This action finalizes the residual risk and technology review (RTR) conducted for the Publicly Owned Treatment Works (POTW) source category regulated under national emission standards for hazardous air pollutants (NESHAP). In addition, we are taking final action addressing revised names and definitions of the subcategories, revisions to the applicability criteria, revised regulatory provisions pertaining to emissions during periods of startup, shutdown, and malfunction (SSM), initial notification requirements for existing Group 1 and Group 2 POTW, revisions to the requirements for new Group 1 POTW, requirements for electronic reporting, and other miscellaneous edits and technical corrections. While we do not anticipate any emission reductions as a result of these revisions, the changes should provide clarity for sources determining applicability and ensuring compliance.