(a) As additional security for the payment of any obligations issued under this subchapter, the commission may execute in favor of the holders of the obligations an indenture, mortgaging and encumbering the improvements, facilities, and properties acquired with the proceeds of the sale of the obligations. The commission may provide in the indenture for a grant to any purchaser, at a foreclosure sale under the indenture, a franchise to operate the improvements, facilities, and properties for a term of not more than 50 years from the date of purchase, subject to all regulatory laws.
(b) The indenture may contain the terms and provisions the commission considers proper and shall be enforceable in the manner provided by the laws of this state for the enforcement of other mortgages and encumbrances.

(c) Under any sale ordered pursuant to the provisions of an indenture, the purchaser and his successors or assigns shall be vested with a permit and franchise to maintain and operate the improvements, facilities, and properties purchased at the sale and shall have the same powers and privileges as could previously have been exercised by the district in the operation of the improvements, facilities, and properties. The purchaser or his successors and assigns may remove all or part of the improvements, facilities, and properties for diversion to other purposes.
(d) Any laws of this state relating to the granting of franchises are not applicable to either the granting of any franchise or authorizing or executing of any mortgage or encumbrance entered into pursuant to the provisions of this subchapter.