Previous Article
Next Article

Your authoritative, multi-channel network for natural resources and environmental information since 1989 – by practioners for practitioners.

Line Spacing+- AFont Size+- Print This Article Back To Homepage

U.S. EPA Finalizes Guidance on Implementation of Supreme Court’s ‘Functional Equivalent’ CWA Test in County of Maui Case

U.S. EPA Finalizes Guidance on Implementation of Supreme Court’s ‘Functional Equivalent’ CWA Test in County of Maui Case
Related Articles

By Nicole Granquist, Meghan Quinn and Meredith Nikkel

On January 14, 2021, the U.S. Environmental Protection Agency (EPA) finalized guidance regarding the implementation of the U.S. Supreme Court’s decision in County of Maui, Hawaii v. Hawaii Wildlife Fund, 590 U.S. ___ (2020) (Maui), which established a “functional equivalent” test to determine when discharges to groundwater that ultimately reach surface waters should be regulated under the federal Clean Water Act in the same manner as a direct discharge to surface waters (Maui Guidance). The Maui Guidance states that any discharge must meet certain “baseline permitting principles” comprised of threshold conditions that trigger the National Pollutant Discharge Elimination System (NPDES) Permit requirement, and the type of analysis permit writers currently conduct for surface water discharges. In doing so, the Maui Guidance sets forth an additional factor that should be evaluated when determining whether a discharge to groundwater requires an NPDES Permit—“the design and function of the treatment system”—and provides  guidance regarding the types of discharges and associated treatment systems for which NPDES Permits will not be required.

Background—The Maui Decision

In Maui, the Supreme Court held that an NPDES permit is required “if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters.” According to the Court, evaluation of whether a discharge of a pollutant to groundwater is the “functional equivalent of a direct discharge from the point source into navigable waters,” requires the application of the following seven factors: 1) the pollutant’s travel time between the discharge point and the navigable water; 2) the distance traveled; 3) the material through which the discharge travels; 4) dilution or chemical changes during travel; 5) the amount of pollutant entering the navigable water as compared to the amount that leaves the point source; 6) the way or location the pollutant enters the navigable water; and 7) the degree to which the pollution has retained its identity upon reaching the navigable water. The opinion makes clear that the list is not exhaustive, but notes that time and distance may be the most important factors. (See:

The Maui Guidance Summary

The primary focus of the Maui Guidance appears to be a reduction in the number of inquiries from the regulated community regarding whether or not an NPDES Permit is required for a particular discharge. To eliminate a number of those inquiries, the Maui Guidance describes “baseline permitting principles” that seek to resolve questions from the regulated community (and potentially frivolous litigation). The baseline permitting principles, which consume the majority of the eight-page guidance memorandum, are primarily a recitation of the elements that traditionally trigger the NPDES Permit requirement as applied to surface waters.

By confirming that all discharges are subject to the described framework, the EPA adopts an additional factor that:

. . .may prove relevant and thus should be considered when performing a ‘functional equivalent’ analysis: the design and performance of the system or facility from which the pollutant is released.

The Maui Guidance indicates that an evaluation of the design and performance of the facility or system from which a pollutant is released is customary when the agency evaluates whether a direct discharge requires an NPDES Permit. The Maui Guidance goes one step further by describing treatment system designs and discharge point locations that are unlikely to be subject to the NPDES Permit requirement, as well as the influence of such system component designs and locations on the composition of any pollutants discharged to groundwater that ultimately reach surface water. For example:

. . .the point of discharge may be engineered to direct the pollutant into a subsurface aquitard or to a surface area designed to slow the transit time of a pollutant that ultimately reaches a water of the United States.

EPA also clarifies that the agency anticipates that the issuance of NPDES Permits for discharges of pollutants to groundwater:

. . . will continue to be a small percentage of the overall number of NPDES permits issued following application of the Supreme Court’s ‘functional equivalent’ analysis.

To emphasize this point, the Maui Guidance reminds practitioners that: 1) the discharge must first meet the threshold requirements that trigger the NPDES Permit requirement; and 2) all of the factors comprising the “functional equivalent” test must be applied to the discharge. In other words, a demonstration that pollutants associated with a point source discharge merely reach surface waters falls short of the analysis required by the Maui decision, and would not trigger the NPDES Permit requirement for discharges to groundwater.

Conclusion and Implications

The Maui Guidance provides insight into how the EPA will apply its current NPDES Permit program framework to groundwater discharges, confirmed by the establishment of the new “design and performance” factor. Moreover, the Maui Guidance crafts a distinction between the Ninth Circuit’s “fairly traceable” standard and the Supreme Court’s “functional equivalent” test by indicating that the fact that a pollutant associated with a point source discharge to groundwater reaches surface waters is not enough to trigger NPDES Permitting.

However, whether the Maui Guidance will remain in effect is unclear, given the Biden Administration’s recent adoption of the Executive Order on Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis, which will require EPA to revisit all “regulations, orders, guidance documents, policies, and any other similar agency actions (agency actions) promulgated, issued, or adopted between January 20, 2017, and January 20, 2021” that may be inconsistent with the Biden administration’s policy on environmental protection and public health. The outcome of that review process remains to be seen. For more information about the Guidance, see: