S.D. Codified Laws § 31-12-41
Counties are authorized to contract with municipalities within their respective boundaries for the maintenance of public streets and alleys or any portion thereof within said municipalities. Whenever it shall be made to appear to the board of county commissioners of any county by a resolution of any municipality within the county, duly adopted, copy of which resolution shall be filed in the office of the county auditor of the county of which such municipality is located that it will be to the best interests of such municipality and in the public interest that the municipality enter into an agreement in writing with the board of county commissioners of such county for the maintenance of any public street or alley or any portion thereof, the board of county commissioners may, in its discretion, enter into an agreement in writing with the governing body of such municipality to maintain any such street or alley, to be specifically designated, at and for a price to be paid to the county to be expressed in the agreement for such maintenance. If it shall appear to the board of county commissioners that it will be to the public interest to enter into such an agreement, it shall be lawful for it so to do, and such county, by and through its highway department and with the personnel and equipment thereof, perform, or cause to be performed, for such municipality such maintenance specified in said agreement and such maintenance to be done under the supervision and control of the county highway superintendent. The prices specified in said contract shall be paid to the said county by the municipality upon estimates certified to by the county highway superintendent in the same manner as other obligations of the municipality are paid.
SDCL 31-12-41