ABSTRACT:Northridge Lakes, in Milwaukee, Wisconsin, receive runoff from a 3.8 square kilometer drainage area. Almost 30 of the watershed is covered by shopping centers, apartment buildings, and roadways. Deicing agents used on the paved areas, primarily NaCl with some CaCl2, dissolved in surface runoff and entered the lakes during the winter season. This highly saline inflow was denser than the receiving lake water and formed a saline‐water stratum at the lakes' bottom. The salinity stratification remained stable until the spring thaw when a rapid decay began. After the stratification had disappeared, the lakes continued to act as a storage site for dissolved salts. Chloride concentrations in the lakes remained well above the levels found in natural lakes until the advent of the next salting season. Furthermore, outflow from the lakes also showed abnormally high salt concentrations year‐ro
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