Texas Government Code - GOV'T § 1507.051. Authority to Issue Refunding Bonds

(a) The governing body of a municipality by ordinance may issue refunding bonds in accordance with Subchapters A and D, Chapter 1207, to refund outstanding refunding bonds if:

(b) The governing body of a municipality that issues bonds under this subchapter to refund revenue bonds may secure the bonds issued under this subchapter by a deed of trust on the municipality's utility system or by a pledge of the net revenue of the system if the bonds being refunded provide for that pledge.