Environmental experts voice concern on road salt pollution in Minnesota waterways as snow melts
Snowmelt season is finally here in Minnesota.
“Those snow piles melt, and they have pollutants in there,” declares Andy Erickson, a storm water expert at the University of Minnesota. “There’s litter, there’s debris, there’s trash. There’s chloride from road salt.”
Erickson, the research manager at the university’s St. Anthony Falls laboratory is carefully watching this weekend’s expected warmup and the runoff from those snow piles.
“When we’re driving in the midst of winter, we’re not thinking about swimming in the summer,” he says. “Put the two pieces together. Think about that balance.”
Erickson and other researchers say their biggest concern is chloride pollution.
“Nothing will remove chloride, which is what we see in the salt,” explains Brooke Asleson, the Chloride Reduction Program Coordinator with the Minnesota Pollution Control Agency.
She says snowmelt runoff into waterways happens every spring, but the last few years have been different.
“We’re seeing more melting and refreezing,” Asleson says. “These are the types of events that have me concerned about the amount of salt being used, to address this, and find that balance of safety and protecting the environment.”
She says in a recent study, U of M researchers – using purchasing records – found about 250,000 tons of road salt are used in the metro every year. The same study back in 2009 found about 365,000 tons were used per year, a drop of 115,000 tons.
Still, Asleson says, when those snow piles begin to melt, much of their contents ends up in waterways.
“They often will run off into our streams, our parking lots, and make their way to a storm drain which will direct them to one of our surface waters,” she notes.
We met Asleson at Thompson Lake in West St. Paul. It’s one of 54 waterways in Minnesota considered by the MPCA, as being ‘impaired’ with his levels of chloride.
“So when we have chloride salt getting into our freshwater, it makes it salty,” Erickson says. “And that can impair all of our freshwater aquatic species. The fish, the plants, all the bugs even, are getting affected by the chloride.”
The agency says impaired waterways can have mercury levels that can lead to limits on fish consumption, impact phosphorus that grows algae, and can make bacteria that makes water unsafe for swimming. However, the MPCA says no chloride-related fish kills have been found.
But, Asleson says the presence of chloride can trigger problems with native fish.
“It can affect their ability to reproduce,” she says. “It can affect the food chain supply because these very small organisms, we call them macro-invertebrates, that will often just die off in high chloride.”
She says the MPCA has connected with government agencies and private companies with an initiative called “Smart Salting” training.
The agency says the training can help entities reduce their salt use by up to 70%.
Asleson says some communities are experimenting with porous blacktop in parking lots, and even heated surfaces on roads and sidewalks.
“If you’ve ever seen, a lot of schools use rotary brooms,” she notes. “Those are really effective at clearing that snow and ice down to bare pavement. You don’t need any chemicals.”
Erickson says he hopes these steps will make a difference.
“We are already seeing some of our groundwater wells tasting salty. We’re already seeing some of our bio-diversity being reduced and being impacted by our salt,” he says. “Five years, ten years, even twenty years from now, if we continue on the trends we’re at, we are going to have saltwater lakes in Minnesota. We could have salty streams in Minnesota.”
Asleson says she’s optimistic that changes are happening with the state’s salt use.
“How can we change how we look at building our streets and our buildings, in a way that facilitates melting naturally, versus putting down a lot of chemicals after the fact,” she notes. “We need some thoughtful planning.”