The slow and steady salinization of Sparkling Lake, Wisconsin

The concentrations of conservative solutes in seepage lakes are determined by the relative inputs of precipitation vs. groundwater. In areas of road salt application, seepage lakes may be at high risk of salinization depending on groundwater flow. Here, we revisit a 1992 analysis on the salinization of Sparkling Lake, a deep seepage lake in Northern Wisconsin. The original analysis predicted a rapid increase in chloride concentrations before reaching a steady steady of 8 mg L-1 by 2020. Forty years of monitoring Sparkling Lake show that rather than reaching a dynamic equilibrium, chloride concentrations have steadily increased. We update the original box model approach by adding a soil reservoir component that shows the slow steady rise in chloride is the result of terrestrial retention. For freshwater rivers and lakes, chloride retention on the landscape will both delay chloride impairment and prolong recovery and must be considered when modeling future chloride contamination risk.

Automated summary

The concentrations of solutes in seepage lakes are influenced by precipitation and groundwater inputs. Seepage lakes in areas where road salt is applied may face a high risk of salinization. Monitoring of Sparkling Lake over 40 years shows that chloride concentrations have steadily increased, indicating terrestrial retention as a factor. When modeling future chloride contamination risk, the retention of chloride on the landscape should be considered.