The Tennessee Valley Authority isn’t responsible for contaminating the nearby Cumberland River with coal ash deposits via groundwater, a federal appeals court ruled Sept. 24.

A panel for the U.S. Court of Appeals for the Sixth Circuit, in a 2-1 decision, overturned a lower court ruling that found the TVA liable for allegedly releasing heavy metals and other pollutants from coal ash ponds belonging to the Gallatin Fossil Plant in Sumner County, Tenn.

At issue was whether the Clean Water Act regulates contamination of federally protected waters via groundwater leaching of pollutants from coal ash ponds. The...