There are at least 115 named Islands in Montana. These islands occur in rivers, lakes and reservoirs.

Islands east of the Continental Divide Missouri River Archers Island, Chouteau County, Montana, , el. Baker Bar, Chouteau County, Montana, , el. Boggs Island, Chouteau County, Montana, , el. Brule Bar, Chouteau County, Montana, , el. Buckshot Island, Cascade County, Montana, , el. Chelsea Island, Roosevelt County, Montana, , el. Council Island, Chouteau County, Montana, , el. Cow Island, Blaine County, Montana, , el. Crow Coulee Bar, Chouteau County, Montana, , el. Duck Island, Valley County, Montana, , el. Evans Bend, Chouteau County, Montana, , el. Fisher Island, Cascade County, Montana, , el. Grand Island, Phillips County, Montana, , el. Holmes Council Islands, Fergus County, Montana, , el. Iron City Islands, Fergus County, Montana, , el. Jones Island, Phillips County, Montana, , el. King Island, Fergus County, Montana, , el. Lower Two Calf Island, Phillips County, Montana, , el. Nelson Island, Cascade County, Montana, , el. PN Island, Fergus County, Montana, , el. Park Island, Cascade County, Montana, , el. Pine Island, Cascade County, Montana, , el. Pablo Island, Chouteau County, Montana, , el. Roosevelt Island, Chouteau County, Montana, , el. Sacajawea Island, Cascade County, Montana, , el. Scout Island, Valley County, Montana, , el. Shonkin Bar, Chouteau County, Montana, , el. Skinners Island, Roosevelt County, Montana, , el. Steamboat Island, Cascade County, Montana, , el. Sturgeon Island, Blaine County, Montana, , el. Taylor Island, Cascade County, Montana, , el. Three Islands, Chouteau County, Montana, , el. Upper Two Calf Island, Phillips County, Montana, , el. White Shield Island, Roosevelt County, Montana, , el. Wolf Island, Chouteau County, Montana, , el. Yorks Islands, Broadwater County, Montana, , el.

Yellowstone River Beaver Island, Richland County, Montana, , el. Big Marys Island, Yellowstone County, Montana, , el. Breakneck Island, Richland County, Montana, , el. Buella Island, Richland County, Montana, , el. Cherry Island, Yellowstone County, Montana, , el. Chrome Island, Wibaux County, Montana, , el. Crittenden Island, Richland County, Montana, , el. Devils Island, Richland County, Montana, , el. Diamond Island, Richland County, Montana, , el. Dovers Island, Yellowstone County, Montana, , el. Duck Island, Richland County, Montana, , el. Elk Island, Richland County, Montana, , el. Elms Island, Richland County, Montana, , el. Government Island, Yellowstone County, Montana, , el. Gros Ventre Island, Richland County, Montana, , el. Idiom Island, Richland County, Montana, , el. Howery Island, Treasure County, Montana, , el. Joes Island, Dawson County, Montana, , el. Livingston Island, Park County, Montana, , el. Marys Island, Richland County, Montana, , el. Monroe Island, Dawson County, Montana, , el. Pirogue Island, Custer County, Montana, , el. Randalls Island, Yellowstone County, Montana, , el. Schaffer Island, Dawson County, Montana, , el. Seven Sisters Island, Richland County, Montana, , el. Siebeck Island, Park County, Montana, , el. Snake Island, Richland County, Montana, , el. Spraklin Island, Yellowstone County, Montana, , el. Westover Island, Carbon County, Montana, , el.

Other waters east of the divide Big Island, Sheridan County, Montana, , el. in Medicine Lake Bruces Island, Sheridan County, Montana, , el. in Medicine Lake Far West Island, Big Horn County, Montana, , el. in the Big Horn River Fire Island, Sweet Grass County, Montana, , el. in the Boulder River Gull Island, Sheridan County, Montana, , el. in Medicine Lake Long Island, Phillips County, Montana, , el. in Lake Bowdoin Lovell Island, Beaverhead County, Montana, , el. in the Beaverhead River Pelican Islands, Phillips County, Montana, , el. in Lake Bowdoin Smith Island, Beaverhead County, Montana, , el. in the Beaverhead River The Island, Carter County, Montana, , el. in the Little Missouri River Thunderbird Island, Glacier County, Montana, , el. in Saint Mary Lake Youngs Island, Sheridan County, Montana, , el. in Medicine Lake Wild Goose Island, Glacier County, Montana, , el. in Saint Mary Lake Woody Island, Phillips County, Montana, , el. in Lake Bowdoin York Island, Garfield County, Montana, , el. in Fort Peck Lake

Islands west of the Continental Divide Flathead Lake Bird Island, Lake County, Montana, , el. Bull Island, Lake County, Montana, , el. Cedar Island, Lake County, Montana, , el. Cromwell Island, Lake County, Montana, , el. Douglas Islands, Lake County, Montana, , el. Dream Island, Lake County, Montana, , el. Goose Island, Lake County, Montana, , el. Invitation Island, Flathead County, Montana, , el. Melita Island, Lake County, Montana, , el. Little Bull Island, Lake County, Montana, , el. Mary B Island, Lake County, Montana, , el. Rock Island, Lake County, Montana, , el. Shelter Island, Lake County, Montana, , el. Wild Horse Island, Lake County, Montana, , el.

Hungry Horse Reservoir Clayton Island, Flathead County, Montana, , el. Elk Island, Flathead County, Montana, , el. Fire Island, Flathead County, Montana, , el. Kelly Island, Flathead County, Montana, , el. Lost Island, Flathead County, Montana, , el.

Lake Koocanusa Cedar Island, Lincoln County, Montana, , el. Kins Island, Lincoln County, Montana, , el. Murray Island, Lincoln County, Montana, , el. Whites Island, Lincoln County, Montana, , el. Yarnell Island, Lincoln County, Montana, , el.

Other waters west of the divide Deer Island, Flathead County, Montana, , el. in Echo Lake Callows Island, Lincoln County, Montana, , el. in Bull Lake Firemens Island, Flathead County, Montana, , el. in Echo Lake Kelly Island, Missoula County, Montana, , el. in the Clark Fork River Pleasant Island, Flathead County, Montana, , el. in Foy Lake Rock Island, Sanders County, Montana, , el. in Noxon Reservoir Scott Island, Lincoln County, Montana, , el. in the Kootenai River Sourdough Island, Missoula County, Montana, , el. in Salmon Lake (Montana) Steamboat Island, Sanders County, Montana, , el. in the Clark Fork River The Island, Flathead County, Montana, , el. in Whitefish Lake

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