Tex. Water Code § 51.532
If a city, town, or municipal corporation is constituted a district operating under this chapter, taxes levied in the district may be assessed and collected in the manner provided in Sections 51.533-51.538 of this code.
Acts 1971, 62nd Leg., p. 355, ch. 58, Sec. 1, eff. Aug. 30, 1971.