A State which has failed to obtain the approval of a State program prior to implementation of a Federal program may submit a State program at any time after such implementation. Upon the submission of such a program, the Secretary shall follow the procedures set forth in section
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(b) of this title and shall approve or disapprove the State program within six months after its submittal. Approval of a State program shall be based on the determination that the State has the capability of carrying out the provisions of this chapter and meeting its purposes through the criteria set forth in section
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(a)(1) through (6) of this title. Until a State program is approved as provided under this section, the Federal program shall remain in effect and all actions taken by the Secretary pursuant to such Federal program, including the terms and conditions of any permit issued thereunder shall remain in effect.