S.D. Codified Laws § 49-34-11.3
A mortgage or trust deed to secure a debt executed by a public utility as defined in § 49-34-11.1, covering the whole or part of its easements or other less than fee simple interests in real estate used in the transmission or distribution of gas or electric service, and also covering the fixtures of the public utility which are annexed to it, may be filed in the office of the secretary of state along with, or as part of, the financing statement covering the fixtures. The filing of the mortgage or deed of trust has the same effect, and is notice of the rights and interest of the mortgagee or trustee in the easements and other less than fee simple interest in real estate to the same extent, as if the mortgage or deed of trust were duly recorded in the office of the register of deeds of the counties in which the real estate is situated. The effectiveness of the filing will terminate at the same time as provided § 49-34-11.2 for the termination of the effectiveness of a fixture filing. For the purpose of this section, a mortgage or deed of trust filed under this section contains a sufficient description to give notice of the rights and interest of the mortgagee or trustee in the easements and other less than fee simple interest in the real estate used for the transmission and distribution of gas or electric service of the public utility if the mortgage or deed of trust states that the security includes rights-of-way of, or transmission or distribution systems of, or lines of, the public utility, or all property owned by the public utility. A mortgage or deed of trust filed before July 1, 1989, pursuant to § 49-34-11, which complies with the provisions of this section, is filed under this section as of July 1, 1989. Section 49-34-11 applies to real estate owned in fee simple by a public utility.
SDCL 49-34-11.3