The Damaging Effects of Road Salt

Author: Katie Kaulbach, 281

Date: April 19th, 2021

This winter, Philadelphia has suffered through a very snowy winter. And the snow is accompanied by dangerous ice. Most sidewalk owners put road salt on their sidewalks to avoid being responsible for a pedestrian’s potential injury. Road salt is also used by trucks that clear highways of snow and disperse ice on the roads to prevent car crashes. This ice-melter is crucial to those who are only trying to keep citizens safe. But are the drawbacks of the ice-melter worth the toll the product takes on the environment? Road salt often drains into our water storage and aquatic ecosystems, risking dangerously high salt levels in our water as well as damage to waterlife.

When we disperse salt on our roads, we are unable to collect the salt after the ice has melted. We assume the road salt disappears until we throw more on the ground to re-salt the roads. But the road salt does not actually disappear; it only washes away into waterways and ends up in a pond or lake. If the salt from runoff is trapped in a pond, it settles into layers (Columbia University, How Road Salt Harms the Environment).The layers can withhold oxygen originating at the bottom of the pond from reaching the surface level. As a major source of oxygen for ponds, when these layers form the oxygen content decreases to dangerously low levels (Columbia University, How Road Salt Harms the Environment). This puts many organisms living in the pond at risk because the oxygen they normally get from the water is missing, immediately becoming a major problem for lakes. In a study done by a research team funded by the Global Lake Ecological Observatory Network Fellow Program, it is shown that 7,770 lakes in the North American Lakes Region may be at risk of rising salinity (University of Washington Madison, Road Salt is Making North America’s Freshwater Lakes, Well, Saltier). Lakes that are particularly susceptible are those that have developed land and impervious surfaces around them (University of Washington Madison, Road Salt is Making North America’s Freshwater Lakes, Well, Saltier). The impervious surfaces, like asphalt and concrete, are the surfaces that receive road salt and also do not absorb the runoff to be filtered. These conditions cause the salty runoff to enter directly into the lakes (University of Washington Madison, Road Salt is Making North America’s Freshwater Lakes, Well, Saltier). Similar to the ponds, the salty water forms a dense layer at the bottom of lakes (Adirondack Explorer, Mirror Lake Continues to Have Dissolved Oxygen Issues). This prevents lakes from having their normal turnover, which normally allows for oxygen and nutrients to be equally dispersed throughout the lake (Adirondack Explorer, Mirror Lake Continues to Have Dissolved Oxygen Issues). The lack of normalcy disturbs the ecosystem and all of the organisms living in it. An example of this process can be seen in Mirror Lake, NY, which has received an increased amount of salty water from road salt which has resulted in the lake not having its annual spring turnover for the last two years (Adirondack Explorer, Mirror Lake Continues to Have Dissolved Oxygen Issues). Without the normal dispersal of oxygen, the oxygen and nutrients do not reach the deepest parts of the lake, threatening fish in the lake. For example, this scenario has a profound effect on the Lake Trout species which inhabits the cool oxygenated bottom of the lake during the summer (Adirondack Explorer, Mirror Lake Continues to Have Dissolved Oxygen Issues). As road salt is continually used as the main combatant against ice, the crucial turnovers of lakes will become more inconsistent, putting more species, like the trout, at risk.

Icy sidewalks are a major danger for injuries, but the combatant to this slippery ice is disturbing aquatic ecosystems. So how can we decrease the use of road salt and subsequent salt pollution? A recent invention, a heating pad for melting the ice left on the sidewalk, has begun to solve this issue, but this solution is expensive. For those who cannot afford to pay for a heating pad, there are alternatives to the use of road salt that are effective against fighting slippery ice such as: alfalfa feed, coffee grounds, sand, and clay. The dark particles in these substances create friction between ice and the feet of passersby and their dark colors attract the heat energy of the sun which melts the ice. Another solution is to prevent the snow from turning into ice by attentively shoveling the necessary pathways. These solutions limit the salt pollution in our aquatic landscapes and keep people safe. Ultimately, limiting our use of road salt by using alternatives or shoveling will benefit our aquatic ecosystems and benefit the organisms that inhabit them.