Underground Pathways to Pollution: The Need for Better Guidance on Groundwater Hydrologically Connected to Surface Water

In 2018, the Fourth, Sixth, and Ninth Circuits addressed whether groundwater with a sufficient hydrological connection to navigable surface water should fall within the scope of the Clean Water Act. In two simultaneously released decisions, the Sixth Circuit held that the Clean Water Act does not apply to hydrologically connected groundwater. Conversely, the Fourth and Ninth Circuits agreed that the Clean Water Act does cover hydrologically connected groundwater. However, the Fourth and Ninth Circuits took two distinct approaches when coming to their decisions. The Fourth Circuit evaluated whether or not there was a “direct hydrological connection”—a legal standard previously endorsed by the Environmental Protection Agency—between the point source and the affected surface waters. The Ninth Circuit created its own legal test, which requires that pollutants be “fairly traceable” to the point source and present at a “more than de minimis” amount in order to fall within the scope of the Clean Water Act. In February 2019, the Supreme Court granted certiorari to the Ninth Circuit’s case to determine whether hydrologically connected water is covered by the Clean Water Act, which took the debate out of the agency’s hands. In order to have prevented this issue from being left to courts to decide, environmental groups should have lobbied the Environmental Protection Agency to promulgate a rule during an environmentally-friendly administration. Regardless, if the Ninth Circuit’s case is affirmed, the Environmental Protection Agency should still promulgate a rule expanding upon the Ninth Circuit decision that clearly states that hydrologically connected groundwater is covered by the Clean Water Act and provides guidelines for determining the extent of groundwater connectivity. This Note suggests that such a rule should adopt the Ninth Circuit’ s legal test, consider scientific techniques for determining connectivity, and suggest different guidelines for beneficial water reuse projects.