S.D. Codified Laws § 49-31-7
In addition to the regulatory powers and duties provided by chapters 49-1 to 49-13, inclusive, and this chapter, the commission may conduct any investigations that are necessary to protect the public interest. The commission may order such changes or improvements in telecommunications facilities, exchanges or networks as necessary for the improvement of telecommunications service and the convenience of the public. If, in the judgment of the commission, any repair upon telecommunications facilities, a change in its rates, a change in the mode of operating telecommunications facilities or conducting telecommunications company business is necessary, reasonable and expedient in order to promote the safety, convenience and accommodation of the public, the commission shall notify the telecommunications company immediately, and such telecommunications company shall change the mode of operating its facilities or conducting its business, or repair, renew or replace such facilities in such manner, of such material and within such time as the commission may order.
SDCL 49-31-7