S.D. Codified Laws § 34-31A-13
Permanent organization shall be effected by the election of a board of directors consisting of not less than five residents of the district. If the district includes any incorporated municipalities which are located within the boundaries of the district, no more than two members of a five-member board of directors may be voters who are residents of the incorporated municipal areas of the district if at least forty percent of the registered voters of the district live outside the incorporated areas of the district, and no more than three members of the board of directors may be voters who are residents of the incorporated municipal areas of the district if at least twenty percent of the registered voters of the district live outside the incorporated areas of the district. If the board of directors consists of more than five members, the additional members, as nearly as can be accomplished, shall be in the proportions set forth in this section.
SDCL 34-31A-13