The Clarifying Federal General Permits Act amends the Federal Water Pollution Control Act to enhance the administration of general permits under the National Pollutant Discharge Elimination System (NPDES). It explicitly authorizes the Administrator to issue general permits on a State, regional, nationwide, or delineated area basis for categories of activities with similar types of discharges from similar sources. A key provision addresses permit expiration, requiring the Administrator to publish a notice in the Federal Register at least two years in advance if a new general permit for similar discharges will not be issued. If such a notice is not provided, the terms and conditions of the expired general permit will continue to apply to both existing and new discharges that would have been covered. This continuation lasts until a new permit is issued or two years after a non-renewal decision is officially published, providing regulatory certainty during transitions.