Tex. Water Code § 56.0642
Subsection (b) of Section 56.064 and Section 56.0641 of this code apply to drainage districts created or governed by special law where the special law expressly adopts the provisions of Section 56.064 of this code or its predecessor statute (Article 8119, Revised Civil Statutes of Texas, 1925) or repeats its provisions, without change in substance, as those provisions existed at the time the special law was enacted; but they do not apply to any district established, reestablished, or otherwise affected by special law where the special law contains specific provisions relating to the method of selecting the governing body of the district which were at variance with the provisions of Section 56.064 of this code or its predecessor at the time the special law was enacted.
Tex. Water Code § 56.0642