70-22-205. Technical description of zones. For purposes of more precisely defining the Montana coordinate systems NAD 27 and NAD 83, the following description by the national ocean survey/national geodetic survey (formerly the United States coast and geodetic survey) is adopted:
     (1) The Montana coordinate system NAD 27, north zone, is a Lambert conformal projection of the Clarke spheroid of 1866, having standard parallels at north latitudes 47º 51"' and 48º 43"', along which parallels the scale shall be exact. The origin of coordinates is at the intersection of the meridian 109º 30"' west of Greenwich and the parallel 47º 00"' north latitude. This origin is given the coordinates: x = 2,000,000 feet and y = 0 feet.
     (2) The Montana coordinate system NAD 27, central zone, is a Lambert conformal projection of the Clarke spheroid of 1866, having standard parallels at north latitudes 46º 27"' and 47º 53"', along which parallels the scale shall be exact. The origin of coordinates is at the intersection of the meridian 109º 30"' west of Greenwich and the parallel 45º 50"' north latitude. This origin is given the coordinates: x = 2,000,000 feet and y = 0 feet.
     (3) The Montana coordinate system NAD 27, south zone, is a Lambert conformal projection of the Clarke spheroid of 1866, having standard parallels at north latitudes 44º 52"' and 46º 24"', along which parallels the scale shall be exact. The origin of coordinates is at the intersection of the meridian 109º 30"' west of Greenwich and the parallel 44º 00"' north latitude. This origin is given the coordinates: x = 2,000,000 feet and y = 0 feet.
     (4) The Montana coordinate system NAD 83 is a Lambert conformal conic projection of the GRS 80 (Geodetic Reference System 1980) ellipsoid, having standard parallels of north latitudes 45º 00"' and 49º 00"', along which parallels the scale shall be exact. The origin of coordinates is at the intersection of the meridian 109º 30"' west of Greenwich and the parallel 44º 15"' north latitude. This origin is given the coordinates: x = 600,000 meters and y = 0 meters.

     History: En. Sec. 5, Ch. 232, L. 1965; amd. Sec. 2, Ch. 73, L. 1975; R.C.M. 1947, 67-2015; amd. Sec. 5, Ch. 137, L. 1987.