Under Clean Water Act section 401, a federal agency may not issue a license or permit to conduct any activity that may result in a discharge into a water of the United States unless a section 401 water quality certification is issued, or certification is waived by a state or authorized Tribe. EPA last promulgated regulations on CWA section 401 in 2023, including regulatory text addressing the scope of certification. This action will clarify the scope of certification regarding implementation challenges and regulatory uncertainty associated with the scope of certification in the 2023 Rule. This action will increase transparency, efficiency, and predictability for co-regulators and the regulated community.