Winter Stormwater: Snowmelt and Solutions

It’s been a cold and snowy winter in the Lake Champlain basin: Burlington, Vermont has received over 50 inches of snow from November 2025 through January 2026, and on February 13, 2026, Lake Champlain was officially deemed “iced over” for the first time since 2019. Winter may seem to have a steady grip on our region, but the successively longer days of March are setting the stage for a seasonal change. Every extra minute of sunlight encourages the snowy mountaintops and icy riverbanks to melt. Snowmelt flows over and through the landscape as runoff, and as that runoff travels through the watershed, it carries a footprint of the land into our waterways and ultimately to Lake Champlain. 

The types of pollutants transported by stormwater will depend on what is on the land: in agricultural areas, it may consist of more pesticides and animal waste, while in urban areas, it may consist of road salt, heavy metals, and car fluids. Eroded sediment high in nitrogen and phosphorus is carried from both types of land use. After a consistently frigid winter with few periods of thaw, many of these pollutants have been locked in frozen terrain. 

The cold temperatures we’ve experienced this winter depart from the pattern of winter warming we’ve seen for the past few decades—a trend expected to continue with climate change. Warmer winters mean longer, more frequent, and sometimes more intense periods of rain, rain-on-snow, and wintertime snowmelt. According to research from the University of Vermont, this means that more nutrients are carried into the lake by stormwater during the cold months than previously thought. Preliminary data indicates that 15 to 55 percent of the phosphorus delivered over the course of the year is conveyed in the winter, a season once believed to be essentially inactive for stormwater runoff.

Snowmelt is a highly visible source of polluted stormwater runoff, particularly in urban areas. Piles of snow darkened by dirty car tires and nutrient-laden sediment melt and dissolve the mounds of salt that have accumulated on roads and sidewalks. The result is messy, both aesthetically and in terms of water quality. Stormwater in urban areas is a concern because of the prevalence of impervious surfaces—spaces like paved roads, shingle roofs, and concrete sidewalks that prevent stormwater from infiltrating into the ground. In areas with a lot of impervious surfaces, stormwater runoff will reach surface waters more quickly and in higher volumes than in areas with more space for infiltration.

One way that more urbanized areas in the Lake Champlain Basin seek to address this problem is with green stormwater infrastructure (GSI). GSI is an approach to stormwater management that seeks to mimic the natural water cycle and slow the flow of runoff by capturing, absorbing, and filtering it. This approach includes practices such as rain gardens, permeable pavement, rain barrels, constructed wetlands, green roofs, and bioswales. These practices use plant and soil systems, permeable surfaces, stormwater harvesting and reuse, or landscaping to store, infiltrate, or evapotranspirate stormwater to reduce runoff.