Are Rock Salt and Deicing Agents Bad for the Environment?

It seems to happen every year, no matter how much you try to avoid it. After sleeping through your 6:00 AM alarm, you wake up late, throw together a quick breakfast, and rush out to your car. About halfway down your driveway, however, your shoes catch that patch of ice that formed overnight due to below zero temperatures, and you end up falling and potentially injuring yourself. While some of us might be able to laugh off that unexpected slip, not everyone is so lucky. Around one million Americans are injured due to slip and fall injuries annually. In 2014 alone, over 42,000 workplace injuries or illnesses resulted from slips from ice, sleet, or snow. Protecting yourself and others from a dangerous fall is a high priority for all homeowners; road salts also come with several environmental drawbacks, which we will detail below. 

Deicing agents, and especially sodium chloride and calcium chloride, obviously contain chloride. While this chemical property helps these products melt ice and snow, once snow or ice melts or a winter rainstorm occurs, the chloride ends up getting washed into our watersheds. For homeowners who enjoy the challenge of maintaining a beautiful lawn or garden, salts in deicing agents can also contaminate topsoil, leading to increased alkalinity and reduced fertility. Large amounts of salt in topsoil also reduces the soil’s natural ability to retain water, meaning that your yard will have increased irrigation requirements.

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).

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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.

The Best Alternatives to Road Salt and Deicing Agents

While small amounts of road salt or deicing agents may be necessary after a winter storm, there are ways to reduce our reliance on them. The reduced use of road salt and deicing agents will also help to reduce adverse environmental effects.

Hire Neighborhood Kids to Clear Your Driveway

Of course, the more snow and ice you remove manually, the less deicing agent you will need. If you cannot find your snow shovel, consider hiring local kids who are enjoying their snow day to come and clear off your driveway or sidewalk.

The State of Wisconsin Uses Cheese Brine

For people who are looking for a sustainable alternative, the state of Wisconsin has recently begun experimenting with cheese brine as a more environmentally friendly deicing agent for state roads. The cheese industry of Wisconsin has to discard hundreds of thousands of gallons of cheese brine each year (a byproduct of making cheese). However, the brine will not freeze until at least 15 below zero, making it an excellent alternative for keeping roads clear of ice. While there are still no cheese brine deicing agents commercially available, they might become available in the coming years.

Driveway Sand Instead of Salt

Sand is also another alternative that won’t melt away the ice but will provide some traction for your boots. Keep in mind that while sand will help with traction, it does involve some light cleanup come springtime.

Hiring certified winter maintenance professionals is one strategy to help you minimize your reliance on deicing agents. These professionals know of techniques to keep your patio, sidewalks, and driveway safe and free of ice with only a minimum usage of deicing agents.

Article by:

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.