S.D. Codified Laws § 38-22-23.12
If a county weed and pest board has probable cause to believe there is land upon which exist weeds or pests that may spread or contribute to the injury or detriment of others, it shall investigate the suspected premises. The designated representative of the board, after giving the landowner written notice, may go upon the premises without interference or obstruction for purposes of making a reasonable investigation of the infested area. Such notice is considered given if it is given to the landowner or operator personally at least one day before entry or if it is mailed, by certified mail, addressed to the last known address of the landowner at least five days before entry. A board may serve notice of intent to inspect on all landowners by publishing a legal notice of such intent at least thirty days before entry in the county's official newspaper.
SDCL 38-22-23.12