Largest lakes & reservoirs in Montana by shoreline length
The length of the exterior shoreline around a lake is measured at the lake’s normal elevation. The shoreline length can be considerably shorter or longer when lake water levels are lower or higher than normal. A lake with many coves has a much longer shoreline than a lake of similar surface area that is nearly circular in shape.When known, the shoreline miles that we report in our statistics include only the lake’s exterior shoreline, and exclude the shorelines of islands located within a lake’s boundaries. In lakes with many islands, those islands’ combined shorelines may exceed a lake’s exterior shoreline.
You can find many of the world’s longest-shoreline lakes on LakeLubbers. Note: For some lakes, "Longest Shorelines" data is unknown or does not apply, so this table may display 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 longest shoreline length in miles. This list does not represent all lakes in Montana, only the 30 Montana lake articles we have published on the LakeLubbers website.
Lake name  |
Shoreline length in miles |
Lake description |
|---|---|---|
| Fort Peck Lake, MT (Missouri River Country, MT, Montana, US West Region, USA) |
1,520 mi | 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… |
| Lake Koocanusa, MT / Canada (British Columbia, Canada, Canada, Glacier Country, MT, Montana, US West Region, USA) |
249 mi | 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… |
| Hungry Horse Reservoir (Glacier Country, MT, Montana, US West Region, USA) |
170 mi | Hungry Horse Reservoir in Montana’s Glacier Country offers a wealth of recreational opportunities to northwestern Montana visitors. The nearly 24,000-… |
| Flathead Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
161 mi | 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… |
| Canyon Ferry Lake, MT (Gold West Country, MT, Montana, US West Region, USA) |
76 mi | 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… |
| Hebgen Lake (Gold West Country, MT, Montana, US West Region, USA, Yellowstone Country, MT) |
70 mi | 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… |
| Saint Mary Lake (Glacier Country, MT, Montana, US West Region, USA) |
23 mi | 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… |
| Waterton Lakes (Alberta, Canada, Canada, Glacier Country, MT, Montana, US West Region, USA) |
18 mi | 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… |
| Whitefish Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
16 mi | 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… |
| Echo Lake MT (Glacier Country, MT, Montana, US West Region, USA) |
16 mi | Tiny islands, curving coves and wide bays are part of the allure of northern Montana’s Echo Lake. Coupled with mountains, wildlife, and the smell of t… |
| Bowman Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
14 mi | Bowman Lake is located in the northwest corner of scenic Waterton-Glacier International Peace Park. The crystal clear waters of Bowman Lake reflect th… |
| Ashley Lake (Glacier Country, MT, Montana, US West Region, USA) |
14 mi | 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… |