U.S. Supreme Court’s New Discharge to Groundwater Decision is County of Maui Raises More Questions than it Answers
California Water Law & Policy Reporter, Volume 30, Number 9
On April 23, 2020, the United States Supreme Court (“Supreme Court”) issued a 6-3 decision in County of Maui, Hawaii v. Hawaii Wildlife Fund, 590 U.S. ___ (Apr. 23, 2020) setting forth a new test for determining when a point source discharge to groundwater, that ultimately reaches a navigable surface water, is subject to the federal Clean Water Act’s National Pollutant Discharge Elimination System (NPDES) permitting requirement. The U.S. Supreme Court held that an NPDES permit is required “if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters.” The Supreme Court lists several factors that may be used in determining whether a discharge through groundwater represents the “functional equivalent,” but notes that the list is not exhaustive. Additionally, the Supreme Court did not apply this new rule to the facts in County of Maui, leaving the practical application of this rule unanswered.