S.D. Codified Laws § 7-21-51
A board of county commissioners may, by resolution, authorize the accumulation of funds for a period longer than one year for a capital outlay purpose which is otherwise authorized by law. For the purpose of this section, the term, capital outlay purpose, includes any purpose which is extraordinary in nature, exceeds the funding ability of a single-budget year, and may result in the purchase of services, materials, supplies, or equipment. The resolution is enacted if approved by a vote of sixty percent or more of the governing body and shall clearly set forth the purposes for which the funds are to be accumulated and the maximum amount that may be accumulated. The funds to be accumulated shall be expended within eighty-four months from the date of the resolution. If the specific purpose for which the funds are accumulated is no longer necessary, the funds shall revert to the fund from which the funds were originally appropriated. The amount of accumulation for a specific purpose may not exceed five million dollars. The accumulation of funds pursuant to this chapter is in addition to any accumulation of funds authorized by § 7-21-18.1.
SDCL 7-21-51