Review of water quality impacts of winter operation of urban drainage

Urban snowpacks accumulate large quantities of solids and contaminants, whi ch originate from such sources as airborne fallout, vehicular deposition, a nd applied grit and salt. Both contaminants and solids may be quickly relea sed during the periods of snowmelt and, consequently, melting contaminated snow in urban areas in cold climates has the potential to substantially imp act the water quality of receiving water bodies. Although data on the water quality impacts of meltwater are relatively scarce, instances of toxicity of: the highly concentrated first flush and deterioration of the receiving water quality by winter discharges of solids and chemicals have been docume nted. Common rainfall-runoff management techniques do not usually address s nowmelt impacts because of the cold weather effects on biological systems a nd physical processes. Further research on adaptation of conventional storm water management techniques to cold climate conditions is needed.