In City and County of San Francisco v. Environmental Protection Agency, the Supreme Court addressed the scope of the EPA's authority under the Clean Water Act (CWA). The case arose when the EPA issued a National Pollutant Discharge Elimination System (NPDES) permit to San Francisco's wastewater treatment facilities, including provisions that prohibited discharges contributing to violations of water quality standards and creating pollution or nuisance as defined by California law. San Francisco challenged these "end-result" requirements, arguing they exceeded the EPA's statutory authority.

The Ninth Circuit upheld the EPA's permit conditions, interpreting Section 1311(b)(1)(C) of the CWA to authorize any limitations necessary to meet water quality standards, not limited to specific effluent limitations.

The Supreme Court reversed this decision, holding that Section 1311(b)(1)(C) does not authorize the EPA to include "end-result" provisions in NPDES permits. The Court emphasized that it is the EPA's responsibility to determine specific steps a permittee must take to ensure compliance with water quality standards, rather than imposing broad, outcome-based requirements.

Justice Samuel Alito delivered the opinion of the Court, in which Chief Justice John Roberts and Justices Clarence Thomas and Brett Kavanaugh joined. Justice Neil Gorsuch joined as to all but Part II. Justices Sonia Sotomayor, Elena Kagan, Amy Coney Barrett, and Ketanji Brown Jackson joined as to Part II. Justice Barrett filed an opinion dissenting in part, joined by Justices Sotomayor, Kagan, and Jackson.

Read by RJ Dieken.