during such additional period thereafter as, in the case of any river the report for which is submitted to the President and the Congress, is necessary for congressional consideration thereof or, in the case of any river recommended to the Secretary of the Interior for inclusion in the national wild and scenic rivers system under
section 1273(a)(ii) of this title, is necessary for the Secretary’s consideration thereof, which additional period, however, shall not exceed three years in the first case and one year in the second.