S.D. Codified Laws § 49-37-16

The board of directors of any district organized under chapter 49-35 shall have the power and be required to fix, establish and collect adequate rates, tolls, rents, and other charges, for electrical energy, and for any services or facilities sold, furnished or supplied by the district, which rates, tolls, rents, and charges shall be fair, reasonable, nondiscriminatory, and so adjusted as in a fair and equitable manner to confer upon and distribute among the users and consumers of services furnished or sold by the district the benefits of a successful operation and conduct of the business of the district.