## Facts

- The Clean Water Act (CWA) generally bars the discharge of pollutants from a point source into navigable waters without a permit issued under the National Pollutant Discharge Elimination System (NPDES).
- When Congress enacted the CWA, it declined the Environmental Protection Agency’s request for authority to regulate groundwater as such, instead relying in part on state-based groundwater protections.
- The County of Maui operated the Lahaina Wastewater Reclamation Facility, which collected and treated sewage and then injected treated effluent into underground injection wells.
- The effluent entered groundwater and traveled toward the ocean; a tracer dye study showed that pollutants from the injection wells could be detected in the Pacific Ocean roughly a half mile away.
- In 2012, Hawai‘i Wildlife Fund and other environmental organizations filed a CWA citizen suit, alleging Maui was discharging pollutants to the Pacific Ocean without an NPDES permit.
- The federal district court granted summary judgment to the environmental organizations, reasoning that the discharge to the ocean through groundwater was effectively the same as a direct discharge to navigable waters because the pathway was ascertainable.
- The Ninth Circuit affirmed using a “fairly traceable” approach, holding that a permit is required when pollutants are fairly traceable from a point source to navigable waters.
- The Supreme Court granted certiorari to address whether, and when, the CWA requires a permit when pollutants originate from a point source but reach navigable waters through groundwater.

## Issues

1. Does the CWA require an NPDES permit when pollutants originate from a point source but are conveyed to navigable waters by groundwater (a nonpoint source medium)?
2. If the CWA can apply to such releases, what standard determines when the connection between the point source and navigable waters is close enough to require a permit?

## Decision

- Yes in some circumstances: the CWA requires a permit 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 the County’s and EPA’s categorical position that the CWA never applies when pollutants travel through groundwater before reaching navigable waters.
- The Court rejected the Ninth Circuit’s “fairly traceable” test as too broad because it could sweep in remote and highly attenuated connections.
- The Court vacated the Ninth Circuit’s judgment and remanded for application of the “functional equivalent” standard to Maui’s injection-well discharges (6–3).

## Legal Principles

- The CWA’s NPDES program applies to the “addition of any pollutant to navigable waters from any point source,” and the statutory word “from” can cover more than only immediately adjacent, pipe-to-water discharges.
- A rule limited to only literally direct discharges would create an obvious gap: a polluter could place a pipe just short of a waterbody and rely on an intervening medium to carry pollutants the remaining distance.
- A discharge through groundwater may require an NPDES permit when it is the functional equivalent of a direct discharge from the point source into navigable waters.
- The functional-equivalent inquiry is case-specific; transit time and distance traveled will usually matter most.
- Nonexclusive factors the Court identified include:
  - How long the pollutant takes to reach navigable waters.
  - How far the pollutant travels.
  - The nature of the material through which the pollutant travels.
  - The extent to which the pollutant is diluted or chemically changed as it travels.
  - The amount of pollutant that enters navigable waters relative to the amount leaving the point source.
  - The manner or area in which the pollutant enters navigable waters (for example, one outlet versus diffuse seepage).
  - The degree to which the pollutant maintains its specific identity.
- The decision does not treat groundwater itself as a “navigable water” or as a “point source”; groundwater can serve as the transport route in evaluating whether a release is functionally equivalent to a direct discharge.
- Courts may develop the standard through decisions in individual cases, and EPA permitting practice and guidance may also inform how the test is applied.

## Conclusion

County of Maui holds that the CWA’s NPDES permitting requirement reaches not only direct point-source discharges into navigable waters but also some releases that travel through groundwater, when the release is the functional equivalent of a direct discharge, evaluated under a fact-based set of considerations led most often by time and distance; the Court vacated and remanded for application of that standard.


County of Maui v. Hawaii Wildlife Fund, 140 S. Ct. 1462 (2020)