The justices heard arguments on Wednesday in a long-simmering dispute between San Francisco and the E.P.A. over regulation of water pollution.

The justices have spent the last few years invalidating environmental protections and handcuffing federal regulators. There’s more in store this term.

The Supreme Court appeared ready in oral arguments Wednesday to restrict the EPA’s ability to set broad water quality standards for sewage and other systems as part of a challenge from San Francisco to the agency’s powers under the Clean Water Act.