Nitrogen and Salt Pollution in Connecticut Streams: A Preliminary Study

Healthy streams are of major importance to provide habitat for aquatic animals, provide safe swimming areas and reduce cost of water treatment when stream water is used for drinking water. However, a 2018 report by the Council of Environmental Quality, Connecticut, found that only 30% of the states' streams are suitable for swimming. Monitoring of surface water can help identify contaminated streams, and evaluate the progress of cleanup efforts. This study focuses on sewage pollution as well as salt pollution, two major concerns in Connecticut streams. A total of 25 different stream locations were sampled over the course of 10 weeks in the summer of 2024 from the south-west region of Connecticut. Water samples were collected at all 25 sites and analyzed using ion chromatography. Macrophyte samples were obtained from 22 streams and analyzed for stable nitrogen isotopic composition. Chloride concentrations ranged between 1.1 to 155 ppm, and as such, none of the streams had values above the threshold level for chronic effects determined by the EPA (230 ppm). However, throughout all of the sites, there was a strong correlation between sodium and chloride ions which indicates that road salt is the main source of these ions in these streams and that salt concentrations could be much higher during winter and spring when road salt is expected to enter the streams. Additionally, 12 streams showed macrophyte δ15N values above 6‰, a threshold often used to indicate contamination by sewage or animal waste, with one stream exhibiting values higher than 10‰. This study indicates that there is a need for larger scale monitoring of Connecticut streams in order to identify and clean up polluted streams.