S.D. Codified Laws § 31-22-1
Every owner of an isolated tract of land containing at least ten acres not touched by a passable public highway or smaller tract of land containing at least five acres used or intended to be used in good faith in whole or in part for residential purposes is entitled to an easement or right-of-way across adjacent lands to reach a public highway, which easement or right-of-way may be secured as provided in this chapter. An isolated tract is further defined as an area which is either inaccessible by motor vehicle because of natural barriers from all other land owned by the owner of the isolated tract or is such an area which is not touched by a passable public highway, which is in use or reasonably usable for motor vehicles. A tract of land adjoining a section line right-of-way for at least sixty-six feet is not an isolated tract if a passable road can be built within the adjoining section line to connect to a passable public highway.
SDCL 31-22-1