Supreme Court Strikes Down Receiving Water Permit Limitations

The Supreme Court ruled yesterday that the U.S. Environmental Protection Agency (EPA) must establish specific numeric and narrative effluent limits in NPDES permits to achieve compliance with applicable water quality standards.[i] The Court invalidated what it described as an “end-result” narrative effluent limit prohibiting a discharge from causing a violation of water quality independent of the specific compliance conditions in a permit. In so doing, the Court made clear that an agency may not enforce permit requirements that fail to “spell out what a permittee must do or refrain from doing.”[ii]

The City and County of San Francisco (CCSF) had challenged two “end-result” conditions—permit provisions that do not set out a specific effluent limitation but instead make a permittee liable for the quality of the “receiving water” to which wastewater and/or stormwater is discharged over and above the specific conditions in permit. The Court declined to adopt CCSF’s broader argument that all “limitations” under Clean Water Act Section 1311 must qualify as effluent limitations. However, “[d]etermining what steps a permittee must take to en­sure that water quality standards are met is the EPA’s re­sponsibility, and Congress has given it the tools needed to make that determination.”[iii]

The ruling of the Court provides more certainty for NPDES permit compliance. End-result permit terms pose significant liability risks because a permittee may be in full compliance with numeric and specific narrative limitations, and yet be deemed in violation of water quality standards. Now, permit writers must continue to rely on specific, upfront conditions and not after-the-fact assessments of water quality impacts.

Factual and Procedural Background

CCSF operates two combined treat­ment facilities, including the Oceanside facility, which empties into the Pacific Ocean. The Oceanside plant was completed in 1997 and received its first National Pollution Discharge Elimination System (NPDES) permit that same year. The facility treats sanitary sewer water and stormwater from 250 miles of sewers and serves approximately 250,000 residents. During periods of heavy pre­cipitation, the combination of wastewater and stormwater may exceed the facility’s capacity, which sometimes results in untreated discharges to the Pacific Ocean. 

In 2019, following several uncontroversial renewals of the Oceanside NPDES permit, EPA and the California Regional Water Quality Control Board for the San Francisco Bay Region[iv] renewed the permit with the addition of two end result requirements: (1) that the discharge “shall not cause or contribute to a violation of any applicable water quality standard” for receiving waters; and (2) that CCSF cannot perform treatment or cause any discharge that “create[s] pollution, contamination, or nuisance as defined by California Water Code section 13050.”  CCSF challenged these requirements before the EPA Environmental Appeals Board. 

The Environmental Appeals Board rejected the City’s challenge, and the City then filed a petition for review in the United States Court of Appeals for the Ninth Circuit. A divided Ninth Circuit panel denied that petition, holding that Clean Water Act Section 1311(b)(1)(C) authorizes the EPA to impose “any” limitations that seek to ensure that applicable water quality standards are satisfied in a receiving body of water.[v] The Ninth Circuit’s decision created a circuit split—an earlier ruling by the Second Circuit held generic narrative limits in a permit regulating the discharge of ballast water from ships were too vague and lacked the guidance necessary to satisfy statutory requirements.[vi] 

Statutory Background

In 1972, Congress established a Clean Water Act permitting scheme through the creation of the NPDES program. NPDES permitting is required for any discharge of a pollutant from a point source to a water of the United States,[vii] and can apply to wastewater, stormwater, or a combination of the two. Regulated entities may apply for individual permits, or may submit a notice of intent to comply with an applicable general permit.[viii] Noncompliance with permit requirements, as well as unpermitted discharges, can be subject to government enforcement and “citizen suits.”[ix] 

The 1972 amendments distinguished between the “effluent limitations” that apply to a permittee’s discharges, and “water quality standards” established by states, territories, and tribes that set the overall goals for waters that receive not only the permittee’s discharges, but also pollutants from other sources. Because permitting was now the primary enforcement method, the amendments also provided that “compliance with a[n NPDES] permit” amounts to compliance with the Clean Water Act.[x] 

Supreme Court Opinion and Significance for Regulated Entities

Writing for the majority,[xi] Justice Alito observed that not all “limitations” under Clean Water Act Section 311 must qualify as effluent limitations. Although Sections 311(b)(1)(A) and (B) refer to “effluent limitations,” the Court noted, Section 311(b)(1)(C) refers to “any more stringent limitation.”[xii]   

However, the Court held that Section 311(b)(1)(C) does not authorize permit requirements that condition compliance on receiving water quality. As a textual matter, the Court reasoned, the Section 311(b)(1)(C) term “limitation,” is an external restriction, not an end-result requirement leaving permittees discretion in identifying and executing next steps. Similarly, the term “implement” is best understood to require concrete measures, not achievement of a given result. The Court also recognized that in its 1972 Clean Water Act amendments, Congress omitted a prior provision that allowed direct enforcement against a discharger if the quality of the receiving water failed to meet water quality standards. Finally, the Court recognized that the agency’s interpretation would render the Act’s permit shield provision meaningless.[xiii]

As noted above, the ruling of the Court will provide more certainty for NPDES permit compliance and potential enforcement. Receiving water requirements have become common in NPDES permits, and compliance is complex, given that there are typically many sources of discharges of pollutants to a receiving water. Nevertheless, they are often alleged as violations in citizen suits and government enforcement actions, even where a permittee is otherwise in full compliance with a permit. 

Please contact the authors or others in Marten Law's Water Quality practice group for more information.

[i] City and Cnty. of San Francisco v. Envtl. Protection Agency, No. 23-753 (Mar. 4, 2025). 

[ii] Id. at 2. 

[iii] Id. at 20.

[iv] EPA has authorized California to issue NPDES permits for discharges into waters within its jurisdiction, but EPA retains authority to issue permits for discharges into ocean waters more than three miles from the shore. See 33 U.S.C. § 1362(8) (defining the State's territorial seas as extending three miles from the coast). When both state and federal permits are needed for a particular treatment facility, the permitting processes may be consolidated, and permits may be issued jointly or separately. 40 C.F.R. § 124.4(c).

[v] City & Cnty. of San Francisco v. U.S. Envtl. Protection Agency, 75 F.4th 1074, 1089–90 (9th Cir. 2023). CCSF also challenged the permit’s requirement that it update its long-term control plan for combined sewer overflow control. The Ninth Circuit also rejected the City’s challenge to this provision, and the City did not include the issue in its petition for certiorari to the U.S. Supreme Court.  

[vi] NRDC v. EPA, 808 F.3d 555, 578 (2nd Cir. 2015).

[vii] 33 U.S.C. § 1311(a). 

[viii] 40 C.F.R. §§ 122.21, 122.28, 123.25.

[ix] 33 U.S.C. §§ 1319, 1365. 

[x] 33 U.S.C. § 1342(k).

[xi] Justice Barrett, joined by Justices Sotomayor, Kagan, and Jackson, dissented in part.

[xii] City and Cnty. of San Francisco v. Envtl. Protection Agency, No. 23-753, slip op. at 8-9 (Mar. 4, 2025). 

[xiii]Id. at 9-16.