In addition to fees, rentals or use charges produced by the facilities constructed hereunder, the board may use any other funds legally available for such purposes to pay for costs of construction, furnishing and equipping such facilities and to pay principal and interest on bonds and for costs of operation and maintenance of such facilities provided the board may not pledge any funds of the state to payment of bonds and interest so as to create a debt of the state contrary to constitutional or statutory limitations upon the incurring of such indebtedness.