How road salt contaminates our water supply

Road salt helps protect pedestrians, bikers, and drivers by lowering the freezing point of water, which prevents ice from forming. The use of salt is widespread, with Chicago alone using at least 320,000 tons of salt one winter to control ice on roads, parking lots, and sidewalks.

But excessive use pollutes our drinking water. Fears of lawsuits and little information on responsible salt practices incentivize municipalities and businesses to use more salt than they need on parking lots and sidewalks.

Road salt doesn’t just disappear — it enters bodies of water and accumulates over time, which impacts aquatic life and pollutes drinking water. Unlike sediments and nutrients, salt cannot be easily treated or filtered out of water. While it is not toxic, at high concentrations, the salt can be tasted in the water. Salt concentrations in groundwater have been rapidly rising across the Chicago region since the 1960s, when road salt became common place.

Snow falling on train station. Metra train on tracks, Pace bus at bus stop. Truck with snow plow attachment.

To maintain our region’s water quality and supply, we need to improve how we salt everywhere, from public roads to private parking lots. The Northwest Water Planning Alliance (NWPA) and the Conservation Foundation (TCF) are working to help municipalities, private contractors, and homeowners reduce road salt use.

NWPA recognizes the need to update salting practices on private parking lots and sidewalks. Building on work initiated by NWPA, TCF developed the Winter Maintenance Manual for Parking Lots and Sidewalks. This fall, they also established a training and certification program — Salt Smart Certified — for contractors, business owners, park districts, municipalities, school districts, and libraries.

Many road and stormwater departments across the region have already started implementing better salting practices. For example, the McHenry County Division of Transportation uses trucks with a computerized dispensing system, which places the optimal amount for the surface. They also use different techniques and materials, such as a salt brine, to reduce the needed salt amount and minimize salt from scattering.

With more information on and support for salting best practices, northeastern Illinois can ensure we stay safe in the winter, without compromising the quality of the region’s waters. The Salt Smart Collaborative offers tips and resources for how to salt responsibly for residents, public agencies, and private contractors. It includes guidance for which materials to use, and how much, depending on the temperature.

Learn more about salting responsibly from the Salt Smart Collaborative.