March 3, 2011
Melting snow can be a major contributor to pollution of West Michigan lakes and rivers during the early spring months. Snowmelt, just like rain, is a component of stormwater runoff. It carries pollutants from roads, highways, parking lots, and bridges to local waterways via municipal stormwater systems and surface runoff. Snowmelt can also be a significant cause of sedimentation and erosion.
“The environmental impact of snowmelt is very similar to that of runoff caused by rain events, and in some ways, the impact of snowmelt can be even more extreme than rain.” said Kristi Klomp, Water Programs Manager for the West Michigan Environmental Action Council. “It’s the same basic principle: The melted water serves as a vehicle for pollutants to reach our lakes and rivers. However, snowmelt has the potential to introduce contaminated runoff to our waterways at a more rapid rate than rain events, simply because the ground is frozen, and functions as an impervious surface with little chance of infiltration, much like our streets and roads.”
Klomp explained that snowmelt introduces most of the same pollutants to waterways as would stormwater runoff, such as dirt, dust, metal and rubber deposits, antifreeze, engine oil, pesticides, fertilizers, pet waste and litter. These pollutants degrade water quality, harming human and aquatic life.
“You can see the most obvious contamination as the snow banks recede,” Klomp said. “There is always dirt and trash left behind.”
Deicing salt used on roads, driveways and sidewalks is an additional concern. Snowmelt runoff containing road salt squelches roadside vegetation and can produce high sodium and chloride concentrations in ponds, lakes, and rivers, creating toxic conditions that threaten aquatic life. Klomp recommends the use of less harmful alternatives to road salt such as calcium magnesium acetate or products with reduced chloride content, such as those made from agricultural by-products.
To mitigate the larger impacts of stormwater runoff, Klomp suggests the use of low impact development strategies such as rain gardens or pervious pavement that will keep snowmelt on site, allowing pollutants to filter naturally into soil rather than washing into lakes, rivers, and streams.
Klomp said that some fairly simple behavior changes could also have very meaningful impact. “With snow we have a good deal of control on whether or not it melts on an impermeable surface. By strategically depositing snow on a level surface of lawn, field or grassy area, you can dramatically reduce runoff.”