S.D. Codified Laws § 5-18C-6
The bid requirements of this chapter and chapters 5-18A, 5-18B, and 5-18D do not apply to the purchase of fuel by units of local government. The governing board of a unit of local government may, instead of advertising for bids, negotiate a contract for the purchase of fuel at the most advantageous price. The governing board shall contact and attempt to obtain competitive quotations from at least three suppliers. A record of the names of the suppliers, the quotations received and the procurement procedures used in purchasing shall be documented, noted in the minutes, and retained on file by the governing body. The contract may include a procedure for adjusting prices to meet changing market conditions not within the control of the vendor.
SDCL 5-18C-6