The justices ruled that the agency cannot impose generic prohibitions against violating water quality standards.

By a 5-4 vote, the court's conservative majority ruled that the Environmental Protection Agency overstepped its authority under the Clean Water Act with water pollution permits that contain vague requirements for maintaining water quality. The decision is the latest in which conservative justices have reined in pollution control efforts.

On Tuesday, the Supreme Court substantially weakened federal limitations on raw sewage discharge into nearby bodies of water. Its 5–4 decision will, in practice, free cities to dump substantially more sewage into rivers,