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Supreme Court Seeks Middle Ground as to the Scope of the Clean Water Act

April 24, 2020

The US Supreme Court struck a compromise this week as to whether the federal Clean Water Act (CWA) can be used to regulate discharges to groundwater that may reach “navigable waters.” The Supreme Court found that certain discharges to groundwater can be regulated under the CWA, for example, by requiring permits for such discharges or taking enforcement action as to the same, but failed to establish a bright line rule.

The decision involves the long-running matter of County of Maui v. Hawai'i Wildlife Fund. The County of Maui (Maui) operates a wastewater reclamation facility on the island of Maui, Hawaii. The facility collects sewage from the surrounding area, partially treats it, and pumps the treated water hundreds of feet underground through four injection wells. Some of this effluent then travels one-half mile, through groundwater, to the ocean. The CWA requires permits for discharges from “point sources” to navigable waters. However, where a point source discharges to groundwater (and not directly to navigable water), applicability of the CWA is less certain.

Environmental groups sued, claiming that Maui was discharging pollutants from a point sources to navigable waters (the Pacific Ocean) without a CWA permit. Maui argued that because the discharge from the point source was to groundwater and not navigable waters, no permit was required. Ultimately, the Ninth Circuit held that discharges to groundwater required a CWA permit if the pollutants in the discharge are “fairly traceable from the point source to a navigable water.”

The Supreme Court narrowed the Ninth Circuit’s ruling, requiring 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 from the point source into navigable waters.” (Emphasis added.) However, rather than establishing a clear standard of what constitutes a “functional equivalent,” the majority opinion instead lists potentially relevant considerations, including:

  • how long it takes the pollutant to reach navigable waters;
  • the distance the pollutant travels before reaching navigable waters;
  • 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 entering the navigable waters relative to the amount of the pollutant that leaves the point source;
  • the manner by or area in which the pollutant enters the navigable waters; and
  • the degree to which the pollution (at that point) has maintained its specific identity.

The Court acknowledged that, “Time and distance will be the most important factors in most cases, but not necessarily every case.”

The Supreme Court recognized that virtually all water, polluted or not, eventually makes its way to navigable water and that the Ninth Circuit’s “fairly traceable” standard would have allowed the US Environmental Protection Agency (EPA) to broadly assert permitting authority, including over the release of pollutants that reach navigable waters many years after their release and in highly diluted forms.

In a concurring opinion, Justice Kavanaugh emphasized the plurality opinion in Rapanos v. United States, wherein Justice Scalia argued that polluters could not “evade the permitting requirement . . . simply by discharging their pollutants into noncovered intermittent watercourses that lie upstream of covered waters.”

As to the dissents, Justice Thomas (joined by Justice Gorsuch) argued that the CWA excludes anything other than a direct discharge to navigable waters. Writing separately, Justice Alito assailed the majority’s “functional equivalent” test as an implausible interpretation of the statutory text with no clear meaning as to its application.

The Supreme Court remanded the case to the Ninth Circuit for further consideration.

The Supreme Court’s decision comes two days after the April 21, 2020, issuance by the EPA and the US Army Corps of Engineers of their Navigable Waters Protection Rule, which significantly alters the universe of water deemed to be navigable waters. The rule becomes effective on June 22, 2020, and is expected to be the subject of numerous court challenges, thereby adding more uncertainty to the scope of the jurisdictional reach of the federal CWA.


This memorandum is a summary for general information and discussion only and may be considered an advertisement for certain purposes. It is not a full analysis of the matters presented, may not be relied upon as legal advice, and does not purport to represent the views of our clients or the Firm. Eric Rothenberg, an O’Melveny partner licensed to practice law in Missouri and New York, Kelly McTigue, an O’Melveny partner licensed to practice law in California, and Bob Nicksin, as O’Melveny counsel licensed to practice law in California, contributed to the content of this newsletter. The views expressed in this newsletter are the views of the authors except as otherwise noted.

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