County of Maui v. Hawaii Wildlife Fund

The County of Maui operates the Lahaina Wastewater Reclamation Facility, which treats approximately four million gallons of sewage daily and injects the partially treated effluent into four underground injection wells. The effluent travels about half a mile through groundwater before reaching the Pacific Ocean. In 2012, four nonprofit environmental organizations sued the County under the Clean Water Act's citizen suit provision, alleging that the facility was discharging pollutants into navigable waters without a required NPDES permit. The district court ruled for the plaintiffs, finding the discharges functionally equivalent to direct discharges. The Ninth Circuit affirmed using a "fairly traceable" standard. The Supreme Court granted certiorari and issued its decision on April 23, 2020.

In a 6-3 decision authored by Justice Breyer, the Supreme Court vacated the Ninth Circuit's judgment and remanded the case for further consideration. The Court held that a CWA permit is required when there is a direct discharge from a point source into navigable waters or when there is the "functional equivalent" of a direct discharge. The Court rejected both the Ninth Circuit's broad "fairly traceable" standard and the County's proposed bright-line rule excluding all groundwater discharges. It set forth seven non-exhaustive factors to guide the functional equivalence analysis, with transit time and distance traveled identified as the most important considerations.

Whether the Clean Water Act requires a National Pollutant Discharge Elimination System permit when pollutants originate from a point source, travel through groundwater, and then reach navigable waters, and what legal standard should determine such liability.

The decision created significant regulatory uncertainty across multiple industries, including wastewater treatment facilities, agriculture, utilities, energy companies, and developers. The EPA issued draft guidance in December 2020 to assist regulated entities and permitting authorities in applying the functional equivalent test. However, that guidance was later rescinded in September 2021, and the EPA has continued to grapple with implementation challenges. The vague multi-factor balancing test means that regulators, courts, and the regulated community will continue to wrestle with determining whether indirect discharges require CWA permits on a case-by-case basis for years to come. The decision was widely regarded as a significant environmental law ruling that drew support from two conservative justices in the majority.