Snowmelt from streets and highways in snowbelt areas of North America is polluted by traffic emissions, atmospheric deposition, and deicing chemicals. The among the most severe are those water quality impacts caused from snowmelt discharges contaminated from the use of deicing chemicals. Examples of which include pollution by cyanides originating from the salt, increased toxicity from metals, direct effects of elevated salt concentrations, and the acidic leaching of chemicals from snow and soils. To reduce the adverse ecological impacts on receiving water bodies, watershed water quality management during the winter months requires consideration of the type of drainage and the selection and use of deicing compounds. Drainage type is however, the primary factor in the selection of a management strategy. Discussed and compared are the pollution impacts and management of snowmelt from the three most common urban drainage systems: (1) drainage by storm sewers; (2) drainage by combined sewers; and (3) drainage by roadside swales. Pollution impact on receiving waters is most severe from basins served by storm sewers. Sampling of snowmelt pollution and their discharges resulting from storm sewers was conducted in Milwaukee, Wisconsin and Edmonton, Alberta. Compared are the differences in winter urban diffuse pollution from a community that relies entirely on salt versus pollution from a community that uses an abrasive-salt mixture, both of which make use of a storm sewer drainage system. Discussed specifically is how salinity (chlorides), cyanides and increased toxicity of metals should be addressed in the selection and design of Best Management Practices around watersheds where salt and abrasives are used for deicing.
