On Feb. 1, 2018, the U.S. Court of Appeals for the Ninth Circuit issued a highly anticipated decision in Hawai’i Wildlife Fund v. County of Maui, No. 15-17447 (9th Cir. Feb. 1, 2018). At issue was whether the County of Maui (“County”) required a Clean Water Act (“CWA”) permit to dispose of wastewater through groundwater discharge wells where the discharge waters ultimately reach the Pacific Ocean. Although many states require permits for discharges to groundwater, the CWA does not cover groundwater. The holding increases federal permit requirements for a variety of entities, including those that discharge wastewater through groundwater disposal wells and those that detain stormwater and allow it to infiltrate to groundwater, which may eventually reach surface waters.