S.D. Codified Laws § 46A-3B-1
The initial board of directors shall be elected at the next general election following the effective date of an act establishing a water development district. If a general election will not occur within one year after the act goes into effect, the Board of Water and Natural Resources may call a special election for the initial board of directors, the costs of such special election to be borne by the water development district. The initial directors shall be elected to serve for staggered terms until the January first following the first general election that occurs at least twelve months after the initial election or the next succeeding general election respectively to represent areas of the water development district. Directors shall thereafter be elected to four-year terms at each subsequent general election to succeed those directors whose terms expire at the end of the year in which the election is held.
SDCL 46A-3B-1