Texas Government Code - GOV'T § 441.129. Withdrawal from System

(a) The governing body of a political subdivision of the state may by resolution or ordinance withdraw from a major resource system.  The governing body must give notice of withdrawal not later than the 90th day before the end of the state fiscal year.

(b) The provision for termination of all or part of a major resource system does not prohibit revision of the system by the commission, with the approval of the majority of the appropriate governing bodies, by reorganization, by transfer of part of the system, or by merger with other systems.