Whenever any of the facilities, works, or utilities of the district, or part thereof, is not used or employed to its fullest capacity for the benefit or requirements of the district or its inhabitants, the district may enter into an agreement with public agencies or any person, firm, or corporation, upon such terms and conditions as are satisfactory to the board, for renting, leasing, or otherwise using the available portion or parts of the facilities, works, or utilities, and in connection with any such agreement, renting, or leasing the district may undertake or perform any services incidental thereto.