Oral Presentation Society for Freshwater Science 2026 Annual Meeting

Salinization of lakes in west Michigan: how problematic is it?  (133811)

Alan Steinman 1 , Sean Woznicki 1 , Michael Hassett 1 , Katie Tyrrell 1
  1. Annis Water Resources Institute-GVSU, MI, United States

Salinization of freshwater ecosystems is a growing concern, especially in north temperate regions due to runoff from de-icing salts.  Studies have identified a positive association between lakes with elevated chloride (Cl-) concentrations and proximity to major highways but it is less clear if elevated Cl- is found in more rural regions. This knowledge gap inspired a lake survey in 5 west Michigan counties to determine the extent of chloride contamination. Our results indicated an absence of elevated Cl- with the exception of previously studied urbanized lakes. Land use affected both Cl- and conductivity, with forest land cover negatively correlated and developed land positively correlated to both parameters. In addition, there was a moderately negative correlation between Cl- and distance to major roads and a moderately positive correlation between chloride and estimated salt application. The epilimnion and hypolimnion chloride measurements were compared with chloride predictions from previously published models; Cl- levels fell within model prediction intervals, although Cl- levels compared to a second model suggested our sampled lakes had not reached a Cl- equilibrium. We developed a Michigan-specific epilimnion and hypolimnion chloride model using our samples and data from the U.S. Water Quality Portal, which predicted greater Cl- concentrations in lakes with urbanized watersheds.  Although the lakes surveyed in this study currently are not being impacted by road salt runoff, the correlation data suggest they may be at risk in the future; increasing air temperatures may offset this risk if less road salt is needed to protect the roads.