S.D. Codified Laws § 9-11-6
If a petition signed by fifteen percent of the registered voters of any municipality, as determined by the total number of registered voters at the last preceding general election, is presented to the governing body, requesting that an election be called for the purpose of voting upon a question of change of form of government or upon a question of the number of wards, commissioners, or trustees, the governing body must call an election that must be held within fifty days from the date of the filing of the petition with the municipal finance officer. At that election, the question of the change of form of government or the number of wards, commissioners, or trustees, or both, must be submitted to the voters. No petition is valid if filed more than six months after the circulation start date declared on the petition forms. If the petition is filed on or after January first prior to the annual municipal election and within sufficient time to comply with the provisions of § 9-13-14, the question may be submitted at that annual municipal election.
The election must be held upon the same notice and conducted in the same manner as other municipal elections.
SDCL 9-11-6