Mont. Code § 85-7-2110
A special tax or assessment may not be levied against any 40-acre tract or fractional lot as designated by United States public survey or platted lot, if land is subdivided in lots and blocks (or whenever lands are owned in less than 40-acre tracts or in less than the platted lot, against each such tract) found by the board of commissioners to contain no irrigable land. A lien created after the order of determination may not attach to any nonirrigable tract, nor may the owner or owners of any nonirrigable tract or tracts have any vote or votes in any proceeding or election under the provisions of Chapter 146 of the Laws of 1909 or any amendment thereof or act supplementary thereto, after the making of the order, unless their land or a portion of their land is found by the board to contain an area irrigable from the works or proposed works of the district or subdistrict.
§ 85-7-2110, MCA