Tex. Gov't Code § 1509.210
(a) The governing body of the municipality may impose and collect a charge for the use or availability of:
(b) The governing body shall impose and collect pledged charges in an amount that will be at least sufficient, with any other pledged resource, to provide for the payment of:
(2) to the extent required by the ordinance authorizing the issuance of the bonds:
Added by Acts 1999, 76th Leg., ch. 227, Sec. 1, eff. Sept. 1, 1999.