Meltdown: Road Salt in Wingra Watershed

THE USE OF SALT AFFECTS OUR LAKES

The city of Madison began using sodium chloride, rock salt, as a street deicer in 1959-1960.  The Madison Department of Public Health began a study to determine if this deicing agent would affect the water quality or the ecology of the Madison Lakes.  In the data collected from 1956-1974, the Public Health Department found a slight increase in the chloride content of the area lakes, but “the concentrations remained well below acceptable water supply standards for drinking or swimming.  And the deicing chemicals were not detrimental to aquatic life”, according to the Madison Department of Public Health. Thus the salt reduction policy came into affect.

Our project was conducted by Edgewood College students researching how Lake Wingra is effected by road salt.  In the study, we visited different locations of Lake Wingra during the month of March.  We took samples of the water at outfall points on days when the weather was warm and snow was melting.   

Salt in Lake Wingra

Salt Reduction Policy

Graph-Streets Maintained and Salt Use

Graphs-Sodium and Chloride

Graph-Salt Application per Mile of City Street

Alternative Testing

Graphs-Salt Use

Our Study-Testing Chloride Levels

Resources