In two opinions issued on September 24, 2018, the Sixth Circuit ruled that discharges of a pollutant to surface waters through groundwater do not require a National Pollutant Discharge Elimination System permit, pursuant to the Clean Water Act. Significantly, the Sixth Circuit decision directly contradicts decisions issued earlier this year by the Fourth and Ninth Circuits on this same issue.

In both Kentucky Waterways Alliance v. Kentucky Utilities Co., No. 18-5115, and Tennessee Clean Water Network v. Tennessee Valley Authority, No. 17-6155, the Sixth Circuit considered claims brought by environmental groups via citizen suits alleging that power plants violated the Clean Water Act by failing to obtain NPDES permits for the discharge of pollutants from coal ash ponds to groundwater that subsequently migrated into surface waters. The Sixth Circuit found that in order to fall within the Clean Water Act’s reach, pollution must enter navigable waters via a point source discharge to constitute the “discharge of a pollutant” under the Clean Water Act and that a discharge to groundwater — even if the groundwater is hydrologically connected to a navigable water — is not a point source discharge. The Sixth Circuit emphasized that the Clean Water Act intended for such non-point source discharges of pollution to be regulated by the states.

Earlier this year, the Ninth and Fourth Circuits conversely held in Hawaii Wildlife Fund v. County of Maui and Kinder Morgan Energy Partners LP v. Upstate Forever, respectively, that Clean Water Act jurisdiction does extend to pollution caused by unpermitted discharges that reach surface water through groundwater. 

The Sixth Circuit decision is significant, as the clear contradiction between the Ninth and Fourth Circuit opinions and the Sixth Circuit opinions makes the issue ripe for U.S. Supreme Court review. Liability under the Clean Water Act for the discharge of pollutants to groundwater could have a substantial impact on a wide array of industries.

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