City and County of San Francisco, California, Petitioner v. Environmental Protection Agency

The Supreme Court ruled that the Clean Water Act does not authorize the EPA to include generic "end-result" provisions in wastewater discharge permits that hold permittees liable for water quality standards without specifying the concrete limits they must meet. The decision reversed a lower court ruling, emphasizing that the EPA must define specific compliance measures rather than forcing permit holders to determine how to achieve broad water quality goals.