S.D. Codified Laws § 1-36-3
The Board of Social Services is hereby continued within the Department of Social Services and shall consist of seven members, not more than four of which may be members of the same political party, appointed by the Governor and subject to removal for cause only. The term of office of each member is three years. The terms of members shall begin on October thirty-first of the calendar year in which the Governor appoints the member, unless otherwise designated by the Governor. The appointee's term expires on October thirtieth in the third year of appointment.
Any member's term ending June 30, 2013, or thereafter is extended to October thirtieth in the year the term is to expire.
A member appointed to fill a vacancy occurring other than by expiration of a term shall be appointed for the unexpired term.
SDCL 1-36-3