S.D. Codified Laws § 32-14-6
Local authorities, including road districts, may by ordinance or resolution prohibit the operation of vehicles upon any highway or impose restrictions as to the weight of vehicles allowed. Such prohibitions or restrictions apply only to vehicles to be operated upon any highway under the jurisdiction of and for the maintenance of which such local authorities are responsible and only if the highway by reason of physical condition, rain, snow, or other climatic conditions will be seriously damaged or destroyed unless the use of vehicles on the highway is prohibited or the permissible weights of the vehicles are reduced. Any local authority enacting any such ordinance or resolution shall erect and maintain or cause to be erected and maintained signs designating the provisions of the ordinance or resolution at each end of that portion of any highway affected by the ordinance or resolution. The ordinance or resolution is not valid unless such signs are erected and maintained.
SDCL 32-14-6