EPA Releases Draft Guidance on Applying County of Maui Functional-Equivalent Standard

On November 21, 2023, the EPA released draft guidance for applying the U.S. Supreme Court’s 2020 ruling in County of Maui v. Hawaii Wildlife Fund, 140 S. Ct. 1462 (2020) (Maui). 

In Maui, the Hawaii Wildlife Fund and several other environmental groups challenged the County of Maui’s wastewater reclamation facility’s practice of discharging partially treated sewage into groundwater. The polluted water then traveled through groundwater to the Pacific Ocean. The County of Maui asserted that it did not need a National Pollutant Discharge Elimination System (NPDES) permit for this discharge under the Clean Water Act (CWA) because the discharge was not an “addition of any pollutant to navigable waters from a point source.” See 33 U.S.C. § 1311(a); 33 U.S.C. § 1362(12). The environmental groups asserted that this practice by the County of Maui was a discharge of a pollutant to the navigable waters from a point source, for which a permit is required under the Clean Water Act. See 33 U.S.C. § 1311(a); Id. § 1362(12). 

The Maui Court agreed with the petitioners that the discharge was a point source discharge that required an NPDES permit. In doing so, the Court held the CWA could apply to discharges to groundwater that ultimately reached surface water, if the discharge to groundwater was the “functional equivalent” of a discharge to surface water. But the Court acknowledged that not all discharges to groundwater that ultimately reach surface waters would be point source discharges. To determine whether a discharge was the “functional equivalent” of a point source discharge that required a permit under the CWA, the Court identified seven non-exclusive factors that should be considered: “(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, (7) the degree to which the pollution (at that point) has maintained its specific identity.” The Court added that transit time and distance travelled are typically the most important factors.

The EPA’s draft guidance explains how operators of facilities that discharge to groundwater should evaluate whether a discharge to groundwater is the functional equivalent of a direct discharge that requires an NPDES permit.

For the most part, the EPA draft guidance reiterates the Supreme Court’s announcement that the functional equivalent analysis must be done on a case-by-case basis for each facility. The relevance of the factors and the weighing of the relevant factors are both highly depending on site-specific considerations. In some case, the EPA acknowledged, transit time and distance travelled may be the only considerations, whereas in others, more factors may come in. 

The EPA draft guidance explains that the Maui factors should each be examined together and on a continuum. If it takes a long time for the discharge to reach the navigable waters, and/or if the discharge travels a long distance, then the discharge may not be the functional equivalent of a direct discharge. Conversely, if it takes a short time and/or if the discharge travels a short distance, then the discharge may be the functional equivalent of a direct discharge to the navigable waters. Similarly, the EPA draft guidance elaborates that a discharge through a porous subsurface material provides evidence that the discharge may be the functional equivalent of a direct discharge. And a higher mass of pollutant(s) reaching the navigable waters and/or a higher concentration of pollutant(s) reaching the navigable waters similarly provides evidence that the discharge may be the functional equivalent of a direct discharge. Unfortunately, for facility operators seeking certainty about whether their facility might be the functional equivalent of a direct discharge, the EPA draft guidance provides no insight into what distances or travel times are “short” or “long,” how porous subsurface material might be to support a finding that discharge is the functional equivalent of a direct discharge, nor how high the mass or concentration of pollutants might be to support a finding that discharge is the functional equivalent of a discharge to the navigable waters. 
Amid this nebulous guidance, though, the EPA included several specific points. If the spread of pollutants from a source by groundwater moves in a contaminated zone—that is, a plume—it will be important to consider how the plume disperses before the pollutants reach groundwater. If the plume has minimal dispersion before entering a navigable water, that provides evidence that the discharge may be the functional equivalent of a direct discharge. 

The EPA draft guidance also explains that evaluating constituent pollutants may be helpful to the functional equivalence analysis in some situations. A functional equivalent analysis may be based on an analysis of one constituent pollutant when that pollutant is a reasonable indicator for other constituent pollutants. If the analysis indicates that the discharge of an indicator pollutant is the functional equivalent of a direct discharge, then the facility must submit a permit application for that pollutant and the other pollutants with similar characteristics.

And the EPA outlines the information that may be provided for consideration in a functional equivalence analysis, emphasizing that this is merely an illustrative list and that this information is not all needed in any particular case. Potentially helpful information might include: discharge location, transit time, distance travelled, flow characteristics, shallow subsurface geology and hydrology characterization, a description of pollutant-specific dynamics along the groundwater flow path, treatment technologies, effluent characteristics, and an explanation of the permittee’s functional equivalent of a direct discharge analysis, among other information. 

In concluding, the EPA identifies two factors are not relevant to the functional equivalent analysis: intent of the discharger and the existence or lack of a state groundwater protection program. Thus, according to the EPA guidance, it is not a defense to a failure to obtain an NPDES permit that the operator did not intend to pollute the navigable waters, and the existence of a state groundwater protection program does not obviate the need for an NPDES permit.

The EPA’s draft guidance on the application of the functional equivalence standards highlights that facilities that discharge from point sources to groundwater should examine what happens to the discharge after it reaches groundwater and consider whether the discharges might be considered the functional equivalent of a discharge to surface water.