Landmark U.S. Supreme Court Case Holds that the Clean Water Act Can Encompass Groundwater

The United States Supreme Court in County of Maui v. Hawaii Wildlife Fund, 590 U.S. ___ (2020) issued a landmark decision involving the Clean Water Act (CWA), holding that a permit is required when there is a direct discharge of a pollutant from a point source or when there is a “functional equivalent” into navigable waters. The County of Maui owns and operates four wells at the Lahaina Facility, the principal municipal wastewater treatment plant for West Maui. This plant receives approximately 4 million gallons of sewage every day. The Lahaina Facility treats the sewage and pumps the treated water into the ground through its wells. Some of the effluent travels through groundwater and reaches the Pacific Ocean. In County of Maui, the Supreme Court grabbled with the issue of whether the 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 purpose of the CWA is to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters. Section 301 of the Act (33 U.S.C. § 1311) prohibits the discharge of any pollutant into navigable waters by any person from a point source, unless the discharger obtains a National Pollutant Discharge Elimination System (NPDES) permit from the Environmental Protection Agency (EPA).

Maui challenged the necessity of the NPDES permit, arguing that a permit is only required if a point source ultimately delivers the pollutant to navigable waters. Thus, if a pollutant travels through groundwater, then the groundwater, a non-point source, is the conveyance and no permit should be required. The Solicitor General, in support of Maui’s position, argued that the proper interpretation of the statute should exclude the release of pollutants to groundwater, even when such release could result in the conveyance to navigable waters via groundwater. Conversely, environmental groups argued for a broad interpretation of the statute, which covered all pollutants that are “fairly traceable” to a point source.

The Supreme Court rejected both interpretations, opting for a middle ground approach. It created a multi-factor test to determine whether a pollution discharge is the “functional equivalent” of a direct discharge to surface waters. The Court provided that the functional equivalent test must be applied on a case-by-case basis, evaluating a non-exhaustive list of seven factors, including:

In reaching its compromise position, the Court reasoned that the narrow interpretation urged by the Solicitor General would seriously interfere with the EPA’s ability to regulate point source discharges and that Congress would not have intended to create such a large and obvious loophole. Similarly, in declining to apply Chevron deference to the Agency’s interpretation, the Court reasoned that EPA’s interpretation was unreasonable because it would create an easy loophole to circumvent the CWA’s basic purposes. Interestingly, the Court acknowledged the limitations of its “functional equivalent” test, stating that it “does not, on its own, clearly explain how to deal with middle instances. But there are too many potentially relevant factors applicable to factually different cases for this Court now to use more specific language.” However, the Court expressed optimism that additional guidance will be provided in the future through court decisions and administrative guidance from the EPA.