S.D. Codified Laws § 46A-9-27

The board of directors, at least twenty days before the date of election, shall mail to each person or corporation entitled to vote at the election, at the person's or corporation's last known place of residence or business, a notice stating the time, place, and purpose of the election. Alternatively, the board may publish in each county in which lands within the district lie, in some newspaper of general circulation printed and published in the county, once each week for at least two successive weeks before the time of election, a notice that the election will be held and giving the purpose, time, and place.