Supreme Court Limits EPA's Power Over NPDES Water Permits

In a much-anticipated decision, the U.S. Supreme Court significantly narrowed the EPA's authority under the Clean Water Act (CWA) to impose so-called "end-result" requirements in NPDES permits.¹ These "end-result" requirements "do not spell out what a permittee must do or refrain from doing" but instead hold dischargers accountable for the condition of receiving waters, not just the nature of their discharges.

The case involved the City and County of San Francisco, which challenged NPDES permit conditions prohibiting discharges that "cause or contribute to" violations of water quality standards. A divided Ninth Circuit panel upheld the language, but the Supreme Court disagreed. In a 5-4 opinion reversing the Ninth Circuit, the Court sided with the City and County of San Francisco. The Court held that while the EPA can impose effluent limits and other specific requirements, it cannot condition permit compliance on whether receiving waters ultimately meet state