County of Maui v. Hawaii Wildlife Fund
The Supreme Court ruled that the Clean Water Act can require a permit even when pollutants travel through groundwater before reaching the ocean — but only when that indirect path is the 'functional equivalent' of dumping directly into navigable waters.
The ruling charts a middle course between two extreme positions: it rejects both the broad view that permits are needed whenever pollution can be traced to its source, and the narrow view that any groundwater in the path exempts a discharger entirely, leaving lower courts and the EPA to apply a multifactor test case by case.
“We hold that the statute 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's central holding on when the Clean Water Act's permit requirement applies to indirect discharges through groundwater.
How it got here: Environmental groups filed a citizens' suit in federal district court; the district court granted summary judgment against Maui; the Ninth Circuit affirmed using a "fairly traceable" standard; the Supreme Court granted certiorari to resolve a split among the federal appeals courts.
The Case in Depth
What happened
Maui County, Hawaii, operates a wastewater treatment facility that pumps about four million gallons of partially treated sewage per day into four underground wells. That effluent travels roughly half a mile through groundwater before reaching the Pacific Ocean. A group of environmental organizations sued Maui, arguing the facility was discharging pollutants into navigable waters without the federal Clean Water Act permit the law requires.
The question before the Court
Does a county need a federal Clean Water Act permit when its wastewater facility pumps treated sewage underground, and that effluent travels through groundwater to reach the ocean?
The Court's answer
Neither extreme position is correct. The Court held that the Clean Water Act's permit requirement does apply to discharges that travel through groundwater before reaching navigable waters — but only when the indirect discharge is the "functional equivalent" of a direct discharge from the point source into those waters. Congress did not intend to give the EPA the sweeping authority that would follow from requiring permits whenever pollution can be "fairly traced" to its origin, nor did it intend to let dischargers avoid regulation simply by ensuring any groundwater lies between their pipe and the sea.
The most important factors in deciding whether a discharge qualifies as a "functional equivalent" are time and distance. A facility whose effluent travels a few feet through groundwater to reach the ocean clearly needs a permit; one whose pollution takes a hundred years to migrate 250 miles likely does not. Other factors — including how much the pollutant is diluted, how it changes chemically, and how much ultimately reaches navigable waters — may also be relevant. Because the Ninth Circuit applied a different, broader standard, the case is sent back for reconsideration under this new framework.
Curious how the Court got there? See the step-by-step legal reasoning →
Why it matters
Wastewater facilities, industrial operations, and others that pump pollutants underground near coastlines or rivers may need federal permits they previously thought they could avoid. At the same time, the ruling does not automatically sweep in the roughly 650,000 injection wells or 20 million septic systems nationwide; whether any particular discharge requires a permit will depend mainly on how far the pollution travels and how long the journey takes.
What changes now
The case returns to the Ninth Circuit, which must evaluate Maui's discharges under the new "functional equivalent of a direct discharge" standard. Given the facility's effluent travels only about half a mile through groundwater before reaching the Pacific Ocean, a permit may well be required on remand. More broadly, EPA and lower courts will need to develop more specific guidance — through permitting decisions, general rules, and individual rulings — on exactly where the line falls under the multifactor test.
What this does not decide
The Court does not provide a bright-line rule for when indirect groundwater discharges require a permit; it expressly acknowledges its test does not clearly resolve "middle instances." The ruling also does not decide whether the millions of ordinary homeowners with septic systems, or operators of the roughly 650,000 injection wells nationwide, must obtain permits — those questions will depend on the facts of each situation.
Concurrences and dissents
Concurrence — Justice Kavanaugh
Justice Kavanaugh joined the majority in full but wrote separately to make three points: the ruling is consistent with Justice Scalia's plurality opinion in Rapanos v. United States; the vagueness in the standard reflects the vagueness in Congress's statutory language, not the Court's drafting; and contrary to the Thomas dissent's critique, the majority does identify time and distance as the most important factors, which will provide meaningful guidance going forward.
Dissent — Justice Thomas
Justice Thomas, joined by Justice Gorsuch, would hold that a permit is required only when a point source discharges pollutants directly into navigable waters. He argued that the word 'addition' in the statute means the navigable water must be directly augmented from the point source — not from intervening groundwater — and that this reading best respects Congress's design of leaving groundwater regulation to the states. He criticized the majority's multifactor test as providing almost no usable guidance and would have reversed rather than remanded.
Dissent — Justice Alito
“The Court adopts a nebulous standard, enumerates a non-exhaustive list of potentially relevant factors, and washes its hands of the problem.”Justice Alito's summary objection to the majority's multifactor 'functional equivalent' test as unworkably vague.
Justice Alito argued there are only two textually defensible interpretations of the statute — 'originally from' a point source, or 'directly from' one — and the majority's 'functional equivalent' test is neither. He would have adopted the 'directly from' reading, noting that a broad interpretation of 'point source' (which includes surface ditches and channels) would still capture many indirect discharges without creating the vague, unworkable multi-factor inquiry the majority imposes. He sharply criticized the majority's standard for leaving regulated parties, agencies, and courts unable to predict when a permit is required.
How the Court got there
The legal reasoning, step by step
- The Court focused on the word 'from' in the Clean Water Act's definition of a prohibited discharge: an 'addition of any pollutant to navigable waters from any point source.' The question was how far that word reaches — whether it covers pollution that leaves a pipe, sinks underground, and only later enters the ocean through groundwater.
- The Court rejected the Ninth Circuit's 'fairly traceable' standard as too broad. Modern science can trace pollution through enormous distances and across centuries of underground travel; giving the EPA permit authority over all such discharges would intrude deeply on states' traditional role in regulating groundwater and nonpoint-source pollution — an intrusion Congress deliberately avoided when it declined to include groundwater in the federal permitting program.
- The Court also rejected Maui's and the federal government's position that any intervening groundwater severs the permitting obligation entirely. That reading would create an obvious loophole: a facility could move its pipe back just a few feet from the water's edge to guarantee that some groundwater sits between the discharge and the ocean, defeating one of the Clean Water Act's core regulatory innovations.
- The Court similarly rejected the EPA's 2019 Interpretive Statement, which declared all discharges to groundwater categorically exempt. That reading is inconsistent with the statute's reference to 'any addition' of pollutants to navigable waters, with the inclusion of 'wells' (which typically discharge through groundwater) in the definition of 'point source,' and with a provision requiring states that take over the permit program to maintain authority over disposal into wells.
- Instead, the Court adopted a 'functional equivalent of a direct discharge' standard, asking whether a particular indirect discharge is close enough in effect to dumping straight into navigable waters that Congress would have wanted a permit. Time and distance are the most important factors; others include how much the pollutant is diluted, how it changes in composition, and what fraction of it actually reaches navigable waters. EPA and the courts will refine the standard through guidance and case-by-case decisions.
- Because the Ninth Circuit applied the broader 'fairly traceable' test rather than this functional-equivalence framework, its judgment was vacated and the case sent back for reconsideration under the correct standard.
Doctrinal impact
Cases affected by this decision
Reaffirms Rapanos v. United States (547 U. S. 715)
The majority and Kavanaugh concurrence confirm the Court's ruling adheres to Justice Scalia's Rapanos plurality analysis on point-source permitting.