S.D. Codified Laws § 31-26-12
If the applicant in the case of a transmission application, wishes to construct lines or bury underground cable for rural electrification the applicant may state that the applicant wishes to construct lines for rural electrification throughout the county, in which event the applicant need not show the point or points to which the applicant desires to transmit electricity nor the route, and if the application is granted to such applicant for rural electrification county-wide authorization may be given to such applicant but subject to the other provisions of this chapter. For the purposes of this chapter, a line or underground cable shall be deemed "for rural electrification" if it carries at least one circuit of such voltage as is practical for and customarily used in distributing electricity to farms.
SDCL 31-26-12