By Leonard H. Dougal and Alicia R. French

On March 4, 2025, the United States Supreme Court issued a decision in City and County of San Francisco v. Environmental Protection Agency^[i], which restricted the scope of the Environmental Protection Agency’s (“EPA”) permitting authority under the Clean Water Act (“CWA”).

The central issue involved a critical component of the CWA — National Pollutant Discharge Elimination System (“NPDES”) permitting, which makes it un­lawful to discharge pollutants into covered bodies of water unless authorized by permit. The City and County of San Francisco challenged the EPA’s authority to impose “end-result” requirements in its NPDES permit. The challenged permit provisions prohibited the City from: (1) making any discharge that contributes to a violation of any applicable water quality standard for receiving waters; and (2) performing any treatment or making any dis­charge that creates pollution, contamination, or nuisance as defined by California law.

The Supreme Court held that the CWA does not authorize the EPA to impose “end-result” NPDES permit re­quirements that condition a permittee’s compliance on whether receiving waters meet applicable water quality standards, and thus struck down the two provisions challenged by the City. In the ruling, the Court emphasized that the CWA requires the EPA to impose specific effluent limitations and actions that permittees must take, rather than holding them responsible for achieving a particular end result in receiving waters.

In reaching its conclusion, the Court relied in part on the CWA’s “permit shield” pro­vision. Under that provision, an entity that adheres to the terms of its permit is deemed to be compliant with the CWA. See, 33 USC 1342(k)^[ii]. The Court reasoned that the benefit of this provision would be eviscerated if the EPA could impose a permit provision making the permittee responsible for any degradation of water quality below the accepted standard, even where the permittee complied with all other permit terms. In Texas, much of the NPDES permitting program is delegated to the Texas Commission on Environmental Quality, which acts as the primary permitting agency, rather than the EPA.

Key Takeaways

1.  Clarity and Predictability

The ruling benefits permit holders by providing greater clarity and predictability regarding their wastewater permit obligations under the CWA. By requiring the permitting agency to specify requirements that permit holders must follow and prohibiting the agency from relying on more vague “end-result” provisions, permittees can better understand and comply with their legal responsibilities without the fear of unexpected penalties based on water quality outcomes that may be beyond their control.

2.  Protection from Liability

The decision reinforces the CWA’s “permit shield” provision, ensuring that permit holders who adhere to the specific terms of their permits are deemed to be in compliance with the CWA. This protection is crucial for permit holders, as it allows them to operate with the assurance that compliance with their permit terms will shield them from civil and criminal penalties under the CWA.

3.  Allocation of Responsibility

The ruling helps ensure permit holders will not be unfairly penalized for water quality issues that may be caused by other sources of pollution, especially given that there may be dozens or hundreds of permitted and unpermitted discharges into a given waterbody.

4.  Existing Permits and Next Steps

Entities holding NPDES permits should review their permits in light of this decision and consider whether they contain “end-result” type provisions and are thus objectionable. For further information on how this new decision may impact your operations, permits or planned projects, or for assistance in navigating the complexities of NPDES permitting, please contact a member of our Environmental and Regulatory practice.

[i] City & Cnty. of San Francisco, California v. Env’t Prot. Agency, 604 U.S. ____, 2025 WL 676441

[ii] 33 USC 1342(k)

The opinions expressed are those of the authors and do not necessarily reflect the views of the firm, its clients, or any of its or their respective affiliates. This article is for informational purposes only and does not constitute legal advice. For questions related to the City and County of San Francisco v. Environmental Protection Agency decision, please contact a member of the Environment & Natural Resources practice.