The Clean Water Act prohibits discharging pollutants from a point source into a water of the United States unless the discharge is authorized by a national pollutant discharge elimination system (NPDES) permit. The NPDES regulations identify requirements that must be included in application forms that are used for different classes of discharges. NPDES permit applicants are only required to report to the permitting authority pollutants in their discharge that are listed in the application regulations at 40 CFR 122.21. The list of pollutants in the application regulations has not been updated since 1987 and currently does not include per- and polyfluoroalkyl substances (PFAS). Based on limited compliance data, EPA has determined that currently less than 1% of facilities covered by an NPDES permit contain any PFAS related requirements such as monitoring, best management practices and/or effluent limits, resulting in the need to require permit applicants with PFAS in their discharges to notify the permitting authority prior to permit issuance to protect public health and the environment. This proposed rulemaking seeks to update requirements for several of the existing NPDES permit applications to address monitoring and/or reporting of PFAS.