United States Supreme Court Declares The EPA Cannot Impose “End-Result” Requirements in NPDES Permits

On March 4, 2025, the United States Supreme Court (SCOTUS) in a 5-4 decision issued an opinion in City and County of San Francisco, California v. Environmental Protection Agency (Opinion) 604 U.S. ___, 145 S. CT. 704 (2025) 23-753_f2bh.pdf)) in favor of San Francisco. The Opinion evaluates the authority of the Environmental Protection Agency (EPA) to impose “end-result” requirements in National Pollutant Discharge Elimination System (NPDES) permits under the Clean Water Act (CWA). SCOTUS struck down two provisions in San Francisco’s NPDES permit regarding discharges of wastewater and stormwater into the ocean.

Background

The CWA was enacted in 1972 by Congress. It aims to restore and maintain the integrity of the nation’s waters by preventing water pollution, preserving water quality, and protecting aquatic ecosystems. The CWA mandates clear, proactive permits to prevent pollution at its source. This approach ensures that dischargers have specific, manageable limits, shifting away from post-pollution enforcement. The CWA established a system of permits for wastewater and stormwater discharges. These permits set specific limits (effluent limitations) on the levels of pollutants that can be discharged into water bodies.

The Environmental Protection Agency (EPA) oversees the implementation of the CWA, while state agencies play a role in issuing permits and monitoring compliance. States are required to establish water quality standards for bodies of water within their jurisdictions. These standards set the acceptable levels of pollutants for different uses, such as recreation, drinking water, or supporting aquatic life.

End-result requirements, as characterized by SCOTUS, in NPDES permits are provisions that do not specify the exact actions a permittee must take or refrain from taking. ​Instead, they make the permittee responsible for ensuring that the quality of the water in the body of water into which they discharge pollutants meets applicable water quality standards. Essentially, these requirements focus on the final outcome – the quality of the receiving water – rather than detailing specific steps or measures the permittee must follow to achieve that outcome. ​

The Supreme Court’s Analysis

The city has a combined wastewater and stormwater system that treats almost all water before discharging it into the Pacific Ocean, setting a high environmental standard compared to other municipalities. The permit prohibited the facility from making any discharge that “contribute[s] to a violation of any applicable water quality standard” for receiving waters. The permit stipulated that the City cannot perform any treatment or make any discharge that “create[s] pollution, contamination, or nuisance as defined by California Water Code section 13050.”

The Court struck down “end-result” requirements like receiving water limits, emphasizing that discharge permit conditions must regulate the quality of water being discharged, not the quality of the receiving waters. The majority held that “limitations” in the CWA refer to specific, concrete actions that permittees must follow, rather than broad end-result requirements.

The Court highlighted that the CWA replaced pre-1972 rules where dischargers were liable for receiving water quality. The Court also stressed the importance of the CWA’s “permit shield,” which protects entities complying with their permits from penalties. The majority opinion emphasized that the EPA exceeded its authority by including end-result provisions, favoring concrete, specific instructions for compliance. It highlighted Congress’s intent to move away from vague requirements under the Water Pollution Control Act.

Justice Barrett’s dissent argued that end-result provisions provide flexibility and are beneficial when detailed information is unavailable. The dissent suggested they are consistent with the CWA’s goals. Justice Barrett highlighted that the CWA's focus is on proactive measures to prevent pollution, and receiving water limitations align with this goal as supplementary tools. The dissent saw value in end-result provisions, particularly when precise data is unavailable, enabling timely issuance of permits without unnecessary delays. It argued that compliant permittees would still be protected under the “permit shield” even with end-result provisions, and fairness concerns could be addressed through challenges to specific terms.

While this decision creates clarity about “end-result” requirements, only time will tell whether those existing permit holders with similar provisions might initiate the administrative process with the EPA, or go straight to court, to have those provisions modified in accordance with San Francisco v. EPA.