EPA Issues Draft Guidance on Regulation of Groundwater Discharges under Clean Water Act

On December 8, 2020, the U.S. Environmental Protection Agency (EPA) issued draft guidance to clarify the U.S. Supreme Court decision regarding regulation of indirect groundwater discharges to surface water under the Clean Water Act (CWA). This draft guidance intends to assist regulators and the regulated community in determining the need for a National Pollutant Discharge Elimination System (NPDES) permit for existing and new groundwater discharges that may discharge into navigable waters.  Overall, the draft guidance is vague, providing little clear direction for implementation and leaving many legal and technical questions unanswered.

Background

In April 2020, the U.S. Supreme Court decided in County of Maui, Hawaii, v. Hawaii Wildlife Fund et al. (Maui) that an NPDES permit is required “where there is a direct discharge from a point source into navigable waters or where there is a functional equivalent of a direct discharge.”  The decision did not define “functional equivalent,” and the court recognized that it could not clearly define what discharges would be regulated, but acknowledged that the primary factors to determine if an NPDES permit would be required for a groundwater discharge would be travel, time, and distance from the point of discharge to the waterway.  Other factors that would be used to determine CWA jurisdiction include:

• The nature of material through which the pollutant travels
• Extent of dilution or chemical change of the pollutant
• Amount of pollutant entering the navigable water relative to the amount discharged
• The area over which, or the means by which, a pollutant enters the waters
• The degree to which the pollutant can be identified.

The opinion anticipated that EPA could provide administrative guidance such as grants of individual permits, promulgation of general permits, or the development of general rules.

The Draft Guidance

The draft guidance articulates three concepts to support clarification of the Maui decision:

1. 1. An actual discharge of a pollutant to a waters of the United Stated (WOTUS) is the threshold condition that triggers the evaluation for the need for an NPDES permit.
2. 2. The discharge of pollutants that reach a WOTUS must be from a point source to trigger a need for an NPDES permit.
3. 3. The system design and performance should be considered in the evaluation of functional equivalent.

EPA’s draft guidance cites the court decision clarifying that the CWA requires an actual discharge, and “…not potential discharges, and certainly not point sources themselves.”  Although a threshold condition, the release of a pollutant from a point source is not sufficient to trigger NPDES permitting requirements.  Example scenarios in which EPA recommends considering the need for a technical evaluation include discharges of highly mobile pollutants from a point source into sandy soils or into shallow groundwater near a WOTUS.   The evaluation would support determination of the occurrence of an actual discharge and the functional equivalence of the groundwater discharge to a direct discharge.  However, the draft guidance does not provide specific metrics by which to judge the evaluation.

The second threshold condition to trigger potential NPDES permit requirements is that the groundwater discharge is from a point source.  The guidance reiterates the CWA point source definition as “…any discernable, confined and discrete conveyance…” The draft guidance offers no examples or defining tests for identification of release from a point source.

Once an actual discharge from a point source has been demonstrated, a functional equivalent evaluation would then be performed to determine permitting requirements.  The time and distance traveled by the discharge to reach a WOTUS, as well as any changes to the pollutant as it travels, such as uptake or dilution would be evaluated.  Changes in pollutant concentration or composition as it travels through groundwater could lead to a finding that the discharge is not a functional equivalent of a direct discharge.  A groundwater discharge reaching a WOTUS with similar or the same chemical concentration and composition “…may be more like a direct discharge to the jurisdictional water.”  Again, the draft guidance does not provide any specific evaluation parameters to support determination of functional equivalence.

Finally, EPA proposed that the system design and performance be considered as an additional factor, in addition to the seven factors identified by the Supreme Court, for determination of a functional equivalent direct discharge.  If a facility or system includes storage, treatment, attenuation, and/or dilution that may change the pollutant or the amount of pollutant entering a WOTUS, “…it may be less likely that an NPDES permit would be required.”  Examples of such systems provided in the draft guidance are septic systems, cesspools, or settling ponds. Conversely, if a facility or system “consistently and predictably” discharges pollutants through groundwater and into a WOTUS, a permit may be required.

Conclusion

This draft guidance intends to provide a starting point to determine the need for NPDES permit for an indirect groundwater discharge into a WOTUS, but overall the guidance is vague, with no clear direction for application.  Several determining factors remain undefined (e.g., travel times or extent of pollutant change that trigger a permit requirement), and significant legal and technical implementation questions remain.  Time will tell the fate of the draft guidance, which is clearly in question with the upcoming change in administration.

The draft guidance will be published in the Federal Register, followed by a 30-day public comment period.  Read the draft guidance.

For further information on Integral’s range of services to assist clients in evaluating groundwater–surface water interactions and CWA regulations, contact Marcia Greenblatt at mgreenblatt@integral-corp.com.