The Dangers of Chlorides (Salt) in Our Water
“The concentration of chlorides has sharply increased in many bodies of water since the widespread adoption of road salt as a deicer in the 1970s, and the ecological implications of this change have yet to be fully determined. Scientists who study watersheds use elevated chloride levels as one indicator of pollution in a body of water.” Chlorides in Fresh Water
Chlorides are present in both fresh and salt water. They are chemical compounds that typically form from the combination of the gas chlorine with a metal. Chlorides are found in most commonly used salts, including table salt (sodium chloride), and are naturally occurring in small concentrations in freshwater.
Nationwide increases in chlorides in freshwater is a cause for concern, however, and researchers have been trying to identify the reasons for these increases, along with ways we might reverse the trend. Road salt has been identified as one source, and researchers are also looking into agricultural runoff and water softeners.
Alycia Overbo is a graduate student at the University of Minnesota in the Water Resources Science program. She is part of a team studying the impacts of chlorides in ground and surface waters across the state of Minnesota.
So far, the study has found that water softeners are substantial contributors of chlorides in water at wastewater treatment plants in Minnesota, water which then goes back into the environment. Chloride does not go away on its own in the environment, and there is no known cost-effective way to remove it from our waterways.
An overabundance of chloride in water can have a range of health and environmental impacts, some of which are just becoming known. Chloride increases the corrosiveness of water, for example, and has been connected to an increased release of lead in water from corroding metal pipes. High chloride concentrations in water have also been shown to harm aquatic plants and animals.
Everyone who uses salt can help decrease the amount of chloride polluting our waterways. Reducing the amount of deicer you use on your driveway and sidewalk, updating your home water softener to an on-demand model, and installing permeable pavement on your property are several examples. You can find additional tips and information about chloride in freshwater in this factsheet from the University of Rhode Island.
Funding for Understanding Impacts of Salt Usage on Minnesota Lakes, Rivers, and Groundwater was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).