As we look forward to 2026, we wanted to share with you a series of blogs to recap of some of the worst U.S. Supreme Court decisions that will shape our ability to protect our environment for decades to come. (Blog 4/4) 

Supreme Court Limits EPA’s Use of “End-Result” Provisions in NPDES Permits 

In City & Cty. of S.F. v. EPA, 145 S. Ct. 704 (2025), the Supreme Court struck down certain narrative (as opposed to numeric) standards that the Environmental Protection Agency (EPA) had included in San Francisco’s National Pollutant Discharge Elimination System (NPDES) permit under the Clean Water Act (CWA). 

NPDES permits are required for discharges of pollution from a point source into waters of the United States. In this case, the San Francisco’s wastewater treatment plant had a permit issued by EPA. 

Typically, an NPDES permit specifies discharge limits or treatment requirements, whether they be numeric (e.g., pH) or narrative (e.g., “no visible sheen”) limits. If the permit holder complies with those requirements, the “permit shield” provision in the CWA deems them in compliance with the Act. This approach provides regulatory certainty: following the permit’s explicit terms should protect the permittee from additional liability. 

However, in 2019 the EPA added two provisions to San Francisco’s wastewater treatment permit that imposed liability if the water receiving the discharge failed to meet certain quality standards, regardless of whether the City had met all other permit conditions. One provision prohibited any discharge that “contributes to” a violation of applicable water quality standards. The other prohibited any discharge that “creates pollution, contamination, or nuisance” under California law. These types of limits are quite comment in NPDES permits, and can allow the permittee the flexibility on how to create the most cost-effective way to comply with these requirements.  

The Court, in overturning the permit, created a new term “end-result provision” and held that the CWA authorizes the EPA to impose limitations that are within the permittee’s control, such as limits on the facility’s own discharges, not broad results that depend on downstream conditions influenced by many other factors (e.g., the end result). By requiring San Francisco to ensure downstream water quality regardless of other pollution sources, the Supreme Court held that EPA exceeded its statutory authority. This decision unnecessarily removed a tool from the EPA’s regulatory belt, one that will likely make it harder to keep our waters clean.  

This case illustrates how Loper Bright Enterprises v. Raimondo continues to shape judicial review of agency actions. In Loper Bright, the Court ended the Chevron doctrine, meaning courts no longer defer to an agency’s reasonable interpretation of ambiguous statutes. Instead, judges independently interpret the law’s meaning. Here, the Court analyzed the Clean Water Act and concluded that Congress only empowered the EPA to regulate a permittee’s own discharges not to hold it responsible for the condition of the water body as a whole. Under Chevron, the Court would have analyzed whether the EPA’s interpretation of the Clean Water Act was reasonable, and if it was, they would give their interpretation deference, most likely siding with them over these provisions. Now under Loper Bright, the Court is given the final say in how the EPA, and other agencies, are allowed to fulfill their statutory charges. In this case, determining that the EPA’s long-used “end-result provisions” are not authorized. 

PennFuture’s attorneys are working hard to protect our environment and the rule of law. Support our efforts by donating to our Legal Environmental Advocacy Fund (LEAF) today!