For the purpose of carrying out any of the provisions of sections 23-320.01 to 23-320.06, the county board is hereby authorized to enter into agreements with (1) the United States of America or any department or agency thereof, (2) any city, (3) any drainage district, (4) any other county, (5) any natural resources district, (6) any irrigation district, (7) any reclamation district, (8) any body politic, (9) any person, (10) any firm, or (11) any individual, whenever it shall be necessary as a condition to the construction of flood control works or other similar projects hereunder, and for the maintenance, repair, or operation thereof. To aid and assist in carrying out a coordinated soil and water resource program or program of flood control for any county, the county board may also employ the services of any nonprofit corporation or organization that has as one of its principal objectives or purposes the promotion and development of soil and water resource projects and flood control and to receive gifts and contributions from public and private sources to be expended in providing funds for construction costs and expenses in excess of funds to be provided by the federal government and the tax levy.