In two cases decided the same day, Kentucky Waterways Alliance v. Kentucky Utility Co., 905 F.3d 925 (6th Cir. 2018), and Tennessee Clean Water Network v. Tennessee Valley Authority, 905 F.3d 436 (6th Cir. 2018), the Sixth Circuit held that pollutants discharged into groundwater that is hydrologically connected to navigable waters are not regulated by the Clean Water Act, which prohibits discharges of pollutants from a point source into navigable waters without a National Pollutant Discharge Elimination System (NPDES) permit.

In Kentucky Waterways Alliance and Tennessee Clean Water Network, plaintiffs urged the Sixth Circuit to adopt the “hydrological connection” theory which would allow the Clean Water Act to regulate discharges from a point source and into groundwater hydrologically connected to navigable waters. Under that theory, plaintiffs alleged that groundwater flow collected pollutants from defendants’ ash ponds and discharged them into nearby navigable waters in violation of the Clean Water Act. Kentucky Waterways Alliance, 905 F.3d at 931; Tennessee Clean Water Network, 905 F.3d at 441. The Sixth Circuit rejected the “hydrological connection” theory and held that point sources must discharge pollutants directly into navigable waters to be regulated by the Clean Water Act. Kentucky Waterways Alliance, 905 F.3d at 933-34; Tennessee Clean Water Network, 905 F.3d at 444.

The court based its decision, in part, on a textual interpretation of the Clean Water Act which limits the amount of pollutants “discharge[d] into navigable waters.” Kentucky Water Ways Alliance, 905 F.3d at 934. The court determined that the word “into” requires directness. Therefore, pollutants must be discharged from point sources directly into navigable waters. Id.

These decisions provide an added a layer of protection to owners of surface impoundments because even if the court adopted the “hydrological connection” theory, plaintiffs must still prove that pollutants are discharged from a point source. Id. The court dismissed the theory that groundwater is a point source and, although dicta, expressed serious doubts about plaintiffs’ ability to prove ash ponds are point sources. Id. at 934 n.8. As a result, in the Sixth Circuit, owners of surface impoundments that sit atop hydrologically connected groundwater will not be subject to NPDES permitting unless the U.S. Supreme Court says otherwise.