S.D. Codified Laws § 46A-4-64

In case of the inclusion of any land within any district by proceedings under this chapter, the board of directors shall, at least thirty days before the next succeeding general election, make an order redividing the district into three, five, or seven divisions, as nearly equal in size as may be practicable. The divisions shall be numbered, and one director shall thereafter be elected by each division. For the purposes of elections the board of directors shall establish a convenient number of election precincts in the district and define the precinct boundaries. The precincts may be changed from time to time as the board deems necessary.