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U.S. Supreme Court Issues a Major Ruling on NPDES Permits

National Pollution Discharge Elimination System NPDES Permits Under Clean Water Act

On April 23, 2020, the United States Supreme Court issued a significant decision regarding when National Pollution Discharge Elimination System (NPDES) permits are needed for “point source” discharges under the Clean Water Act. The Clean Water Act forbids “any addition” of any pollutant from “any point source” to “navigable waters” without an appropriate permit from the United States Environmental Protection Agency (EPA).

Wastewater Reclamation Facility Pollutant to Navigable Waters

The Supreme Court’s decision stemmed from a citizens’ lawsuit filed by several environmental groups against the County of Maui, Hawaii. Maui operates a wastewater reclamation facility that collects sewage from the surrounding area, partially treats it, and pumps the treated water through four wells hundreds of feet underground. This effluent, which amounts to about four million gallons a day, then travels approximately one-half mile through groundwater to the Pacific Ocean. The environmental groups claimed that Maui has been discharging a pollutant to “navigable waters,” namely, the Pacific Ocean, without an NPDES permit required by the Clean Water Act.

The District Court found that a considerable amount of effluent from the wells ended up in the Pacific Ocean (navigable water). The District Court wrote that, because the “path to the ocean is clearly ascertainable,” the discharge from Maui’s wells into the nearby groundwater was “functionally one into navigable water” and granted summary judgment in favor of the environmental groups. The Ninth Circuit affirmed the District Court, but it described the relevant statutory standard differently. Specifically, the Ninth Circuit wrote 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.” The court left “for another day the task of determining when, if ever, the connection between a point source and a navigable water is too tenuous to support liability.”

The Clean Water Act Groundwater Point Source

Maui contended, together with the Solicitor General of the United States, that the Clean Water Act’s permitting requirement does not apply if a pollutant, having emerged from a “point source,” must travel through any amount of groundwater before reaching navigable waters. Maui argued that the meaning of “from any point source” is not about where the pollution originated, but about how it got there. Thus, Maui claimed a permit is required only if a point source ultimately delivers the pollutant to navigable waters. By contrast, if a pollutant travels through groundwater, then the groundwater is the conveyance and no permit is required.

The Supreme Court rejected these arguments based on its review of the Clean Water Act. The Court ruled that the statutory provisions of the Act at issue require 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 based its ruling on several factors:

  1. The context of the Clean Water Act limits the reach of the phrase “from any point source” to a range of circumstances narrower than that which the Ninth Circuit’s “fairly traceable” interpretation suggests. At the same time, the context is significantly broader than the total exclusion of all discharges through groundwater.
  2. The Ninth Circuit’s “fairly traceable” limitation could allow the EPA to assert permitting authority over the release of pollutants that reach navigable waters many years after their release. The Supreme Court concluded that Congress did not intend to provide the EPA with such broad authority. The Court stated that to interpret “from” so broadly might require a permit in unexpected circumstances, such as, e.g., the 100-year migration of pollutants through 250 miles of groundwater to a river.
  3. The Clean Water Act’s structure indicates that, as to groundwater pollution and nonpoint source pollution, Congress left substantial responsibility and autonomy to the States and did not give the EPA authority that could seriously interfere with this state responsibility.
  4. The Clean Water Act’s legislative history strongly supports the conclusion that the permitting provision does not extend so far.
  5. Longstanding regulatory practice shows that the EPA has successfully applied the permitting provision to pollution discharges from point sources that reached navigable waters through groundwater using a narrower interpretation than that of the Ninth Circuit.


The Supreme Court acknowledged that there are some difficulties with its “functional equivalent” approach. In particular, the Court stated that this approach does not, on its own, clearly explain how to deal with middle instances and that there are too many potentially relevant factors applicable to factually different cases for the Court now to use more specific language. The Court cited some of the factors that may prove relevant depending upon the circumstances of a particular case:

  1. Transit time
  2. Distance traveled
  3. The nature of the material through which the pollutant travels
  4. The extent to which the pollutant is diluted or chemically changed as it travels
  5. The amount of pollutant entering the navigable waters relative to the amount of the pollutant that leaves the point source
  6. The manner by or area in which the pollutant enters the navigable waters
  7. The degree to which the pollution (at that point) has maintained its specific identity

The Court, however, indicated that difficulties can be overcome by the guidance provided by courts through decisions in individual cases and by the guidance provided by the underlying objectives of the Clean Water Act. Specifically, the Court indicated that lower court decisions should not create serious risks either of undermining state regulation of groundwater or of creating loopholes that undermine the statute’s basic federal regulatory objectives. The Court further indicated that the EPA can provide administrative guidance in numerous ways, including through, for example, grants of individual permits, the promulgation of general permits, or the development of general rules. And that over the years, the EPA and the states have often considered the Clean Water Act’s application to discharges through groundwater.

This decision by the Supreme Court adds another dimension that point source dischargers must take into consideration when evaluating whether any NPDES permits must be procured. The environmental law attorneys at Norris McLaughlin stand ready to assist those that have permitting issues to evaluate and address these issues. If you have any questions about this post or any related matters, please feel free to contact me at or 484-765-2211.