76-2-112. Effect on powers of incorporated communities to plan adjacent areas. The authority heretofore granted by law to the incorporated communities to approve subdivision plats within the unincorporated area adjacent to their corporate limits is not abrogated by this part except and until the board of county commissioners having jurisdiction over such adjacent area establishes a planning commission and adopts initial regulations for subdivision control within adjacent areas or districts. Authority of the adjacent municipality shall be suspended on the effective date of the county regulation with respect to all areas governed by county subdivision regulations.