In order to carry out the provisions of sections 277 to 277d of this title, the President, or any Federal agency he may designate is authorized, (a) in his discretion, to enter into agreements with any one or more of said political subdivisions, in connection with the construction of any project or works provided for in paragraph (2) of section 277a and section 277b of this title, under the terms of which agreements there shall be furnished to the United States, gratuitously, except for the examination and approval of titles, the lands or easements in lands necessary for the construction, operation, and maintenance in whole or in part of any such project or works, or for the assumption by one or more of any such political subdivisions making such agreement, of the operation and maintenance of such project or works in whole or in part upon the completion thereof: Provided, however, That when an agreement is reached that necessary lands or easements shall be provided by any such political subdivision and for the future operation and maintenance by it of a project or works or a part thereof, in the discretion of the President the title to such lands and easements for such projects or works need not be required to be conveyed to the United States but may be required only to be vested in and remain in such political subdivision; (b) to acquire by purchase, exercise of the power of eminent domain, or by donation, any real or personal property which may be necessary; (c) 1