U.S. Supreme Court Interprets Clean Water Act to Apply to Groundwater Discharges that are “Functional Equivalent” of Direct Discharges to Navigable Waters

April 2020

The U.S. Supreme Court has held, in County of Maui, Hawaii v. Hawaii Wildlife Fund, et al., that point-source discharges to groundwater require a Clean Water Act (CWA) permit if the discharge is “the functional equivalent of a direct discharge.”

The question presented was whether the County of Maui’s sewage treatment plant required a National Pollution Discharge Elimination System permit to inject treated sewage into underground wells from which the sewage filtered through groundwater to the ocean. The plaintiffs argued that because the sewage eventually entered navigable waters, a permit should be required.

The Court’s “functional equivalent” test attempted to steer a middle course between competing views. The Court believed that not requiring a permit for groundwater discharges which plainly affected surface water would create a “loophole” in the permitting scheme and frustrate the intent of the law. On the other hand, the Court concluded that the Ninth Circuit’s “fairly traceable” test was too broad and would lead to permits where Congress had not intended them.

Recognizing that its decision would create some uncertainty, the Court listed seven factors to consider to determine whether a groundwater discharge was functionally equivalent to a direct discharge to navigable waters. Most important is the pollutant’s transit time and distance; other factors include the extent to which pollutants are filtered or diluted before reaching navigable waters. The Court did not try to apply the factors to the case at hand but remanded for further proceedings.

The decision’s outcome is difficult to predict, but certain developments appear likely.

First, the full impact of the decision will not be clear for several years. The Court recognized that its functional equivalence standard would be uncertain in effect until the lower courts and U.S. EPA first had the opportunity to interpret it. This necessarily takes time.

Second, the decision will place renewed focus on the scope of the CWA’s “point source” requirement. Facilities that directly or indirectly discharge pollutants to groundwater, which previously had been considered exempted from the CWA, could come under fresh scrutiny by regulators and citizens’ groups.

Altogether, the decision is likely to be viewed negatively by the regulated community and positively by those seeking to expand the CWA’s reach.

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Sean K. Hungerford is a Partner and Julio N. Colomba is an Associate at Harrison, Temblador, Hungerford & Guernsey LLP in Sacramento, California

© 2020 – Harrison, Temblador, Hungerford & Guernsey LLP. All rights reserved. The information in this article has been prepared by Harrison, Temblador, Hungerford & Guernsey LLP for informational purposes only and does not constitute legal advice.