Salting Our Freshwater Lakes: RBC Researcher Kait Farrell in PNAS, Washington Post
44% of a sample of 371 US Lakes show signs of long-term salinization, according to a new paper in the Proceedings of the National Academy of Science by Kait Farrell and 14 others. Although no agency systematically tracks the application of salt to de-ice roads, researchers across the country knew that salt was making its way into freshwater ecosystems as snowmelt and spring rains wash it into ditches, creeks, and streams. So, the study’s authors assembled a large database of lake studies that tracked chloride levels tracks for at least ten years. Among other findings, they estimate that if the trends continue, 14 of the 371 lakes would exceed the EPA’s “aquatic life criterion concentration” of 230 milligrams per liter, which borders on the EPA’s recommendation that drinking water sources not exceed 250 milligrams per liter. As the figure below shows, chloride levels were strongly related to the amount of impervious surface in a watershed, one measure of the density of roads and pavement.This study was also featured in the Washington Post on April 10; read the full article here.