Tex. Water Code § 7.256

If a person can establish that an act or event that otherwise would be a violation of a statute within the commission's jurisdiction or a rule adopted or an order or permit issued by the commission under such a statute was caused solely by compliance with the general duty clause of the federal Occupational Safety and Health Act of 1970 (29 U.S.C. Section 654), the act or event is not a violation of that statute, rule, order, or permit.