Tex. Water Code § 55.251

The district may employ and constitute its own peace officers. The peace officers may make arrests when necessary to prevent or abate the commission of an offense against the regulations of the district or state laws if the offense occurs or is about to occur on land or water owned or controlled by the district. Arrests also may be made any place where an offense is being committed which involves injury or detriment to any property owned or controlled by the district.