Any city which now has or may hereafter contain more than one hundred thousand inhabitants shall have power to contract with drainage districts or with other public corporations in this or any adjoining state for cooperation or joint action in building sanitary and storm sewers in watersheds extending into the territorial limits of all the districts, or corporations so cooperating, and in constructing levees along the banks of, or shortening, diverting or otherwise improving any natural watercourse to prevent its overflow, where the same overflow is likely to cause injury or damage to lands situated within the territorial limits of all the districts or corporations so cooperating; also to receive aid from, contract and cooperate with the United States, and with public and with private corporations and with individuals owning or exercising jurisdiction over lands wheresoever situated which are subject to injury by such overflow, or which may require the building of such sewers.