§ 171.309 Modification and withdrawal of approval of certification plans.
(a) Modifications to approved certification plans. A State, Tribe, or Federal agency may make modifications to its approved certification plan, provided that all of the following conditions are met:
(1) Determination of plan compliance. Before modifying an approved certification plan, the State, Tribe, or Federal agency must determine that the proposed modifications will not impair the certification plan's compliance with the requirements of this part or any other Federal laws or regulations.
(2) Requirement for Agency notification. The State, Tribe, or Federal agency must notify the Agency of any plan modifications within 90 days after the final State, Tribal, or Federal agency plan modifications become effective or when it submits its required annual report to the Agency, whichever occurs first.