On December 1, 2022, EPA issued an Administrator’s Determination that revised water quality standards (WQS) in certain zones of the Delaware River are necessary to meet the requirements of the CWA. Specifically, EPA determined that a propagation designated use and protective dissolved oxygen criteria are required to protect sensitive aquatic life – including two federally listed species under the Endangered Species Act – in zones 3, 4, and upper-5 of the Delaware River. EPA is now fulfilling its statutory obligation to promulgate the necessary WQS.