Fossil Lake, Montana
133 acres
Surface Area
About 140 ft
Max Depth (Approximate)
9,895.76 ft
Surface Elevation
Where It Sits, and How Deep It Goes
Locator - Montana
45.09 degrees N, 109.79 degrees W - Carbon County. State and county outlines drawn from Census boundary data; the lake marker is placed by its Montana Fish, Wildlife & Parks coordinates, not by eye. Schematic - not a survey map.
Depth Profile - Fossil Lake
Schematic cross-section drawn to one shared depth scale - not a survey or bathymetric map. Max depth is approximate, from state bathymetry.
How Fossil Lake Stacks Up
- About 73 miles from Bozeman, as the crow flies.
- 1 fish species on the FWP list for this lake.
Fish Species
Yellowstone Cutthroat Trout
Species recorded for this lake. Presence only - no abundance ratings.
Facts and Figures
Waterbody ID55322091
CountyCarbon
Coordinates45.0915, -109.7893
Largest Lakes in Montana
| # | Lake | County | Surface Area | Max Depth |
|---|---|---|---|---|
| 1 | Fort Peck Lake | Valley | 233,053 acres | - |
| 2 | Flathead Lake | Lake | 122,132 acres | About 380 ft |
| 3 | Canyon Ferry Lake | Broadwater | 32,773 acres | About 170 ft |
| 4 | Lake Koocanusa | Lincoln | 28,723 acres | - |
| 5 | Hungry Horse Reservoir | Flathead | 23,577 acres | - |
Sources: Montana Fish, Wildlife & Parks lake data (ID 55322091); Washington Dept. of Ecology bathymetry (approximate max depth). Verified October 30, 2026.