S.D. Codified Laws § 3-4-8
If any member of a governing body of a county, municipality, school district, township, or special purpose district, who is also a member of the South Dakota National Guard or another reserve component of the armed forces of the United States, is called into active duty which causes the member to be unable to attend meetings of the governing body, the member may elect to temporarily resign from the governing body. Notice of temporary resignation may be given in the same manner as giving notice of resignation from such governing body. A temporary replacement may be made in accordance with the provisions of statute applying to the governing body. The temporary member shall serve until the member returns from active duty or until the expiration of the member's term, whichever occurs first.
SDCL 3-4-8