S.D. Codified Laws § 31-13-13
The board of supervisors of any township may jointly contract with the county of which the township is a part, and also with any municipality within or adjoining the township, for the laying out, construction, graveling, hard surfacing, or maintenance of designated township roads. The agreement shall designate the governing board to be charged with contracting for performance of the work, provide for supervision of the work and allocate the costs between the units of government participating. The board of township supervisors may also contract with any other political subdivision, homeowners' association, or rural subdivision developer to perform maintenance work on any road that is not on the township road system. Maintenance work performed on a road under contract does not imply dedication or acceptance of the road to the township road system.
SDCL 31-13-13