A recently released study conducted by the USGS Wisconsin Water Science Center has shown that streams are being adversely affected by the use of salt for deicing roads, sidewalks and parking lots. The study focused especially on eastern Wisconsin and Milwaukee, but also included other northern U.S. cities.
In eastern and south-central Wisconsin, chloride levels exceeding US EPA chronic water quality criteria were found in 100 percent of urban streams during winter. These chloride levels are the determinant of toxicity in the water. Further, the chloride levels of the water were not declining enough even by the time summer came in order for those streams to be suitable for many aquatic inhabitants. Nationally, 55 percent of northern streams samples chloride levels exceeded US EPA chronic water-quality criteria.
Matthew C. Larsen, the Associate Director for Water at the USGS says: "This study suggests the need for advancements that will reduce salt loads to surface waters." Read the full release: "Many Urban Streams Harmful to Aquatic Life Following Winter Pavement Deicing" on the USGS website. For further reading suggestions, see our recommended reading list on Understanding and Protecting Groundwater.
Photo by Michael Pereckas