Road salt impacts on ground-water quality - the worst is still to come

The Metropolitan Toronto area of southern Ontario, Canada, receives well over 100 000 t (tonnes) (Mg) of NaCl annually. Only 45% of the salt applied is being removed annually from the catchment in surface-water flow, the remainder entering temporary storage in shallow subsurface waters. The data from this study indicate that if present rates of salt application are maintained, chloride concentrations in ground waters discharging as stream base …