On March 4, 2025, the U.S. Supreme Court ruled that the federal Clean Water Act does not authorize the inclusion of some nonquantifiable water quality standards in National Pollutant Discharge Elimination System (“NPDES”) permits. NPDES permits are generally required for discharges of pollutants to most waterways. While authorized by the Clean Water Act and overseen by the U.S. Environmental Protection Agency (“EPA”), in Pennsylvania, NPDES permits are generally issued by the Pennsylvania Department of Environmental Protection (“DEP”).

The case, City and County of San Francisco v. EPA, before the Supreme Court involved a challenge by San Francisco to terms included in its NPDES permit for its sewer and wastewater system. The City alleged that certain permit conditions were too vague and difficult to comply with. NPDES permits generally include both specific numerical and narrative standards. One provision in San Francisco’s permit at issue before the Court prohibited any discharge that “contributes to a violation of any applicable water quality standard” for receiving waters. Another challenged provision prohibited the City from performing any treatment or making any discharge that “creates pollution, contamination, or nuisance.” The Court held that these types of “end-result” standards lacked the specificity needed to achieve compliance with the Clean Water Act.

The Court’s ruling brings into question the validity of similar “end-result” or narrative standards included in NPDES permits. In addition, the decision in this case may provide a viable defense to permittees subject to enforcement actions by EPA or DEP related to such permit conditions. Parties seeking NPDES permits from DEP or who are subject to enforcement actions should consult with environmental counsel to discuss the implications of this Supreme Court decision.

The Court’s ruling is likely to lead to EPA and Pennsylvania DEP reevaluating many conditions now routinely included in NPDES permits, including those used to control stormwater during construction activities. Permit applicants may likely face delays in the permit review process, especially in light of staffing and funding cuts that EPA is facing.

If you have any questions, please contact attorney Martin Siegel or any member of the Barley Snyder Environment & Energy Industry Group.