(a) The commission by rule shall:
(1) adopt appropriate environmental flow standards for each river basin and bay system in this state that are adequate to support a sound ecological environment, to the maximum extent reasonable considering other public interests and other relevant factors;
(2) establish an amount of unappropriated water, if available, to be set aside to satisfy the environmental flow standards to the maximum extent reasonable when considering human water needs; and
(3) establish procedures for implementing an adjustment of the conditions included in a permit or an amended water right as provided by Sections 11.147(e-1) and (e-2).
(b) In adopting environmental flow standards for a river basin and bay system under Subsection (a)(1), the commission shall consider:
(1) the definition of the geographical extent of the river basin and bay system adopted by the advisory group under § 11.02362(a) and the definition and designation of the river basin by the board under § 16.051(c);
(2) the schedule established by the advisory group under § 11.02362(d) or (e) for the adoption of environmental flow standards for the river basin and bay system, if applicable;
(3) the environmental flow analyses and the recommended environmental flow regime developed by the applicable basin and bay expert science team under § 11.02362(m);
(4) the recommendations developed by the applicable basin and bay area stakeholders committee under § 11.02362(o) regarding environmental flow standards and strategies to meet the flow standards;
(5) any comments submitted by the advisory group to the commission under § 11.02362(q);
(6) the specific characteristics of the river basin and bay system;
(7) economic factors;
(8) the human and other competing water needs in the river basin and bay system;
(9) all reasonably available scientific information, including any scientific information provided by the science advisory committee; and
(10) any other appropriate information.

(c) Environmental flow standards adopted under Subsection (a)(1) must consist of a schedule of flow quantities, reflecting seasonal and yearly fluctuations that may vary geographically by specific location in a river basin and bay system.
(d) As provided by § 11.023, the commission may not issue a permit for a new appropriation or an amendment to an existing water right that increases the amount of water authorized to be stored, taken, or diverted if the issuance of the permit or amendment would impair an environmental flow set-aside established under Subsection (a)(2). A permit for a new appropriation or an amendment to an existing water right that increases the amount of water authorized to be stored, taken, or diverted that is issued after the adoption of an applicable environmental flow set-aside must contain appropriate conditions to ensure protection of the environmental flow set-aside.
(e) An environmental flow set-aside established under Subsection (a)(2) for a river basin and bay system other than the middle and lower Rio Grande must be assigned a priority date corresponding to the date the commission receives environmental flow regime recommendations from the applicable basin and bay expert science team and be included in the appropriate water availability models in connection with an application for a permit for a new appropriation or for an amendment to an existing water right that increases the amount of water authorized to be stored, taken, or diverted.
(f) An environmental flow standard or environmental flow set-aside adopted under Subsection (a) may be altered by the commission in a rulemaking process undertaken in accordance with a schedule established by the commission. The commission shall consider the review of environmental flow standards by the advisory group under § 11.02363(a) when altering an environmental flow standard or environmental flow set-aside. In establishing a schedule, the commission shall consider the work plan developed by the advisory group under § 11.02363(b) and the applicable work plan approved by the advisory group under § 11.02362(p). The commission’s schedule may not provide for the rulemaking process to occur more frequently than once every 10 years unless the work plans provide for a periodic review under Sections 11.02363(a) and 11.02362(p) to occur more frequently than once every 10 years. In that event, the commission may provide for the rulemaking process to be undertaken in conjunction with the periodic review if the commission determines that schedule to be appropriate. A rulemaking process undertaken under this subsection must provide for the participation of stakeholders having interests in the particular river basin and bay system for which the process is undertaken.
(g) The commission shall submit a biennial report to the advisory group on the implementation and effectiveness of environmental flow standards. The report must include:
(1) a description of progress made over the previous biennium in implementing environmental flow standards, including the status of any efforts to set aside unappropriated water for environmental flow protection;
(2) input provided by the board and the Parks and Wildlife Department on their:
(A) activities related to environmental flow standards; and
(B) recommendations for the work plan developed under § 11.02363(b); and
(3) recommendations for the work plan developed under § 11.02363(b).