On March 4, 2025, Justice Alito delivered the Supreme Court’s 5-4 decision in City and County of San Francisco, California v. EPA, holding that EPA exceeded its authority by including “end-result” provisions in pollutant discharge permits issued pursuant to the Clean Water Act. “End-result” provisions generally prohibit permit recipients from contributing to water pollution without specifying actions or objectively defined effluent limits that the permittee must meet to comply with the Clean Water Act. SCOTUS held that EPA may not establish permit requirements that simply prohibit discharges that contribute to a violation of a water quality standard. Rather, EPA must affirmatively define in the permit what steps are required or what limitation must be met by a permittee to prevent such a violation in a receiving body of water.
As background, the Clean Water Act prohibits point source discharges to a body of water subject to the Act’s jurisdiction without a National Pollutant Discharge Elimination System (NPDES) Permit. NPDES permits generally establish “effluent limitations” restricting the mass or concentration of a pollutant that can be discharged into the receiving waterbody, or specifying an operational practice standard or control technology that must be implemented by the permittee.
In San Francisco, a municipal wastewater treatment facility operated a combined sewer system, where wastewater and stormwater are combined for treatment. Heavy precipitation occasionally caused system overflows, causing the discharge of untreated wastewater. When the City renewed its NPDES permit in 2019, the EPA-issued permit included two new “end-result” requirements. One prohibited the facility from “contribut[ing] to a violation of any applicable water quality standard” for the water where the discharge is received. The second prohibited the facility from contributing to the degradation of any receiving body of water. Notably, the permit did not expressly specify how the City could meet these requirements, effectively holding the municipality strictly liable for the water quality into which it discharged pollutants.
SCOTUS held that EPA exceeded its regulatory authority in requiring such “end-result” provisions based on the larger statutory scheme of the Clean Water Act. The Court held that allowing “end-result” limitations would effectively negate the “permit shield” included in NPDES permits. The permit shield provides that a permittee is deemed in compliance with the Clean Water Act and shielded from enforcement so longs as it complies with its NPDES permit terms. “End-result” permit terms would render the permit shield moot since they lack objective criteria and specific directives by which a permit recipient would know if they were in compliance with the permit.
The Court further held that “end-result” permit terms make it virtually impossible to allocate responsibility for water quality standards in situations involving multiple dischargers to the same receiving water body. Each permittee with an “end-result” limitation could be held strictly liability for any violation of a water quality standard in the receiving water body, even if caused by another discharger.
Going forward, EPA- and state-issued pollution discharge permits will need to include specific effluent limits, best management or operational practices, and/or effluent control technologies in permits rather than imposing general outcome-based goals.
This decision will also impact other regulatory programs, including the Clean Air Act. Clean Air Act permits often contain similar “end-result” provisions, preventing permit recipients from significantly contributing to an exceedance of an ambient air standard or otherwise causing “air pollution.” See e.g., Wis. Admin. Code § NR 415.03. These general air permit directives provide no guidance or specific actions that the permittee must undertake to comply with this type of aspirational “end-result” permit term. The SCOTUS holding in San Francisco seems to squarely prohibit these types of limitation in air permits as well.
Permittees are advised to check their permits for such “end-result” language and consult legal counsel for an analysis in light of the decision and potentially applicable underlying state law.