(a) A right to take and use water is limited to the extent and purposes authorized in the water right. Except as specifically provided otherwise in the water right, state water appropriated under a water right may be beneficially used and reused by the water right holder in accordance with the water right prior to its release into a watercourse or stream. Once water has been diverted under a water right and then returned to a watercourse or stream, however, it is considered surplus water and, therefore, subject to maintaining instream uses, beneficial inflows to bays and estuaries, or appropriation by others unless expressly provided otherwise in the water right.     
      (b) A person who takes or diverts water from a watercourse or stream shall conduct surplus water back to the watercourse or stream from which it was taken if the water can be returned by gravity flow and it is reasonably practicable to do so. In addition, the commission may include in the water right a specific amount or percentage of water diverted to be returned and the return point on the stream or watercourse, if necessary to protect senior downstream water rights or to provide flows for instream uses and bays and estuaries.     
      (c) Return waters must meet water quality standards provided by Chapter 307 of this title  (relating to Texas Surface Water Quality Standards) prior to their discharge into water in the state. Additionally, such discharge shall not impair an existing or potential beneficial use of groundwater as to its water quality. Nothing in this chapter affects the obligation to obtain a permit under Texas Water Code Chapter 26, if required.     
      (d) Water appropriated under a water right that is recirculated within a reservoir for cooling purposes shall not be considered to be surplus for purposes of this section.     
     Source Note:        The provisions of this §297.49 adopted to be effective February 24, 1999, 24 TexReg 1162