S.D. Codified Laws § 11-4-24
In lieu of appointing the board of adjustment provided by § 11-4-13, the governing body of any municipality having adopted and effectuated a zoning ordinance may act as and perform all the duties and exercise the powers of such board of adjustment. Whenever the governing body is acting as the board of adjustment, the mayor or president of the board of trustees is chairman of the board of adjustment. The concurring vote of at least two-thirds of the members of such board shall be necessary to reverse any order, requirement, decision, or determination of any administrative official, or to decide in favor of the appellant on any matter upon which it is required to pass under any zoning ordinance, or to effect any variation in such ordinance.
SDCL 11-4-24