Road salt is an invaluable commodity in the winter months, making it easier and safer to drive and walk after it snows. However, new research shows that the use of road salt during this season directly leads to groundwater contamination.
Contaminants contained in road salt enter water sources through storm drains, via surface runoff, and by seepage into groundwater. The high concentrations of chloride entering streams can change a water body's ecosystem, adversely effecting aquatic life, and any other plants, animals, or humans who depend on it. The ion remains in the water and natural removal methods are generally unproductive.
NPR reports that according to Steve Corsi, a hydrologist with the U.S. Geological Survey, the number of times scientists have detected toxic concentrations of chloride in water supplies has doubled over the last two decades. Reasons for the increase are simple, he stated: "We have lots of businesses that have parking lots and sidewalks and such; we have residents who have driveways and sidewalks, and a lot of people use road salt."
Sodium levels are also impacted by road salt runoff, although not as drastically. While chloride is not especially toxic to human health, high levels of sodium in water can be harmful, and are carefully regulated by the U.S. Environmental Agency's drinking water quality standards. By and large the greatest impact of sodium ion increase is on soil chemistry and soil structure.
Researchers at the Western Transportation Institute say that cities are slowly becoming more aware of the damage road salt can do, and making changes wherever they can. Government agencies are testing options such as adding liquid to road salt mixtures to keep it in place for longer periods of time.
Environmental consultants can help government agencies plan and strategize winter maintenance to cause the least harm to the surrounding areas.