In 2019, the U.S. Supreme Court’s decision in County of Maui V. Hawaii Wildlife Fund addressed when a permit is required under the Clean Water Act for discharges to groundwater.  Prior to Maui, it was a long standing debate as to when the Clean Water Act (CWA) in order to discharge to groundwater.  Traditionally, impacts to groundwater itself was outside the regulatory scope of the Clean Water Act.  The Court ruled, that in certain circumstances, a CWA permit was needed for discharges to groundwater.  Specifically, the Court ruled, a permit is needed when such discharges equate to the “functional equivalent” of a discharge to federally protected surface water (larger rivers, lakes or the ocean).

The Court’s ruling opened the door that NPDES CWA Permits may be needed for such things as:

  • Wastewater treatment systems with drain fields or that directly discharge to the subsurface;
  • Impoundments that may not be lined and leaching to groundwater;
  • Stormwater management practices that resulted in discharges to groundwater;
  • Leaks from storage tanks or subsurface piping that results in pollutants reaching groundwater;
  • Or other equipment, systems or practices that resulted in the discharge of pollutants to groundwater.

The Court established a somewhat vague standard for determining when a discharge was functionally equivalent to a direct discharge to surface water.  The “Functional Equivalent Test” established by the Court included the following factors to be considered on a case-by-case basis:

  1. How long do pollutants discharged to groundwater take to reach surface water;
  2. How long of a distanced do those pollutants discharged need to travel to reach surface water;
  3. The nature of the material through which the pollutants travel to reach surface water;
  4. The extent to which pollutants are diluted or change chemically as it travels and reach surface water;
  5. The amount of pollutants that reach surface water compared to the amount that was discharged from the point source of pollution;
  6. The manner by or area in which the pollutant enters surface water; and
  7. The degree to which the pollution, once it reaches surface water, has maintained its specific identity.

The Court noted that time and distance traveled would likely be the most important factors in the case-by-case analysis under the Functional Equivalent Test.

As with similar case-by-case tests for making regulatory determinations, implementation can be fraught with inconsistencies and variations in how the factors are evaluated region to region or even regulatory office to regulatory office.  This is why the Court indicated in its decision that EPA could provide administrative guidance to help ensure consistent application of the Functional Equivalent Test.

On January 14, 2021, the Trump Administration’s EPA finalized guidance called Applying the Supreme Court’s County of Maui v. Hawaii Wildlife Fund Decision in the Clean Water Act Section 402 National Pollutant Discharge Elimination Permit ProgramMany commentators viewed the guidance as an attempt to narrowly apply the Functional Equivalent Test in order to limit federal regulatory jurisdiction.  Perhaps the guidance document’s most controversial component was that, in applying the Functional Equivalent Test, EPA should consider the design and performance of the system discharging the pollutants.  For example, the more the design and performance of the system increased the distance pollutants needed to travel or the amount of time it took for pollutants to reach surface water, the less likely a permit would be required.  It was almost as if the intent of the system’s design would be evaluated under the guidance.  If the system wasn’t intended to have a discharge of pollutants to groundwater that reached surface water, then a permit would not be required.  

On September 15, 2021, the Biden administration announced it was rescinding the Trump administration’s guidance.   In rescinding the guidance, EPA stated that the Trump era guidance “added a new factor” to the Functional Equivalent Test which was inconsistent with the Court’s ruling (i.e. considering the design and performance of the system from which the pollutant was released).  By rescinding the guidance, the Biden Administration clearly intends to require CWA permits in more cases.  However, it is unclear whether the Biden Administration intends to develop its own guidance document to try an ensure consistent application of the case-by-case analysis.  In the meantime, the Functional Equivalent Test is likely to be prone to more inconsistent application.  Such regulatory uncertainty also typically leads to more litigation.