On February 20, 2018, the U.S. Environmental Protection Agency (EPA) requested comments on whether pollutant discharges from point sources that reach jurisdictional surface waters via groundwater or other subsurface flow with a direct hydrologic connection to the jurisdictional surface water may be subject to regulation under the Clean Water Act (CWA).

The answer to this question will have far reaching implications because the scope of the agency’s powers under the CWA determines the scope of:

  • National Pollutant Discharge Elimination System (NPDES) permitting programs;
  • Section 404 wetlands permitting programs;
  • Section 311 oil/hazardous substance release requirements; and
  • Spill Prevention Control and Countermeasure (SPCC) requirements.

As a result, the extent to which a discharge to groundwater that reaches jurisdictional surface waters is subject to regulation under the CWA is a significant issue for farmers, manufacturers, and anyone who discharges to groundwater.


The CWA regulates the discharge of pollutants and placement of fill into “navigable waters,” and defines navigable waters as “the waters of the United States.” Since the CWA was passed in 1972, there has been much debate over the extent to which waters that are not considered navigable in fact and wetlands may be regulated as waters of the United States. This uncertainty has given rise to a variety of CWA citizen suits alleging that discharges from point sources that migrate via groundwater to waters of the United States require NPDES permits.

Over the years, various federal courts have reached differing conclusions on the question of whether discharges to groundwater can be considered discharges to waters of the United States. Most recently, the Ninth Circuit addressed this issue in Hawaii Wildlife Fund v. County of Maui, 881 F.3d 754 (9th Cir. 2018). In that case, the County of Maui (the “County”) discharged treated effluent from its wastewater reclamation facility into injection wells. Tracer dye studies confirmed that this effluent migrated through the groundwater to the Pacific Ocean. A three-judge panel for the Ninth Circuit Court of Appeals ruled that the County’s discharge triggered Clean Water Act jurisdiction and the need for an NPDES permit because the groundwater was hydrologically connected to the Pacific Ocean, a water of the United States. Under the court’s ruling, an indirect discharge of contaminants from point sources that travels through groundwater and ultimately reaches navigable waters will now be subject to federal permitting requirements.

EPA Request For Comments

In prior rulemakings, permitting, and guidance documents, EPA has stated that pollutants discharged from point sources to jurisdictional surface water via groundwater or other subsurface flow that has a direct hydrologic connection to the surface water may be subject to CWA permitting requirements. Similarly, in the recent Federal Register notice, EPA characterizes the case law on this issue as “mixed.” Consequently, EPA requests comment on whether it should clarify its position on this issue to provide certainly for the public and the regulated community.  EPA also requests comment regarding:

  • Whether EPA has authority to permit such releases under the CWA;
  • Whether such releases are adequately addressed through existing state statutory or regulatory programs or existing federal programs; and
  • If EPA has the authority to permit such releases, whether EPA should clarify what activities could be regulated and which connections could be considered direct.

Comments on the proposed clarification must be received on or before May 21, 2018.

What This Means to You

In practice, underground injection wells have not typically been subject to NPDES permitting requirements. Instead, groundwater is typically regulated by states and is often subject to state permits. As a result, farmers, manufacturers, and anyone who conducts activities that release pollutants to groundwater may be affected by whether and how EPA clarifies its position regarding when or if direct hydrologically connected releases are subject to regulation under the CWA.

Contact Us

Our environmental attorneys can help potentially affected entities respond to EPA’s request for comments. For more information on how this may impact your operation, please contact a member of Husch Blackwell’s Environmental team.