S.D. Codified Laws § 38-7-5
One conservation district supervisor member shall be at-large and one conservation district supervisor member from each of the three conservation district supervisor member areas shall be appointed to the commission. This state is divided into three conservation district supervisor member areas as follows: all of that area east of the Missouri River and north of the southern boundaries of Hughes, Hyde, Hand, Beadle, Kingsbury, and Brookings counties shall be known and designated as Area I; all of that area east of the Missouri River and south of the northern boundaries of Buffalo, Jerauld, Sanborn, Miner, Lake, and Moody counties shall be known and designated as Area II; and all of that area west of the Missouri River shall be known and designated as Area III.
SDCL 38-7-5