S.D. Codified Laws § 46A-3A-14
If in some, but not all of the election districts within a proposed water development district, sixty percent or more of the votes cast are in favor of the formation of the water development district, the Board of Water and Natural Resources shall by resolution establish a water development district consisting of only those election districts wherein the requisite vote approving the formation of a water development district was cast. In the event of the creation of a water development district, any of the election districts may withdraw from the water development district by filing with the board within sixty days thereafter, a petition requesting withdrawal, signed by fifteen percent of the residents and voters in the election district. The petition shall contain the same information with respect to the signers and be verified in the same manner as in the case of a petition to establish a water development district. The question of whether an election district shall withdraw shall be referred to the voters of the election district at the next general election, the procedure is the same as required to establish a water development district.
SDCL 46A-3A-14