On March 4, 2025, the U.S. Supreme Court issued its decision in City and County of San Francisco, California v. Environmental Protection Agency, ruling that two “end-result” requirements in the National Pollutant Discharge Elimination System (NPDES) permit issued by the Environmental Protection Agency (EPA) in 2019 exceeded the agency’s authority under the Clean Water Act (CWA). In this case, the City and County of San Francisco (San Francisco) challenged the EPA’s renewal of an NPDES permit that imposed two “end-result” restrictions: (1) prohibiting discharges that “contribute to a violation of any applicable water quality standard” for receiving waters, and (2) barring any treatment or discharge that “create[s] pollution, contamination, or nuisance as defined by California Water Code section 13050.”[2]

The core legal issue centered on 33 U.S.C. § 1311(b)(1)(C), which allows the EPA to impose “any more stringent limitation, including those necessary to meet water quality standards, treatment standards, or schedules of compliance” other than those “effluent limitations” which might restrict quantities of certain specific pollutants in the discharge.[3] San Francisco contended that the EPA exceeded its authority by incorporating in its permit general “end-result” requirements instead of concrete effluent limitations, which effectively exposes the city to strict liability whenever the quality of the receiving waters does not meet the applicable water quality standards.[4] The EPA, in turn, argued that the statutory language granting it broad authority to impose “any more stringent limitation” permitted it to include these narrative provisions in its permits.[5] In a 5-4 decision, the Court refused to defer to the EPA’s interpretation, asserting that its reading of the CWA conflicted with the Court’s textual interpretation.[6] The majority held that the CWA does not authorize the EPA to impose broad “end-result” requirements in NPDES permits.[7]

This case marked one of the first major Supreme Court decisions following the overturning of the Chevron doctrine in June 2024, reversing the decades-long judicial deference to agency interpretation of statutes.[8]  In its analysis, the Court mostly relied on its textualist reading of the statute and reasoned that the word “limitation” only means “restriction or restraint imposed from without” and should not include certain end goals where the permittee must figure out the restrictions that it must impose to itself to achieve the end goal.[9] This type of restriction, the Court reasoned, comes from within, rather than from without, and thus does not fall under “limitation” within the meaning of the CWA.[10] Another touchstone in the Court’s reasoning is the “permit shield” provision found in 33 U.S.C. § 1342(k), which provides that a permittee should be deemed in compliance with the CWA if it follows the terms of a permit.[11] The Court reasoned that this safe harbor “would be eviscerated if the EPA could impose a permit provision making the permittee responsible for any drop in water quality below the accepted standard.”[12]

The ruling has sparked mixed reactions. Stakeholders on the side of permittees argue that the decision provides greater clarity and predictability for permit holders, ensuring they have concrete standards to follow without fear of uncertain liability.[13] Conversely, environmental advocates view the decision as another step in the Court’s broader effort to curtail the EPA’s regulatory authority.[14] The Sierra Club criticized the ruling, stating that it “ignores the basic reality of how water bodies and water pollution work” and could hinder the EPA’s ability to enforce the CWA effectively.[15] Justice Barrett, in her dissent, also warned that the decision could lead to delays or even denials in NPDES permit application process, as the EPA may now require more extensive resources and information to craft individualized and prescriptive permit conditions.[16]

The long-term impact of this ruling remains uncertain, but it exemplifies the evolving landscape of environmental and administrative law. The decision underscores the Supreme Court’s shift away from deferring to agency expertise and reflects ongoing progress to constrain the EPA’s regulatory power and flexibility under the CWA. As regulatory agencies and permit holders adapt to this ruling, its implications for water pollution control and environmental governance will continue to unfold.

[1] City & Cnty. of San Francisco, California v. Env’t Prot. Agency, No. 23-753, slip op. at 3 (U.S. Mar. 4, 2025).

[2] Id. at 5.

[3] Id. at 3 (citing 33 U.S.C. § 1362(11)).

[4] Id. at 7.

[5] Id. at 8.

[6] Id. at 12.

[7] Id. at 3.

[8] See Loper Bright Enters. v. Raimondo, 603 U.S. 369, 412 (2024) (overruling Chevron, U.S.A., Inc. v. Nat. Res. Def. Council, Inc., 467 U.S. 837 (1984)); See also Berit DeGrandpre, City and County of San Francisco v. Environmental Protection Agency Brings Questions of Agency Deference Back in Front of the Supreme Court, Geo. Env’t  L. Rev. (Oct. 3, 2024), https://www.law.georgetown.edu/environmental-law-review/blog/city-and-county-of-san-francisco-v-environmental-protection-agency-brings-questions-of-agency-deference-back-in-front-of-the-supreme-court/.

[9] San Francisco, slip op. at 7.

[10] Id. at 10.

[11] Id. at 9 (citing 33 U.S.C. § 1342(k)).

[12] Id. at 10.

[13] See, e.g., Supreme Court Issues Decision in San Francisco’s Favor in Water Quality Permitting Case, S.F. Water Power Sewer (Mar. 4, 2025), https://www.sfpuc.gov/about-us/news/supreme-court-issues-decision-san-franciscos-favor-water-quality-permitting-case.

[14] See, e.g., Emily Driscoll, U.S. Supreme Court further erodes Clean Water Act protections, S. Env’t L. Center (Mar. 4, 2025), https://www.selc.org/press-release/u-s-supreme-court-further-erodes-clean-water-act-protections/.

[15] Sander Kushen, Supreme Court Rules Against EPA and Clean Water Act Protections, Sierra Club (Mar. 4, 2025), https://www.sierraclub.org/press-releases/2025/03/supreme-court-rules-against-epa-and-clean-water-act-protections.

[16] San Francisco, slip op. at 18.