The US supreme court has weakened rules on the discharge of raw sewage into water supplies in a 5-4 ruling that undermines the 1972 Clean Water Act.

The CWA is the principle law governing pollution control and water quality of the nation’s waterways.

The Republican super majority court ruled on Tuesday that the Environmental Protection Agency (EPA) cannot employ generic, water body-focused pollution discharge limits to Clean Water Act permit holders, and must provide specific limitations to pollution permittees.

The ruling is a win for San Francisco, which challenged nonspecific, or “narrative,” wastewater permits that the EPA issues to protect the quality of surface water sources like rivers and streams relied upon for drinking water.

In a 5-4 ruling written by Justice Samuel Alito, the court blocked the EPA from issuing permits that make a permittee responsible for surface water quality, or “end result” permits – a new term coined by the court.

“The agency has adequate tools to obtain needed information from permittees without resorting to end-result requirements,” […]