Patrick Schlesinger (he/him), Environmental Law Review Staffer, Fordham Law 2026

The Court’s Decision

On March 4th, 2025, the Supreme Court issued its opinion in City and County of San Francisco v. Environmental Protection Agency. The decision rested on the resolution of an ambiguous statutory provision in the Clean Water Act (the Act). Consistent with its authority in a post-Loper Bright landscape, the 5-4 majority applied canons of statutory interpretation and legislative history to determine the meaning of the Act, and did not defer to agency interpretation. While the Court ultimately rejected the arguments of both San Francisco and the EPA, the Court held that the EPA had exceeded its statutory authority in regulating what it described as “end result requirements.” 

End result requirements refer to limitations on the levels of pollutants in a body of water in which effluent is dumped. This is contrasted with restrictions on the content of the effluent itself. The majority opinion held that end result requirements are outside the scope of the EPA’s authority and inconsistent with the meaning of the act. The justices reasoned that creating end result requirements was unfair in that a single body of water (such as the San Francisco Bay) may have many different sources of pollution, yet a single polluter (such as the City and County of San Francisco) could be held liable for all the pollution. Moreover, the majority held that the Clean Water Act only authorizes the EPA to regulate the effluent itself, and not to restrict pollutant levels in the body of water in which the effluent is discharged. 

Justice Barrett (joined by justices Kagan, Jackson, and Sotomayor) excoriated the majority’s reasoning in a partial dissent. The minority found that the shift in language from end result requirements (of the earlier Water Pollution Control Act) to effluent limitations (of the Clean Water Act) was not the result of congressional intent to disallow end result requirements. Rather, the shift reflected practical considerations that effluent limitations would be easier to enforce. Further, the minority found that when Congress authorized the EPA to promulgate “any more stringent limitation… required to implement any applicable water quality standard,” Congress imbued the Agency with the authority to create end-result requirements. 

Current System and Takeaways

The Clean Water Act is enforced through the National Pollutant Discharge Elimination System (NDPDES). The EPA issues permits to cities and others who discharge effluent, with limitations on the quality of “quantities, rates, and concentrations of chemical, physical, biological, and other constituents.” Although discharge of effluent is presumptively unlawful, if a permit-holder complies with the terms of its permit, then the effluent is in compliance with the Act. 

This system of regulating effluent in compliance with the NDPDES will remain in place. However, the San Francisco decision means that the EPA must be explicit and require specific actions that each permit holder must take. Takeaways include:

• Shifting Responsibility to the EPA: The Court’s decision places the onus on the EPA to develop explicit compliance measures for NPDES permits. This change limits the ability of the agency to rely on general end-result requirements.
  
• Changes in NPDES Permit Processing: As the EPA will now need to specify actions permittees must take to comply with water quality standards, the process of issuing NPDES permits may become more time-consuming and complex. Commentators note that especially given the current administration’s elimination of federal employees, it is unclear whether the agency has the capacity to develop individualized restrictions for permit-holders in a timely fashion.
  
• State-Level Impact: This decision only impacts the federal NPDES program. States with their own discharge-permitting authority under state laws–such as the Porter-Cologne Act in California–may continue to impose “end-result” provisions for state-level permits. 

This decision will reshape the administration of the Clean Water Act. By ruling that end result requirements cannot be included in NPDES permits, the Court has shifted the regulatory burden back onto the EPA. While this decision offers greater clarity for permittees, it may also complicate and lengthen the permit-issuance process. Long-term implications on the permitting process–and water quality–remain to be seen.