Okla. Stat. tit. 82, § 1085.12a

For intrastate or interstate compacts or commissions on which the Executive Director of the Oklahoma Water Resources Board is a member or otherwise is required to perform specified services, the Executive Director, in the event of the Executive Director's temporary absence, may delegate the exercise of such powers and duties to a designee during the Executive Director's absence. In the event of a vacancy in the position of Executive Director, the Board may designate an interim or acting Commissioner and designee who is authorized to exercise such powers and duties until a permanent Executive Director is employed.