Clarity Provided for New “Functional Equivalent” Test

Today, the U.S. Environmental Protection Agency published guidance on how to apply the U.S. Supreme Court’s decision in County of Maui v. Hawai’i Wildlife Fund. The guidance provides some clarity as to when a discharge to groundwater is the “functional equivalent of a direct discharge from a point source into navigable waters.”

The Court’s decision in Maui held that a discharge of pollutants to groundwater will be subject to the Clean Water Act’s permitting requirements if it is the “functional equivalent” of a direct discharge to surface waters. The EPA’s guidance reviews the criteria established in the case and adds an additional factor for determining whether a discharge will qualify – “the design and performance of the system or facility from which the pollutant is released.”

The guidance is limited and straightforward, detailing the fundamental criteria for a discharge to qualify:

• The pollutants at issue must actually reach surface waters that are subject to the Clean Water Act,
• The pollutants must have been discharged from a “point source” in the first place and
• The pollutants need to flow through the groundwater in a manner and at a speed that is the functional equivalent of a direct discharge.

The draft guidance will be available for public comment for 30 days (Docket No. EPA-HQ-OW-2020-0673). The EPA may pursue a future rule to provide greater regulatory certainty.

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