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.
Tex. Water Code § 7.256