(1) The department shall divide the state into forest valuation zones, with each zone designated to recognize the uniqueness of marketing areas, timber types, growth rates, access, and other pertinent factors that affect value. The designated forest valuation zones and the counties contained within each zone are:

(a) Zone 1 - Northwest: Flathead, Lake, Lincoln, and Sanders counties;

(b) Zone 2 - Southwest: Beaverhead, Deer Lodge, Granite, Jefferson, Madison, Mineral, Missoula, Powell, Ravalli, and Silver Bow counties;

(c) Zone 3 - Central: Blaine, Broadwater, Cascade, Chouteau, Fergus, Gallatin, Glacier, Golden Valley, Hill, Judith Basin, Lewis and Clark, Liberty, Meagher, Park, Pondera, Teton, Toole, and Wheatland counties;

(d) Zone 4 - Eastern: Big Horn, Carbon, Carter, Custer, Daniels, Dawson, Fallon, Garfield, McCone, Musselshell, Petroleum, Phillips, Powder River, Prairie, Richland, Roosevelt, Rosebud, Sheridan, Sweet Grass, Stillwater, Treasure, Valley, Wibaux, and Yellowstone counties.