S.D. Codified Laws § 49-34A-55
Nothing contained in §§ 49-34A-42 to 49-34A-44, inclusive, and 49-34A-48 to 49-34A-57, inclusive, prohibits electric utilities from buying, selling, or exchanging electric distribution properties, service rights and other rights, property, and assets by mutual agreement, subject to approval of the commission. Any agreement, pursuant to this section, which changes assigned service areas shall be filed and approved by the commission before it may become effective. The commission's approval of such agreements shall be based on the public interest. The factors to consider shall include the elimination or avoidance of unnecessary duplication of facilities, providing adequate electric service to all areas and customers affected, and the promotion of the efficient and economical use and development of the electric systems of the contracting electric utilities.
SDCL 49-34A-55