S.D. Codified Laws § 31-19-19
Whenever any land, easement in land or material is necessary for right-of-way in order to make a safe or proper grade, for the relocating of utility facilities, or for widening, changing, relocating, constructing, reconstructing, maintaining, or repairing any portion of the state trunk highway, or if it is necessary for providing cut slopes, borrow pits, channel changes, or to afford unobstructed vision on any state trunk highway and at any point of danger to public travel, for right-of-way and borrow pit, the State of South Dakota, through and by its Department of Transportation, or any county authorized by agreement to acquire on behalf of the state, shall acquire and pay for the same out of state highway funds unless it is otherwise agreed. The cost of the land or material and expense of purchase or condemnation shall be paid as part of the cost of the state trunk highway unless otherwise agreed.
SDCL 31-19-19