S.D. Codified Laws § 1-1-13
No assumption of civil or criminal jurisdiction shall become effective under the provisions of §§ 1-1-12 to 1-1-16, inclusive, until the tribal council of a tribe over which state jurisdiction is to be taken, shall have considered a referendum in which all persons eligible to vote at elections held for the purposes of electing officers of such tribe, shall have been given an opportunity to approve or disapprove such assumption of jurisdiction. A majority of the persons so voting in such a referendum must cast affirmative votes in favor thereof before such approval shall be given, and the tribal council shall then notify the board of county commissioners of the counties concerned as to the results of such referendum. Provided, however, that if the tribe has failed to take action as above prescribed, within one year from and after October first, 1957, it shall be deemed that the referendum has been dispensed with and that the tribe has consented to and does approve the assumption of jurisdiction herein provided, and that the county or counties concerned may then proceed as set forth in § 1-1-14.
SDCL 1-1-13