Crow Wing County and the Crow Wing Soil and Water Conservation District began chloride water sampling in 2019. The goal was to monitor the long-term effects of applying road salt.
Monitoring encompassed seven out of these 10 county lakes along county roads: Big Trout, Cross, Edward, Gilbert, Nokay, Pelican, Rabbit, Rock, Ross and Upper South Long Lake. The initial data indicated safe chloride levels ranging from 2.88 to 15.5 milligrams per liter.
Chloride is a permanent pollutant. One teaspoon of salt pollutes 5 gallons of water. A lake is impaired by chloride if two or more samples exceed 230 milligrams per liter within a three-year period, or one sample exceeds 860 milligrams per liter.
The county highway department is certified through the Minnesota Pollution Control Agency on how to protect water resources by using less salt while maintaining safe paved surfaces. Around 403,600 tons of road salt are applied to Minnesota roads each year, according to officials.
Chloride negatively affects fish and aquatic bugs by lowering diversity and productivity. Native fish and bug species are more sensitive to chloride changes.
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The county chloride monitoring data shows all seven of the lake’s chloride results are below the chloride standards set by the Minnesota Pollution Control Agency.
