Road salts in urban stormwater: an emerging issue in stormwater management in cold climates

Potential impacts of road salting on the environment have increased by the introduction of certain stormwater management practices. Specific impacts are discussed for four such practices, infiltration facilities, oil and grit separators, stormwater ponds and constructed wetlands. The main concerns about the hazards of chloride-laden stormwater discharges include contamination of groundwater, leaching out of trace metals, densimetric stratification and poor vertical mixing in ponds, direct and indirect toxic effects, benthic drift and reduced biodiversity. The associated environmental risks need to be reduced by chloride source controls, and prevention of excessive chloride accumulations by appropriate design and operation of stormwater facilities in winter months.