Tex. Water Code § 35.004

(a) The Texas Water Development Board, with assistance and cooperation from the commission, shall designate groundwater management areas covering all major and minor aquifers in the state. The initial designation of groundwater management areas shall be completed not later than September 1, 2003. Each groundwater management area shall be designated with the objective of providing the most suitable area for the management of the groundwater resources. To the extent feasible, the groundwater management area shall coincide with the boundaries of a groundwater reservoir or a subdivision of a groundwater reservoir. The Texas Water Development Board also may consider other factors, including the boundaries of political subdivisions.

(b) The commission may designate a groundwater management area after September 1, 2001, for a petition filed and accepted by the commission according to its rules in effect before September 1, 2001. The commission shall act on the designation in accordance with this section.

(c) The Texas Water Development Board may alter the boundaries of designated management areas as required by future conditions and as justified by factual data. An alteration of boundaries does not invalidate the previous creation of any district.

(d) The Texas Water Development Board shall designate groundwater management areas using the procedures applicable to rulemaking under Chapter 2001, Government Code.