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December 15, 2020  |  Written by J. Palmer Hilton

USEPA Issues Draft Guidance to Clarify the U.S. Supreme Court’s Maui Decision Regarding Permit Requirements for Discharges to Groundwater That Reach Waters of the United States

On December 8, 2020, the United States Environmental Protection Agency (EPA) issued draft guidance intended to clarify when a National Pollutant Discharge Elimination System (NPDES) permit is required under the Clean Water Act (Act) based upon the recent United States Supreme Court ruling in County of Maui v. Hawaii Wildlife Fund (Maui).  This guidance is important for public agencies and other entities that make point source discharges to groundwater that reach waters of the United States.  If the draft guidance is finalized, it will serve as administrative guidance for both permit writers and regulated entities in ensuring compliance with the requirements of the Act.

In the Maui decision, the Supreme Court held that the Act’s permitting requirements may be used to regulate pollution traveling through groundwater and created a new test for when a NPDES permit may be required.  Until this decision, federal courts were divided on the issue of whether pollutants discharged from point sources could be regulated under the Act if they traveled through groundwater.  The test established in Maui requires a permit for a discharge of pollutants from a point source if, after traveling through groundwater, that discharge reaches “waters of the United States,” and if that discharge is a “functional equivalent of a direct discharge from the point source into navigable waters.”  The Supreme Court also identified a non-exclusive set of seven factors to consider to determine whether a discharge from a point source is a “functional equivalent” of a direct discharge.  These factors include: (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.

The EPA’s draft guidance aims to clarify this Supreme Court decision by applying the “functional equivalent” test to the EPA’s NPDES permit program and identifying additional factors that permit writers and regulated entities should consider when evaluating the need for an NPDES permit for pollutant discharges.  The guidance makes clear that the threshold conditions requiring an NPDES permit are not modified by the Maui decision.  Those necessary conditions are:  (1) a discharge of pollutants from a point source; and (2) that reaches a water of the United States.  The guidance explains that the Maui decision imposes NPDES requirements on an additional subset of discharges that travel through groundwater, but only those discharges that are the “functional equivalent” of direct discharges.

If there are indications that a discharge traveling through groundwater may reach waters of the United States, the EPA suggests dischargers conduct a technical analysis examining hydraulic conductivity based on soil and pollutant type.  This technical analysis should consider the seven factors listed above in drawing a conclusion as to whether the discharge is the “functional equivalent” of a direct discharge.

The draft guidance was published in the Federal Register on December 10, 2020, and is available for public comment until January 11, 2021.  A copy of the draft guidance in the Federal Register is available here.

For additional information on this draft guidance, and Clean Water Act issues, please contact Palmer Hilton at or 916-446-7979.

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