In 2020, the U.S. Supreme Court issued a ruling in a Clean Water Act (CWA) citizens’ suit against the County of Maui. County of Maui v. Hawai’i Wildlife Fund, 140 S. Ct. 1462 (2020). The plaintiffs claimed that the County of Maui’s wastewater reclamation facility discharged pollutants through groundwater into a navigable water in violation of the CWA. The Court ruled that a permit is required when there is “the functional equivalent of a direct discharge” and remanded the case for further proceedings.

On remand, the plaintiffs moved for summary judgment. The County of Maui claimed that the plaintiffs’ motion relied on a flawed 2013 groundwater tracer study. Arguing that the study was unreliable, the County of Maui petitioned for a pretrial evidentiary hearing. In denying the motion, the court ruled that there was no reason to decide the issue in advance of considering the pending summary judgment motion. The plaintiffs asserted that they did not rely on the study in their motion for summary judgment. The court stated that while it must perform a gatekeeping function to ensure that admitted scientific evidence is relevant and reliable, a pretrial evidentiary hearing was not necessary. The court noted that it might turn out that the court could perform its gatekeeping function when the disputed evidence is offered during the bench trial, which is scheduled for the fall. The case could also be decided on summary judgment without a trial.

Hawaii_Wildlife_Fund_v._County_of_Maui, 2021 WL 1299192 (D. Haw. April 7, 2021).