RICHMOND, Va. (AP) — A federal appeals court has found that Dominion Energy’s discharge of arsenic from a coal ash storage site through groundwater into surrounding waters doesn’t violate the U.S. Clean Water Act.

A three-judge panel of the 4th U.S. Circuit Court of Appeals on Wednesday reversed a ruling by a federal judge who found that Virginia’s largest electric utility had violated the federal law.

U.S. District Judge John Gibney Jr. ruled in 2017 in a lawsuit filed by the Sierra Club that arsenic is illegally flowing from a landfill and ponds where Dominion Energy stores coal ash in Chesapeake.

The appeals court, however, agreed with Dominion that the lower court was wrong when it found that the pollution from the stored coal ash came from a single identifiable source covered by the act.