S.D. Codified Laws § 10-35-3

It shall be the duty of the president, secretary, general manager, or superintendent of every light and power company, heating company, water company, and natural or artificial gas company doing business in this state, to furnish to the Department of Revenue, on or before April fifteenth each year, a report under oath, on the forms furnished and according to the instructions issued by the Department of Revenue, with reference to the property owned, leased, or controlled on December thirty-first of the calendar year preceding the year for which the report is made.