Skip to main content
Environmental Edge
May 11, 2021

What’s up With Maui? One Year After the SCOTUS Decision on the Clean Water Act and Groundwater Discharges, Significant Uncertainty Remains

Environmental Edge: Climate Change & Regulatory Insights

Discharges directly into groundwater are generally not covered by the Clean Water Act, but for years, there was confusion about whether the Act applies to discharges to groundwater, where the groundwater has a direct hydrological connection to surface waters. The courts were split, and EPA argued both sides of the issue. In April 2020, in County of Maui v. Hawaii Wildlife Fund, the Supreme Court announced a seemingly major expansion of the Act, holding that it applies “if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters.”

SCOTUS identified a non-exclusive list of seven factors to determine “functional equivalency,” giving presumptive predominance to the first two factors: “(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, [and] (7) the degree to which the pollution (at that point) has maintained its specific identity.” SCOTUS provided little guidance on how the “functional equivalency” factors should be applied, and the decision left most scratching their heads as to the practical implications.

On January 14, 2021, the Trump EPA issued a Guidance Memorandum on applying the Maui “functional equivalency” test, taking a narrow view of when a Clean Water Act NPDES permit is required under SCOTUS’s seven factors and adding an eighth factor: “the design and performance of the system or facility from which the pollutant is released.” The Guidance Memo was short on specifics and seemingly made the “functional equivalency” test even more complicated.

Although the Biden Administration has been eager to reverse policies put in place by the Trump Administration, it has not yet publicly turned its attention to the dilemma created by Maui and the Trump EPA’s 11th hour Guidance Memo. The Biden EPA may withdraw the Trump EPA’s Guidance and replace it with guidance or a rule taking a broader view of when an NPDES permit is required for discharges to groundwater hydrologically connected to surface waters. The Biden Administration might also seek to direct some infrastructure funding to dealing with the issue of groundwater discharges. In the meantime, the states, which in most cases are left to implement Maui through their federally delegated NPDES permitting authorities, but have yet to receive any additional resources to address indirect discharges, are likely to resort to issuing general permits for many groundwater discharges.

We are continuing to monitor post-Maui developments. Please contact us with any questions.

© Arnold & Porter Kaye Scholer LLP 2021 All Rights Reserved. This blog post is intended to be a general summary of the law and does not constitute legal advice. You should consult with counsel to determine applicable legal requirements in a specific fact situation.