On September 29, 2023, Region III ECAD issued an Administrative Order on Consent (AOC) to the City of Williamsport, PA, (the City) requiring specific work to achieve compliance with a NPDES Individual Permit for Discharges from Small Municipal Separate Storm Sewer Systems Permit (the MS4 Permit), issued by Pennsylvania Department of Environmental Protection (PADEP). The MS4 Permit regulates discharges from the permitted MS4 area to the rivers and tributaries within the Chesapeake Bay and Susquehanna River watersheds. The agreed upon AOC is the final stage towards addressing numerous areas of noncompliance with the MS4 Permit. EPA?s July 2022 Notice of Potential Violation and Opportunity to Confer (NOPVOC) identified a broad range of areas of noncompliance, which initially came to EPA?s attention during a remote/off-site NPDES permit compliance audit and separate on-site compliance inspection of the City?s MS4 Program. During post-NOPVOC negotiations, the City and EPA coordinated on necessary actions to further define and address areas of noncompliance. For example, during calendar years 2022-2023, the City identified more than 400 MS4 outfalls, which had been previously unidentified and had not been inspected in accordance with the MS4 Permit. The AOC reflects agreement between the City and EPA as to significant injunctive relief necessary to address numerous areas of MS4 Permit noncompliance. For summary purposes, the AOC requires the City to: a) revise and update Respo