On April 23, 2020, the United States Supreme Court issued its decision in County of Maui v.  Hawaii Wildlife Fund, No. 18-260, addressing whether the Clean Water Act (CWA) requires a permit when pollutants originate from a point source, but are conveyed to navigable waters by a nonpoint source, such as groundwater.  The Court found the CWA may require a permit when there is a direct discharge, or a functional equivalent of a direct discharge, of pollutants from a point source into navigable waters.

County of Maui involved effluent discharges from injection wells at wastewater reclamation facility run by the County of Maui in Hawaii.  Maui County pumps partially treated sewage underground, where it travels about half a mile through groundwater to the ocean.  Environmental groups sued, claiming the CWA required Maui County to obtain a permit for its discharges into navigable waters.  The U.S. Court of Appeals for the Ninth Circuit ruled a permit is required for non-direct discharges that are fairly traceable from the point source to a navigable water.

The Supreme Court vacated that decision by a 6-3 vote and also rejected the EPA’s interpretation that groundwater is never subject to regulation, as inconsistent with the purpose of the CWA.   Instead, the Court found that the CWA requires a permit if there is a functional equivalent of a direct discharge from a point source into navigable waters. 

The Court described a non-exhaustive list of seven factors to consider when deciding whether a discharge is the functional equivalent of a direct discharge, the most important of which are the time and distance. Based on the facts in County of Maui, the discharge of pollutants through groundwater to navigable waters is subject to the permitting requirement of the CWA because it is the functional equivalent of a direct discharge.

Operations that result in point source discharges to groundwater may need to evaluate their systems to determine the potential application of the CWA.  This determination will require a fact intensive analysis which could be open to numerous interpretations.  As County of Maui provides no bright-line test, it will be left to the Courts to manage application of the functional equivalent standard’s relevant factors.