The Secretary of the Army is authorized to receive from States and political subdivisions thereof and other non-Federal interests, such funds as may be contributed by them for work, which includes planning and design, to be expended in connection with funds appropriated by the United States for any authorized water resources development study or project, including a project for navigation on the inland waterways, whenever such work and expenditure may be considered by the Secretary of the Army, on recommendation of the Chief of Engineers, as advantageous in the public interest, and the plans for any reservoir project may, in the discretion of the Secretary of the Army, on recommendation of the Chief of Engineers, be modified to provide additional storage capacity for domestic water supply or other conservation storage, on condition that the cost of such increased storage capacity is contributed by local agencies and that the local agencies agree to utilize such additional storage capacity in a manner consistent with Federal uses and purposes: Provided, That the Secretary is authorized to receive and expend funds from a State or a political subdivision thereof, and other non-Federal interests or private entities, to operate a hurricane barrier project to support recreational activities at or in the vicinity of the project, at no cost to the Federal Government, if the Secretary determines that operation for such purpose is not inconsistent with the operation and maintenance of the project for the authorized purposes of the project: Provided further, That the Secretary is authorized to receive and expend funds from an owner of a non-Federal reservoir to formulate, review, or revise operational documents for any non-Federal reservoir for which the Secretary is authorized to prescribe regulations for the use of storage allocated for flood control or navigation pursuant to section 709 of this title: Provided further, That when contributions made by States and political subdivisions thereof and other non-Federal interests, are in excess of the actual cost of the work contemplated and properly chargeable to such contributions, such excess contributions may, with the approval of the Secretary of the Army, be returned to the proper representatives of the contributing interests: Provided further, That the term “States” means the several States, the District of Columbia, the commonwealths, territories, and possessions of the United States, and Federally recognized Indian tribes: Provided further, That the term “non-Federal interest” has the meaning given that term in section 1962d–5b of title 42.