S.D. Codified Laws § 49-34A-44
On or before January 1, 1976, or, when requested in writing by an electric utility and for good cause shown, and at a further time as the Public Utilities Commission may fix by order, each electric utility shall file with the commission a map or maps showing all its electric lines outside of incorporated municipalities as they existed on March 21, 1975. Each electric utility shall also submit in writing a list of all municipalities in which it provided electric service on March 21, 1975. Where two or more electric utilities serve a single municipality, the commission may require each utility to file with the commission a map showing its electric lines within the municipality.
On or before July 1, 1976, the commission shall, after notice and hearing, establish the assigned service area or areas of each electric utility and shall prepare or cause to be prepared a map or maps to accurately and clearly show the boundaries of the assigned service area of each electric utility.
In those areas where, on March 21, 1975, the existing electric lines of two or more electric utilities were so intertwined that § 49-34A-43 cannot reasonably be applied, the commission shall, after hearing, determine the boundaries of the assigned service areas for the electric utilities involved. In making its decision, the commission shall be guided by the following conditions as they existed on March 21, 1975:
Any electric utility which feels itself aggrieved by reason of an assignment of a service area may protest such assignment within a ninety-day period after issuance of the map of the assigned service areas by the commission and the commission shall have the power, after hearing, to revise or vacate such assigned service area or portions thereof consistent with the provisions of this section and § 49-34A-43.
SDCL 49-34A-44