S.D. Codified Laws § 31-11-6
The county highway superintendent shall keep a detailed record of the cost of any work on any section of the highway, bridge, tile, or culvert construction, repair work, or materials therefor done under his supervision by the county, by day labor and shall immediately upon the completion of each piece of work file the record with the county auditor, showing in detail the cost of all labor, materials, repairs, repair materials, hauling, inspection costs, and a proper proportion of the yearly equipment depreciation and repair charges for the county road building equipment, rental of machinery and every other item of cost. However, the county auditor may destroy any record which the records destruction board, acting pursuant to § 1-27-19, declares to have no further administrative, legal, fiscal, research, or historical value.
SDCL 31-11-6