Okla. Stat. tit. 82 § 601
At the time of making its order, organizing the district or at any suitable time thereafter; either in term or in vacation the court or judge shall appoint three (3) appraisers, who shall in every case where appraisers are appointed under this act be recommended by the board of directors, and whose duty it shall be to appraise the lands or other property within and without the district to be acquired for rights-of-way, reservoirs and other works of the district and to appraise all benefits and damages accruing to all lands within and without the district by reason of the extension of the official plan. Said appraisers shall be freeholders residing within the counties affected by the district but not interested in said district. Each of the appraisers shall, before taking up his duties, take and subscribe to an oath that he will faithfully and impartially discharge his duties as such appraiser, and that he will make a true report of such work done by him. The said appraisers shall at their first meeting elect one of their own number chairman, and the secretary of the board of directors or his deputy shall be exofficio secretary of said board of appraisers during their continuance in office. A majority of the appraisers shall constitute a quorum and a concurrence of the majority in any matter within their duties shall be sufficient for its determination. Said appraisers shall continue to hold their offices until excused by the court, and the court shall fill all vacancies in the board of appraisers, or may appoint a new board for subsequent appraisals, as occasion may require. Such new board, if appointed, shall fill all the requirements of the board of appraisers and perform its duties.
Provided, that if the court shall find that one board of appraisers cannot appraise the lands and property in said district within reasonable time, then the court may appoint such other boards of appraisers as may be found necessary, specifying their territory of operation.
Okla. Stat. tit. 82, § 601