The 5-to-4 decision is the latest setback for the agency and could have sweeping implications for curtailing water pollution offshore.

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.

"EPA is required to issue the limitations necessary to ensure that the water quality standards are met," Barrett wrote. "So taking a tool away from EPA may make it harder for the

The Supreme Court's conservative majority ruled for San Francisco in limiting the power of environmental regulators to prevent ocean discharges of polluted stormwater.