Largest lakes & reservoirs in Montana by acres
There is no widely-accepted minimum surface area that defines a lake. What LakeLubbers describes as a lake, you might call a pond. Acreage of a lake (or sometimes square kilometers) is most often measured at the top surface area when the lake is at normal elevation. The surface area can be considerably smaller or larger when lake levels are lower or higher than normal. North America’s Lake Superior is the world’s largest freshwater lake by this measure.The other measure of a lake’s size is the lake’s water volume. By that measure, the world’s largest freshwater lake is Lake Baikal in Siberia.
You can find many of the world’s largest lakes (acres) on LakeLubbers in the comparison table below. Note: For some lakes, "Largest Lakes - Acres" data is unknown or does not apply, so you may see fewer lakes than the total 30 articles we have published for Montana lakes.
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Below are lakes within USA > US West Region > Montana > Compared by surface area in acres. This list does not represent all lakes in Montana, only the 30 Montana lake articles we have published on the LakeLubbers website.
Lake name | Surface area in acres | Lake description |
---|---|---|
Fort Peck Lake, MT (Missouri River Country, MT, Montana, US West Region, USA) |
245,000 ac | Fort Peck Lake, located 20 miles southeast of Glasgow, Montana on Montana Highway 24, is the 5th-largest man-made reservoir by volume in the United St… |
Flathead Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
122,560 ac | Carved out by the historic glaciers of the last ice age approximately 11,000 years ago, Flathead Lake is one of the largest natural freshwater lakes i… |
Lake Koocanusa, MT / Canada (British Columbia, Canada, Canada, Glacier Country, MT, Montana, US West Region, USA) |
46,720 ac | Also known as Koocanusa Lake, Koocanusa Reservoir In the far north of the United States, tucked into the northwestern end of Montana, is the long, narrow Lake Koocanusa. This lake is actually a man-ma… |
Canyon Ferry Lake, MT (Gold West Country, MT, Montana, US West Region, USA) |
33,500 ac | For lake lovers who relish the beauty of nature and the wonder of wildlife, there’s no better place to relax and have fun than at Canyon Ferry Lake. A… |
Hungry Horse Reservoir (Glacier Country, MT, Montana, US West Region, USA) |
23,800 ac | Hungry Horse Reservoir in Montana’s Glacier Country offers a wealth of recreational opportunities to northwestern Montana visitors. The nearly 24,000-… |
Hebgen Lake (Gold West Country, MT, Montana, US West Region, USA, Yellowstone Country, MT) |
12,564 ac | Anglers will find some of Montana’s best stillwater trout fishing at Hebgen Lake. The 12,500-acre reservoir lies conveniently just outside the western… |
Lake McDonald, MT (Glacier Country, MT, Montana, US West Region, USA) |
6,823 ac | It’s barely daylight and his family is still sleeping in their lakeside cabin on Lake McDonald. He was so eager; he couldn’t wait. Nothing breaks the… |
Saint Mary Lake (Glacier Country, MT, Montana, US West Region, USA) |
3,923 ac | Also known as St. Mary Lake, Saint Mary's Lake, St. Mary's Lake At 3900 acres, Saint Mary Lake is the second-largest lake in Glacier National Park. Saint Mary Lake is one of the most visited lakes, because the popu… |
Whitefish Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
3,315 ac | Surrounded by the Rocky Mountains, Whitefish Lake in Northwestern Montana spans 3,315 acres and is seven miles long. Created by a melted glacier, the… |
Swan Lake MT (Glacier Country, MT, Montana, US West Region, USA) |
3,269 ac | Montana conjures images of snow-capped mountains and clean waters full of fish, and Swan Lake more than lives up to that reputation. Surrounded by the… |
Ashley Lake (Glacier Country, MT, Montana, US West Region, USA) |
2,850 ac | Also known as Ashley Lake Ashley Lake is a special treat in Montana’s Glacier Country. Several miles of gravel road are required to get to the lake’s shore, so it is never over… |
Waterton Lakes (Alberta, Canada, Canada, Glacier Country, MT, Montana, US West Region, USA) |
2,496 ac | Also known as Chief Mountain Lake, Knights Lake, Kootenay Lakes “Where the mountains meet the prairies” is the motto of Waterton Lakes National Park, the home of three Waterton Lakes that straddle the Montana-Alber… |