Montana Title 75. Environmental Protection § 75-26-403. Wind turbine generator deicing--requirement

(1) 500 feet or more in height, as measured from the natural ground level at the base of the tower to the tip of the turbine rotor blade;

(2) constructed within an area with an ice class rating of 4 or more, as defined in international energy agency guidelines published in February 2017;  and

(3) located within a distance of 1,500 feet from an occupied residence.