Deepest lakes & reservoirs in Montana by maximum depth (ft)
The estimated greatest depth of the water in a lake can be measured at the lake’s normal elevation. If the water volume and surface area of a lake are known, an estimate of the lake’s average depth can be calculated:Water volume ÷ Surface Area = Average Depth
Example: 1,000,000 acre-feet ÷ 20,000 acres = 50 feet average depth.
You can find many of the the world’s deepest lakes on LakeLubbers. If you sort the list, you will find the (maximum depth of) the shallowest lakes in our database. Note: For some lakes, lake depth data is unknown, 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 maximum depth in feet. This list does not represent all lakes in Montana, only the 30 Montana lake articles we have published on the LakeLubbers website.
Lake name  |
Max depth in feet |
Lake description |
|---|---|---|
| Tally Lake (Glacier Country, MT, Montana, US West Region, USA) |
492 ft | Also known as Talley Lake Tally Lake, in Montana’s Glacier Country region, is fast becoming a favorite among the adventurous. Located 15 miles west of the town of Whitefish, th … |
| Hungry Horse Reservoir (Glacier Country, MT, Montana, US West Region, USA) |
490 ft | Hungry Horse Reservoir in Montana’s Glacier Country offers a wealth of recreational opportunities to northwestern Montana visitors. The nearly 24,000- … |
| Waterton Lakes (Alberta, Canada, Canada, Glacier Country, MT, Montana, US West Region, USA) |
487 ft | 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 … |
| Lake McDonald, MT (Glacier Country, MT, Montana, US West Region, USA) |
472 ft | 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 … |
| Flathead Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
371 ft | 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) |
370 ft | 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 … |
| Saint Mary Lake (Glacier Country, MT, Montana, US West Region, USA) |
300 ft | 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 … |
| Bowman Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
253 ft | Bowman Lake is located in the northwest corner of scenic Waterton-Glacier International Peace Park. The crystal clear waters of Bowman Lake reflect th … |
| Whitefish Lake, MT (Glacier Country, MT, Montana, US West Region, USA) |
232 ft | 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 … |
| Fort Peck Lake, MT (Missouri River Country, MT, Montana, US West Region, USA) |
220 ft | 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 … |
| Ashley Lake (Glacier Country, MT, Montana, US West Region, USA) |
215 ft | 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 … |
| McGregor Lake (Glacier Country, MT, Montana, US West Region, USA) |
205 ft | Clear, deep McGregor Lake shines in northwestern Montana’s Glacier Country. Set against the backdrop of the Flathead National Forest and the Flathead … |