U.S. Supreme Court Strikes Down Nonquantifiable Water Quality Permit Requirements

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