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Where does stormwater go in winter?

| November 22, 2020 1:10 AM

As the last leaves fall and days grow shorter, we all get ready for a winter of snow. This is a particularly big topic for the city of Coeur d’Alene and local highway districts as they prepare to plow snow, stockpile it, and distribute brine and sand for traction on streets.

You may not think much about stormwater when you’re driving through the wintery weather, but snow is precipitation which becomes stormwater to be managed. Plowed snow can contain pollutants such as salt, sand, oil, grease, heavy metals and trash, which can accumulate in areas where snow is stored and can be released when snow melts.

Disposal of snow directly into streams, rivers and lakes is not allowed. In and around Coeur d’Alene, though, stormwater from snow, as well as pollutants it may carry from streets and parking lots, can eventually make its way into groundwater, Coeur d’Alene Lake and the Spokane River.

Managing snow the right way to protect these water resources is a goal of the city of Coeur d’Alene, Post Falls Highway District, Worley Highway District, East Side Highway District and Lakes Highway District, who work together to maintain roads in our area. Through proper snow storage and responsible use of brine and sand, these water resources can be protected while assuring public safety. The challenge comes in finding a balance between safety, cost and environmental impacts.

In most winter seasons, the city can accommodate snow storage within the right-of-way and in the corners of parking lots. However, in years with greater snowfall, snowbanks become too large and some snow must be removed to other locations. Vacant city- or county-owned properties have been used for snow storage in the past as long as they are not near lakes, streams or stormwater facilities.

In addition to plowing, the city and highway districts distribute brine and sand for traction at priority locations, such as areas where emergency vehicles operate, steep hills and curves, and intersections with stop signs and lights. The city purchased over 500 tons of sand in 2019. Coeur d'Alene operates its own De-icing Solution Center, which allows the city to mix de-icing products as needed, based on conditions. The street department uses an average of about 75 tons of salt each year. One ton of salt makes about 900 gallons of de-icing solution.

The first snows each year generate a lot of discussion on snow plowing and management. More information may be found at cdaid.org/snow. Guidance for cities to minimize the environmental impact from snow disposal are also available: https://denr.sd.gov/dfta/wp/snow.aspx. To find other Our Gem articles on Coeur d’Alene’s stormwater, visit uidaho.edu/OurGem.

Here are a few things city staff ask citizens to do in order to help the snow management process run smoothly:

• Don’t push or blow snow into the right-of-way. It’s illegal and a hazard.

• Park in your driveway if possible.

• Clear snow around fire hydrants and catch basins to allow access and prevent flooding.

• Shovel your sidewalk to give pedestrians a safer place to walk.

• Pick up your dog’s waste when out on walks. Just because you can’t see it under the snow doesn’t mean it goes away.

• Please remember, it drains to the lake.

The Our Gem Coeur d’Alene Lake Collaborative is a team of committed and passionate professionals working to preserve lake health and protect water quality by promoting community awareness of local water resources through education, outreach and stewardship. Our Gem includes local experts from the University of Idaho Community Water Resource Center, Coeur d’Alene Tribe Lake Management Department, Idaho Department of Environmental Quality, Kootenai County, Kootenai Environmental Alliance, Coeur d’Alene Regional Chamber and CDA 2030.