Supreme Court Strikes Down ​"End-Result" Requirements In NPDES Permits

On March 4, 2025, the U.S. Supreme Court issued a ruling that prohibits the U.S. Environmental Protection Agency ("EPA" or "the Agency") from setting qualitative limits based on the condition of the "receiving waters" that the permit authorizes discharge into, rather than specific limits on the permittee's discharge itself. The Court did uphold the Agency's ability to issue non-numerical (i.e., "narrative") permit limits, but ruled that these limits must explicitly "spell out what a permittee must do or refrain from doing."¹ This Client Advisory will first discuss the background of the case, explain the holding, and then outline key takeaways that National Pollutant Discharge Elimination System ("NPDES") permit holders should consider moving forward.