S.D. Codified Laws § 10-12-13
The board of county commissioners may levy an annual tax as a reserve fund to be accumulated and used for the purpose of maintaining, repairing, constructing, and reconstructing roads and bridges as follows:
Money in the fund may be expended in the laying out, marking, maintaining, constructing, and reconstructing roads and maintaining, constructing, and reconstructing bridges, under the jurisdiction of the board of county commissioners. The tax levy shall be in addition to all other levies authorized to be made by the board of county commissioners for road and bridge purposes provided for in § 10-12-21. The proceeds of such levy shall be placed in a special fund to be known as the county highway and bridge reserve fund. Any increased tax levy imposed pursuant to this section is exempt from the provisions of chapter 10-13, if the county establishes the amount of revenue payable from taxes on real property pursuant to § 10-12-13.1.
The total amount of revenue payable from any increased tax levy imposed pursuant to this section may increase no more than the lesser of three percent or the index factor, as defined in § 10-13-38, over the amount of revenue payable in the preceding year. After applying the index factor, a county may increase the revenue payable from taxes on real property above the limitations provided by this section by the percentage increase of value resulting from any improvements or change in use of real property and any adjustments in taxation of property separately classified and subject to statutory adjustments and reductions under chapters 10-4, 10-6, 10-6A, and 10-6B, except § 10-6-113, only if assessed the same as property of equal value.
SDCL 10-12-13