Legal Alert: U.S. Supreme Court Holds Clean Water Act Permit Needed for Discharges through Groundwater to Navigable Waters

On April 23, 2020, the United States Supreme Court, in a 6-3 opinion, in County of Maui, Hawaii v. Hawaii Wildlife Fund et al.*, resolved a split of opinions by lower courts and ruled the federal Clean Water Act (CWA) can regulate discharges of pollutants through groundwater that end up in surface waters of the United States.  The Court held a CWA permit is required “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 CWA prohibits the addition of any pollutant to navigable waters from any point source without a permit.  A “point source” is defined by the law to be any discernible, confined and discrete conveyance from which pollutants are or may be discharged, including, e.g. any container, pipe, ditch, channel, tunnel, conduit, or well.  The CWA defines “navigable waters” only as “waters of the United States” (WOTUS), and includes navigable streams, rivers, oceans, coastal waters and certain wetlands.  The definition of WOTUS has been the subject of much controversy and litigation over the years, and resulted in the re-issuance of the definition of the WOTUS rule by U.S. EPA and the Army Corps of Engineers on April 21, 2020.  

In this case, the County of Maui discharged about four million gallons per day of partially treated wastewater from a wastewater treatment plant into four wells, which pollutants traveled about one half mile through the groundwater to the Pacific Ocean.  The State of Hawaii agreed with Maui County that it did not need a CWA permit to discharge the wastewater into the groundwater even though some of the pollutants reached the ocean.  In 2012, environmental groups sued asserting the County violated the CWA by discharging pollutants from a point source into navigable waters (Pacific Ocean) without a CWA permit. 

The federal District Court found the discharge of pollutants from Maui’s wells into the groundwater which traveled to the ocean was functionally a discharge into navigable water that required a CWA permit.  On appeal, in 2018, the federal Ninth Circuit Court of Appeals affirmed and held a CWA permit is required when pollutants are “fairly traceable” from a point source such that it was the functional equivalent of a direct discharge into navigable waters.  The Court held a permit was needed since:  (1) the pollutants were discharged from a point source, i.e. injection wells; (2) the pollutants were fairly traceable from a point source to a navigable water; and (3) more than a de minimis amount of pollutants from the point source reached the navigable waters.

Shortly thereafter, in 2018, the federal Fourth Circuit Court of Appeals held a CWA permit is required to discharge pollution traveling through groundwater to navigable waters.  In contrast, in 2018, the federal Sixth Circuit Court of Appeals held the CWA does not regulate pollution that travels through groundwater or any other indirect route to reach navigable water.  Then, in 2019, prior to the re-issuance of the revised WOTUS rule, the U.S. EPA issued an “Interpretive Statement” asserting the CWA excludes “all releases of pollutants from a point source to groundwater regardless of a hydrologic connection between the groundwater and the jurisdictional surface water.”

Supreme Court’s Ruling

The County and the U.S. Solicitor General argued a point source must discharge pollutants directly to a navigable water to be regulated under the CWA and that the discharge of the pollutants into a nonpoint source such as groundwater was not a CWA-regulated discharge.  The environmental groups argued a CWA permit was required if the pollutant could be fairly traceable to a point source regardless of the distance and media it traveled through.

The Supreme Court rejected both arguments and adopted a more middle ground by finding the CWA’s permitting requirements only cover discharges through groundwater that are the “functional equivalent” of a direct discharge to surface (navigable) waters. This functional equivalency occurs when the discharge reaches the same result through similar means as when a point source directly discharges into navigable waters.  In not establishing a bright-line rule, the Court identified various nonexclusive factors for defining what constitutes a “functional equivalent” discharge, including:

  1. Transit time.
  2. Distance traveled.
  3. Nature of 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 that enters the navigable water relative the amount that leaves the point source.
  6. The manner by which the pollutant enters the navigable water.
  7. The degree to which the pollutant maintains it specific identity.

The Court acknowledged the limitations of its approach, but left it to lower courts to provide guidance through individual cases and for EPA to provide administrative guidance as to what indirect discharge is the functional equivalent of a direct discharge to WOTUS.


The absence of clear-cut guidance from the Court as to what constitutes functional equivalent of a direct discharge will likely create uncertainty and ambiguity, and give rise to additional litigation over the coming years as to whether various types of indirect discharges to groundwater that reach navigable waters will be subject to CWA permitting requirements.  

In light of the Court’s Maui decision, entities that operate wastewater treatment facilities or wastewater storage lagoons, injection wells, landfills, other types of waste management units and remediation projects may need to evaluate the need for CWA discharge permits, particularly if they are located somewhat near navigable waters.  It’s possible such types of facilities could be subject to citizen suits under the CWA for failing to hold a CWA permit for indirect discharge to WOTUS.  

It may take some time for state regulatory agencies to work through this ruling to determine how to structure CWA discharge permits and associated effluent limits for indirect discharges. One work-around approach may be the issuance of a general CWA permit for these types of discharges. 

Should you have any questions please contact Brian Babb at 513.579.6963 or 

KMK Law articles and blog posts are intended to bring attention to developments in the law and are not intended as legal advice for any particular client or any particular situation. The laws/regulations and interpretations thereof are evolving and subject to change. Although we will attempt to update articles/blog posts for material changes, the article/post may not reflect changes in laws/regulations or guidance issued after the date the article/post was published. Please consult with counsel of your choice regarding any specific questions you may have.


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