S.D. Codified Laws § 49-37-9
Before any consumers power district enters into any contract for the construction, building, alteration, extension, or improvement of any power plant or system, or any part or section thereof, for the use of the district, or for the purchase of any materials, machinery, or equipment, excluding the purchase of electric power and energy, the district shall cause estimates of the cost thereof to be made by a competent engineer. If the estimated cost exceeds the sum of fifty thousand dollars, no contract may be entered into without advertising for sealed bids. However, this section does not apply to any consumers power district if the district, jointly with others, contracts for construction, building, alteration, extension, improvement, or leasing of any power plant or system. As far as practicable the board of directors shall secure at least two competitive quotations and retain them for their files. The board shall enter in the minutes a statement of the quotations received, identifying the bidder and the amount of the bid.
SDCL 49-37-9