S.D. Codified Laws § 10-6-119
The director shall individually assess each tract of real property at its fair market value. In determining the fair market value of property, the director may not adopt a lower or different standard of value because it is to serve as a basis of taxation. The director may not adopt as a criterion of value the price for which a tract of real property would sell at a forced sale, or in the aggregate with all other tracts of real property in the county. The director shall determine the fair market value by appropriate consideration of the cost approach, the market approach, and the income approach to appraisal. The director shall consider and document all elements of such approaches that are applicable prior to a determination of fair market value.
SDCL 10-6-119