The Clean Water Act prohibits any person or entity from discharging any pollutant from a point source to a water of the United States unless the discharge is authorized, for example, by a National Pollutant Discharge Elimination System (NPDES) permit. The NPDES regulations identify requirements that must be included in application forms used for different classes of discharges. NPDES permit applicants must only 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 NPDES application regulations has not been updated since 1987 and currently does not include PFAS. This proposed rulemaking seeks to update requirements for several of the existing NPDES permit applications to address monitoring and reporting of PFAS.