In County of Maui v. Hawaii Wildlife Fund, the City of Maui pumps treated water from the wastewater reclamation facility into the groundwater through wells. The effluent then travels about a half mile through groundwater to the Pacific Ocean. The question was whether the Clean Water Act “requires a permit when pollutants originate from a point source but are conveyed to navigable waters by a nonpoint source,” here, groundwater. The Ninth Circuit had concluded that a permit was required here because the “pollutants are fairly traceable from the point source to a navigable water.” 886 F.3d 737, 749.
The Supreme Court vacated the Ninth Circuit’s decision. In doing so, it rejected the various bright line tests proposed by the parties and amicus curiae and opted for a weighing-of-factors approach, similar to the approach in other CWA disputes (e.g. definition of “navigable waters”). The Supreme Court stated that the CWA requires a permit for a direct discharge or when there is “the functional equivalent of a direct discharge.” The Supreme Court provided the following guidance for making the determination:
Many factors may be relevant to determining whether a particular discharge is the functional equivalent of one directly into navigable waters. Time and distance will be the most important factors in most cases, but other relevant factors may include, e.g., the nature of the material through which the pollutant travels and the extent to which the pollutant is diluted or chemically changed as it travels. Courts will provide additional guidance through decisions in individual cases.
While the Supreme Court agreed that there can be situations where a discharge through groundwater could be subject to NPDES permitting as a discharge to waters of the US from a point source, it did not agree that the discharge in this case required a permit after evaluating the facts for “functional equivalence.”
Despite resolving the split among the Circuit Courts, the Supreme Court’s essentially common law approach to further defining what may be a “functional equivalent of a direct discharge” likely will not reduce disputes over whether a discharge is regulated under the CWA. Instead, it opens a field of questions to be answered by various NPDES permitting agencies and permit holders.