top of page

The Supreme Court Rules that Some Discharges to Groundwater Require a NPDES Permit

The federal Clean Water Act, 33 U.S.C. §§1251 et seq., requires a permit for discharges from a point source to “navigable waters,” which do not include groundwater. But what about discharges to groundwater that make their way to navigable waters? We reported in our April 2019 newsletter that the U.S. Environmental Protection Agency had issued an “Interpretive Statement” taking the position that no permit under the National Pollutant Discharge Elimination System (NPDES) was required for discharges to groundwater. Last month, in County of Maui, Hawaii, v. Hawaii Wildlife Fund, 140 S. Ct. 1462 (April 23, 2020), the U.S. Supreme Court disagreed.

The County of Maui discharges effluent from its sewage treatment plant into underground wells located approximately one-half mile from the ocean. Environmental groups filed suit for violation of the Clean Water Act, alleging that the County was discharging a pollutant from a point source into navigable waters without a NPDES permit. The allegation was based on a study finding that a significant amount of the effluent was traveling through groundwater and reaching the ocean (a “navigable water”). The district court ruled in favor of the environmental groups and the Ninth Circuit affirmed the lower court’s decision, holding that a permit is required when “the pollutants are fairly traceable from the point source to a navigable water such that the discharge is the functional equivalent of a discharge into the navigable water.” Maui appealed to the Supreme Court. The Solicitor General of the U.S. filed an amicus curiae brief supporting Maui, reiterating the position articulated in EPA’s Interpretive Statement.

The Court rejected the Ninth Circuit’s test, reasoning that using the “fairly traceable” standard could “allow EPA to assert permitting authority over the release of pollutants that reach navigable waters many years after their release...and in highly diluted forms.” However, the Court also rejected EPA’s position, pointing out that it would create a loophole in which a discharger could avoid NPDES permitting requirements by discharging to the ground a few feet away from a navigable water.

The Court held that a NPDES permit is required for any point source discharge to groundwater “if that discharge is the functional equivalent of a direct discharge from the point source into navigable waters.” The Court did not define “functional equivalent,” however, stating that the determination would be fact-specific. Nevertheless, the decision listed a number of potentially relevant factors, including the distance of the discharge from navigable waters and the time required for pollutants to travel thereto. The Court did not state whether Maui’s discharge was the “functional equivalent of a direct discharge,” instead remanding the case for the lower court to make that determination. EPA and the lower courts will now take on the task of parsing the new test’s meaning and practical implications.


bottom of page