June 18, 2020

The Clean Water Act and the Coral Reef: A Decision in County of Maui v. Hawai’i Wildlife Fund

Sara A. Colangelo

In the Supreme Court’s first Clean Water Act case in more than a decade, the Court ruled that a federal permit is required if the addition of pollutants through groundwater is the “functional equivalent” of a direct release into navigable waters from a point source, settling a long-standing dispute about the applicability of the Act to indirect discharges.


The County of Maui’s Lahaina wastewater reclamation plant collects sewage, partially treats it, and injects that mixture into four wells hundreds of feet underground. Effluent from the wells travels half a mile, then emerges from submarine fissures in the ocean. Since the 1980s, this plant conveyed excess nutrients and pathogens to a popular coral reef snorkeling spot, Kahekili Beach. The legal dispute concerned whether the pollutants’ journey through groundwater before reaching the ocean exempted the County’s plant from federal permitting requirements under the Clean Water Act (CWA or the Act). 

The CWA requires “point sources” of pollution to secure a National Pollution Discharge Elimination System (NPDES) permit for “any addition of any pollutant to navigable waters.” The Maui case presented a rare situation where everyone agreed the wells qualified as “point sources,” and that the pollution reached “navigable waters.” But for years the parties could not agree whether the County could do indirectly what it could not do directly under the Act –– that is, discharge pollutants into the ocean without a permit. After negotiations failed, local environmental groups sued under the citizen suit provision of the CWA, alleging the County needed an NPDES permit. That permit would mandate more stringent, and costly, treatment standards.

The District Court of Hawaii agreed with the citizen groups, finding that the discharge was “functionally one into navigable water” because the pollutants’ path to the ocean was “clearly ascertainable.” Hydrological evidence played a substantial role in the decision. Geochemists at the University of Hawaii examined seaweed for nitrogen isotopes correlated to anthropogenic sources, fitted drones with infrared lenses to detect plumes of atypically warm water, and conducted a dye tracer study, proving more than 60 percent of the effluent from the wells emerged into the reef. The coral showed obvious degradation during the plant’s operation, and aquatic life and diversity declined.

The Ninth Circuit affirmed, but devised a novel test, holding that permits are required when pollutants are “fairly traceable” from a point source to navigable waters. Under President Obama, the Environmental Protection Agency (EPA) sided with the environmentalists and advanced the Agency’s decades-long position that CWA permitting requirements apply to groundwater discharges with a “direct hydrological connection” to surface waters. This 2018 decision contributed to a circuit split over the indirect discharge question.


The Court ruled 6-3 that an NPDES permit is required if the addition of pollutants through groundwater is the “functional equivalent” of a direct release into navigable waters from a point source. Chief Justice Roberts and Justices Ginsburg, Sotomayor, Kagan, and Kavanaugh joined Justice Breyer’s opinion.

In crafting the “functional equivalent” test, the Court rejected the positions of both Petitioner and Respondent as too extreme. It found the Ninth Circuit’s “fairly traceable” test overbroad, sweeping in examples Congress did not intend such as pollutants carried on a bird’s wing. So too, the more narrowly tailored position of Respondents before the Supreme Court: They argued a permit was necessary whenever pollutants “actually and foreseeably reach navigable surface waters” and suggested the tort concept of proximate cause as a limiting principle. But the Court declined that proposal. Moreover, in a nod to federalism concerns, it observed “the structure of the [CWA] indicates that, as to groundwater pollution and nonpoint source pollution, Congress intended to leave substantial responsibility and autonomy to the States.”

But the Court also found the test offered by the County too narrow. The County proffered a “means of delivery test” under which an NPDES permit is necessary only when a point source is the final conveyance of pollution to navigable waters. If there was intervening media between the point source and navigable waters, no matter how brief in space or time, the discharge was exempt. The Trump Administration filed a brief in support of Maui County. It adopted a new position that discharges to groundwater are excluded from NPDES permitting, per a 2019 EPA “Interpretative Statement.”

The Court dismissed that position as a road map for evasion of the Act, violating its protectionist purpose. “We do not see how Congress could have intended to create such a large and obvious loophole in one of the key regulatory innovations of the [CWA],” Breyer admonished. Under the County’s approach, he theorized a discharger could “simply move the pipe back. . . a few yards, so that the pollution must travel through at least some groundwater before reaching the sea.”

After spurning the parties’ tests, Justice Breyer crafted his own. Focusing on the preposition “from” and its object “to” in the statutory text, he cogitated: Was the discharge to the surface water “from” the point source, the ground water, or both? He also explored everyday usage scenarios, from travelers to meat drippings in a pan. That linguistic analysis, paired with consideration of statutory purpose and structure resulted in the “functional equivalent” test. Justice Breyer explained “[w]hether pollutants that arrive at navigable waters after traveling through groundwater are ‘from’ a point source depends upon how similar to (or different from) the particular discharge is to a direct discharge.”

But the Court acknowledged imprecision in its test. To facilitate implementation by courts and regulators, and provide guidance to the regulated community, Justice Breyer clarified the bounds of “functional equivalence.” “Where a pipe ends a few feet from navigable waters and the pipe emits pollutants that travel those few feet through groundwater. . . the permitting requirement clearly applies.” At the other end of the spectrum, Justice Breyer advised that if the pipe “ends 50 miles from navigable waters” and “emits pollutants that travel with groundwater, mix with much other material, and end up in navigable waters only many years later, the permitting requirements likely do not apply.”

He also provided a non-exhaustive list of factors to consider: (1) transit time; (2) distance traveled; (3) nature of the material through which pollutants travel; (4) extent to which pollutants are diluted or chemically altered through the travel; (5) amount of pollutant entering the navigable waters relative to leaving the point source; (6) manner by or area in which the pollutant enters navigable waters; and (7) degree to which pollution maintains its identify during transit.

Justice Kavanaugh’s concurrence invoked Justice Scalia both in overt reference to his opinion in Rapanos, and in a fervent commitment to textualism regardless of its outcome. Justices Thomas and Gorsuch dissented, arguing the majority’s reading was not supported by the statutory text. Justice Alito dissented separately to emphasize the ruling created a vague standard, “invit[ing] arbitrary and inconsistent application.”

Because the Ninth Circuit applied a broader legal standard, the Court vacated that judgment and remanded the case for analysis under the “functional equivalent” test. Most believe, based on the decisions and factual findings below, the County will be required to get an NPDES permit and that the parties may finally settle. 

Notable Features of the Court’s Rationale

Two elements of the Court’s rationale stand out. First, although the opinion contained a deft grammatical rationale, it was rooted in statutory purpose. Justice Breyer repeatedly invoked the purposes animating the CWA in the same breath as its language and structure. This is a rarity. Modern opinions typically focus on plain meaning informed by dictionary definitions, with statutory structure playing a supporting part, and statutory purpose a passing role at best.

The Maui decision also exemplified the current administration’s view (shared by some on the Court) that Chevron deference is outmoded. The Solicitor General never asked for Chevron deference, and argued simply that the Court should follow EPA’s Interpretive Statement. But none of the Justices deferred to EPA’s new position. Instead, the Court denounced it as “open[ing] a loophole allowing easy evasion of the statutory provision’s basic purposes.” Justice Thomas’ dissent even declared “EPA’s reading is not the best one.”

Although deference was absent, EPA’s long-standing administrative practice still influenced the majority, likely assuaging federalism concerns. The Court remarked that when EPA followed the “direct hydrologic connection” test, there was no “unmanageable expansion of the program.” The Court took comfort that under a legal standard similar to “functional equivalence,” the parade of horribles Petitioner and its amici envisioned for the Court never materialized.

Potential Consequences

We will not know for some time whether Maui will significantly expand the universe of permitees under the Act or how much litigation it might spur. To what extent will “functional equivalence” actually differ from EPA’s prior interpretation based on “hydrologic connection”? For now, we have Justice Breyer’s prescriptions for implementation. He invites EPA to provide specificity through guidance and regulations, and suggests EPA and states could develop general permits for common situations. Further, he notes that “functional equivalence” will become more precise as district courts apply it. Finally, he encourages judges to exercise their discretion when setting penalties under the Act, “mindful” of “when. . .  a party could reasonably have thought that a permit was not required.”

The use and impact of these prescriptions may be delayed. We can surmise there is neither appetite nor, perhaps, time for the Trump Administration to promulgate such technical regulations. Further, we can assume there will be little devotion of resources to government enforcement against indirect dischargers by this EPA. In the meantime, we may see citizen groups pursue claims under “functional equivalence” for certain agricultural, mining, or other industrial dischargers. Additionally, states with delegated NPDES program authority may outline how the factors should be balanced as they issue permits.

Critics lament the majority’s standard as creating insufferable uncertainty and an invitation to litigate. Perhaps so, but probably not. Recall the similar tact Justice Stevens used in Burlington Northern to bound the useful product defense. Further, these cases seem more likely to settle now. A seven factor scientific test is unlikely to be resolved via summary judgment, and a trial on those factors would be quite expensive.

Ultimately, Maui maintains crucial protection for our waters. In delineating the scope of federal permitting based on technical determinations whether pollutants will reach and impact navigable waters, the Court is faithful to the Act while respecting states’ roles. Interestingly, the Court announced its decision the same week as Trump’s EPA finalized a separate regulation limiting federal jurisdiction of the CWA and excluding groundwater in its entirety. Had the Court agreed to Petitioner’s position here, the combined impact with that regulation would have been a severe narrowing of the Act’s protection for surface waters. Instead, the Court signaled the Petitioner and Solicitor General’s constricted reading of the CWA strayed too far from Congress’ intent, handing the environmentalists a defensive victory. While the Maui decision will not invalidate the proposed regulation automatically, it could provide additional grounds for legal challenge to the rule.

    Sara Colangelo


    Sara Colangelo is the Director of the Environmental Law & Policy Program at Georgetown University Law Center. Prior to joining Georgetown, she served as a trial attorney for eight years at the Environment & Natural Resources Division of the U.S. DOJ in the Environmental Enforcement Section. Professor Colangelo is the recipient of the 2020 Fahy Teaching Award for Georgetown Law. She thanks her research assistants Scott Novack ('20) and Karen Vincent ('21) for their help with this article.