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If You Use Road Salt, Use Less
First and foremost, you probably are using WAY too much road salt to melt the snow and ice effectively. Instead of trying to form a solid barrier of salt on your driveway, aim for a scatter pattern wherein the individual salt grains are about 3 inches apart. The Minnesota Pollution Control Agency recommends using about one coffee mug full of salt (roughly 12 ounces) for melting either a 20-foot driveway or ten sidewalk squares (approximately 1,000 square feet).
When purchasing deicing salts, look for products made from magnesium chloride as these will release far less chloride into the environment. Also, take time to clean up excess road salt before rains begin or when rising temperatures lead to high amounts of snow runoff. You should avoid deicing agents that include nitrates or ammonium sulfate. Not only can these chemical compounds damage the concrete of your driveway, but they can even further cause ecological damage once they are washed into the watershed.
Road Salt Environmental Impact Studies
One recent study, Salting our Freshwater Lakes, found an increase in chloride concentrations in one-third of the 371 studied in the northern United States and southern Canada lakes. Several of those lakes showed chloride concentrations that were close to levels that could harm aquatic life. The study believed that the widespread use of deicing agents during the winter was the primary cause.
A 2008 study estimated that 30 percent of the salt applied to the Twin Cities Metropolitan Area roads ends up in the Mississippi River. The salt that is not washed into the Mississippi River most likely filters into groundwater or contaminates soil, lakes, and wetlands, thus contributing to the loss of habitat for several freshwater aquatic species.
Excessive amounts of chloride in groundwater sources can present a public health concern. A 1993 study found that 55 percent of salt applied to a catchment in Toronto is stored in subsurface water.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.