S.D. Codified Laws § 41-18-3

If three hundred or more freehold voters of any county file with the county auditor a petition setting forth that certain real property, therein described, within the county is desirable for the purposes of a public park and that it would be to the benefit of the public that the property be acquired for such purpose, the auditor shall file the petition and shall fix a day for hearing the petition by the county commissioners, not less than twenty nor more than forty days from the filing. Upon the date set for the hearing, the county commissioners shall hear all parties in favor of and against the granting of the petition.