S.D. Codified Laws § 31-13-1
The board of township supervisors shall construct, repair, and maintain all of the township roads within the township except for section lines designated as no maintenance section lines pursuant to § 31-13-1.4 and roads designated as no maintenance roads pursuant to § 31-13-1.6. The township road system consists of section line roads; judicially declared roads; roads impliedly accepted by the township through routine performance of certain maintenance activities, such as grading, graveling and snow removal, and accepting funds from the county pursuant to §§ 32-11-4.1 and 32-11-6 for a period of at least fifteen years; and any other roads designated by resolution of the board as being on the township road system. A road may only be vacated through the process specified in chapter 31-3. Before a road may be added to the township road system, the road shall meet the minimum requirements specified in §§ 31-18-2 and 31-13-4, unless the board, by resolution, waives this requirement.
SDCL 31-13-1