Tex. Nat. Res. Code § 85.043

If the commission requires a showing that refined products were manufactured from oil legally produced, the requirement shall be of uniform application throughout the state; provided that, if the rule or order is promulgated for the purpose of controlling a condition in any local area or preventing a violation in any local area, then on the complaint of a person that the same or similar conditions exist in some other local area and the promulgation and enforcement of the rule could be beneficially applied to that additional area, the commission may determine whether or not those conditions do exist, and if it is shown that they do, the rule or order may be enlarged to include the additional area.