipitation from 2009 to 2018. The results showed significant metal contamination in the northern Rockies, spanning across Montana, Idaho, and northern Wyoming.
“The snow samples showed us that contamination is higher in the northern Rockies, and that was really interesting,” said Monica Arienzo, a hydrologist with the Desert Research Institute, in a statement. “Looking at mercury contamination over time helped us say that 2018 is not just a fluke. When you start to see these trends that are consistent between different records, it makes you feel more confident that something’s really happening here.”
While contamination levels were within the EPA’s guidelines for drinking water and aquatic life, the contaminants can cause the snowpack to reflect less sunlight and melt faster.
Surging Snowpack Problems
The researchers tracked down the probable source of the contaminants by following previous winter storms and referencing a USGS dataset with information on mining and smelting locations.
According to the study, the northern Rockies received many storms that moved in from the Pacific Northwest, while the southern Rockies received storms that moved across the Mojave Desert. The contaminants examined by researchers likely originated from mining sites near the northern Rockies and were transported by the storms.
“Our idea is that the dust from current and historical mining sites gets carried up into the mountains and deposited across our study sites,” said Arienzo in a statement. “This study shows the importance of continued scientific monitoring efforts, like the long-term USGS datasets we used here, as well as mitigation of current and historical mining sites.”
Future studies by the research team will survey mercury levels in tree rings and compare them to mercury levels in the snowpack to determine how the metal spreads throughout the environment.
The West faces an uncertain future with regard to its snowpack, which has been declining year after year in some regions. Earlier snowpack melt, along with an increase in rainfall, could start to impact water availability and cause potential snow droughts, possibly warranting a revamping of water management strategies in the coming years.
Read More: Lake Mead Water Levels Drop Again as Snow Drought Takes Over Western U.S.
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Environmental Pollution. Latitudinal gradients of snow contamination in the Rocky Mountains associated with anthropogenic sources
National Environmental Education Foundation. The American West's Disappearing Winter Snowpack
Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine
