The Water and Power Resources Board¹ is hereby authorized to consult, cooperate, negotiate and, with the approval of the Attorney General, enter into contracts and other agreements with the Federal government, any political subdivisions, municipality, authority, corporation, association, person or persons for cooperation and assistance in planning, constructing, financing, maintaining and operating any works or facilities needed to carry out the intent of this act: Provided, That all work of any character whatsoever performed under the authority of this act, except as undertaken by its own forces or other agencies of the Commonwealth, or of the Federal government shall be performed under written contract, let by the Water and Power Resources Board to the lowest responsible bidder, after due advertisement, as provided by law, and in accordance with plans and specifications prepared by the board.