Clean Water Act Compliance: Court Rulings Raise Questions on Groundwater Discharges Regulation
May 10, 2018

Little AndroscogginTwo recent court rulings have expanded the reach of the Clean Water Act (CWA) to include regulation of indirect groundwater discharges to surface water. Both waste discharges and unintentional releases are subjects of these rulings, potentially resulting in additional regulatory burden and violations for existing operations previously considered compliant. These rulings may spur the need to characterize groundwater–surface water interactions and evaluate potential water quality impacts.

Litigation SupportThe 2018 rulings involving interpretation of the CWA could change the way groundwater discharge is regulated. Although the CWA has always required a National Pollutant Discharge Elimination System (NPDES) permit for a point source pollutant discharge into waters of the United States, in most cases, groundwater is not considered a water of the U.S., and has not generally been subject to the CWA. However, rulings in recent cases found that groundwater discharging into surface waters should be regulated under the CWA. These rulings raise considerable technical and regulatory challenges, and the legal implications remain unclear—although the recent rulings suggest that regulation of discharges and releases to groundwater can be enacted under the CWA.

In a matter in Hawaii, the court ruled in March 2018 that treated wastewater that had been injected into four groundwater wells and eventually seeped into the Pacific Ocean constituted a point source and is subject to NPDES permitting requirements1. A dye study performed by the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers showed a hydraulic connection between the wells and the ocean, with water from two of the three wells tested reaching the ocean in 84 days. The court found that the discharged pollutants constituted a point source and were traceable from that point source to navigable waters at levels sufficient to require regulation under the CWA.

In April 2018, the court found liability under the CWA following a pipeline rupture that resulted in an indirect petroleum discharge to an adjacent waterway2. The pipeline was repaired, and remediation and removal activities were performed. The ruling stated that although the point source of the pollutants (the ruptured pipeline) had ceased, sufficient pollutants were reaching nearby creeks and wetlands that claims were covered under the CWA.

The technical challenges posed by regulation of indirect groundwater discharges to waters of the U.S. could be substantial, including establishment of a hydraulic connection and definition of the regulated area over which the groundwater is discharging into surface water. From a regulatory perspective, it is not clear what discharges could be regulated under the CWA. EPA issued a Request for Comments regarding regulation of direct hydraulic connection of groundwater to jurisdictional surface water under the CWA. Integral will continue to follow these and related matters to stay current on the technical, regulatory, and legal issues and implications of these rulings. Our hydrologists, water resources engineers, compliance specialists, and other multidisciplinary staff can help clients prepare for potential changes in CWA enforcement. For further information on Integral’s range of services to assist clients in evaluating groundwater–surface water interactions and CWA regulations, contact Marcia Greenblatt, Ph.D., at

More Information:
Read The Water Report article
EPA Request for Comments
Integral 2015 CWA news brief

1Hawaii Wildlife Fund et al. v. County of Maui

2Upstate Forever v. Kinder Morgan Energy Partners