at the cost of the non-Federal interest, carry out a feasibility study to modify the project for deepening in accordance with section 203 of the Water Resources Development Act of 1986 ( 33 U.S.C. 2231 ). (2) Requirement A modification recommended by a feasibility study under paragraph (1) shall be approved by the Secretary and authorized by Congress before construction. (b) Prior written agreements (1) Prior written agreements for section 203 To the maximum extent practicable, the Secretary shall use the previous agreement between the Secretary and the non-Federal interest for the feasibility study carried about under section 203 of the Water Resources Development Act of 1986 ( 33 U.S.C. 2231 ) that resulted in the project described in subsection (a)(1) in order to expedite the revised agreement between the Secretary and the non-Federal interest for the feasibility study described in that subsection. (2) Prior written agreements for technical assistance On the request of the non-Federal interest described in subsection (a)(1), the Secretary shall use the previous agreement for technical assistance under section 203 of the Water Resources Development Act of 1986 ( 33 U.S.C. 2231 ) between the Secretary and the non-Federal interest in order to provide technical assistance to the non-Federal interest for the feasibility study under subsection (a)(1). (c) Submission to Congress The Secretary shall— (1) review the feasibility study under subsection (a)(1)