S.D. Codified Laws § 10-35-10.1
For the purpose of determining the fair market value of the property of any public utility company, the Department of Revenue shall take into consideration the cost approach, the market approach, and the income approach to appraisal. In the market approach, the department shall consider the actual or market value of the shares of stock outstanding, the actual or market value of all bonds outstanding, and all other indebtedness as may be applicable for operating the company. In the income approach, the department may consider the company's growth rate and the rate of inflation in determining the capitalization rate. The Department of Revenue may take into consideration any other information or data of any kind or nature which the department may deem material in arriving at the fair market value of the property.
SDCL 10-35-10.1