In the prosecution of projects for rivers and harbors and other waterways for the benefit of navigation, the control of destructive flood waters, hurricane protection, beach erosion control, and for other purposes, authorized to be prosecuted under the direction of the Secretary of the Army under the supervision of the Chief of Engineers in accordance with plans adopted and authorized by the Congress, it is hereby declared to be the policy of the Congress, that whenever such projects are located wholly or partially within an area which is eligible for financial assistance under the Public Works and Economic Development Act of 1965 [
42 U.S.C.
3121 et seq.], the Secretary of Commerce is authorized to purchase evidences of indebtedness and to make loans for a period not exceeding fifty years to enable responsible local interests to meet the requirements of local cooperation pertaining to contributions toward the cost of construction of such projects within such areas.