S.D. Codified Laws § 46A-9-46.1
No portion of any plant or system that is operated by a water user district for the collection, treatment, or disposal of wastewater, including sanitary sewers and sewage and sewage treatment plants and systems, may be located within a zone that extends ten miles outward from the corporate limits of any municipality without the approval of the municipality. However, if the ten-mile zones of more than one municipality overlap, the jurisdiction of each municipality over any such plant or system terminates at a boundary line equidistant from the respective corporate limits of the municipalities; and the water user district shall obtain the approval of each municipality that would have jurisdiction over any portion of the plant or system to be operated by the water user district. The restrictions provided in this section do not apply to any portion of any such plant or system if the portion was in existence on July 1, 2006 or if the portion predates any expansion by a municipality that would otherwise cause the plant or system to be in violation of this section.
SDCL 46A-9-46.1