Abstract: The use of deicing agents during the winter months is one of many stressors that impact stream ecosystems in urban and urbanizing watersheds. In this study, a long-term dataset collected by citizen scientists with the Missouri Stream Team was used to evaluate the relationships between watershed urbanization metrics and chloride metrics. Further, these data were used to explore effects of elevated chloride concentrations on stream invertebrate communities using quantile regression. While the amount of road surface in a watershed was a dominant factor in predicting the maximum chloride measurement, the median chloride concentration was also strongly related to the amount of medium-to-high density development in the watershed, suggesting that non-municipal salt use is an important contributor to increases in baseflow chloride concentrations. Additionally, chloride concentration appears to be one of the many factors that impact invertebrate density and diversity measurements, with decreases in invertebrate diversity corresponding with the U.S. EPA water quality criteria. Our findings suggest that the use of chloride-based road salt on municipal roads as well as in non-municipal settings is contributing to a loss of diversity and density of aquatic invertebrate communities in urban regions.

Journal article may be found at: https://doi.org/10.1002/ieam.4594