The State covenants and agrees with the holders of any of the revenue bonds or other obligations issued by the Department under this chapter or any prior law for which there may be pledged the tolls, rents, rates or other revenues, or any part thereof, of the Bridge, that so long as any bonds or obligations remain outstanding and unpaid and unless and until adequate provision is made by law for the protection of the persons advancing money upon such obligations, the State will not diminish or impair the power of the Department or of any successor thereof to own, operate or control such Bridge and appurtenances or to establish, levy and collect tolls, rents, rates and other charges in connection therewith.