Deep Lakes in Minnesota & Wisconsin
Lakes over 50 feet deep in Minnesota and Wisconsin. Deep lakes hold cold, oxygenated water below the thermocline, supporting lake trout and cisco.
Maximum-depth data currently comes from the Minnesota and Wisconsin DNR lake surveys, so these rankings cover MN and WI lakes only. Clarity and nutrient readings for lakes in every other covered state are on each lake page.
- 50+ ft maximum depth
| Rank | Lake | County | State | Depth | Area | Fish |
|---|---|---|---|---|---|---|
| 1 | Gilbert Pit Lake | St. Louis | MN | 443 ft | 243 acres | 10 |
| 2 | St James Pit Lake | St. Louis | MN | 381 ft | 124 acres | 5 |
| 3 | Priest Lake | Bonner | ID | 369 ft | 23,426 acres | 0 |
| 4 | Wazee Lake | Jackson | WI | 350 ft | 146 acres | 0 |
| 5 | Watauga Lake | Carter | TN | 265 ft | 6,353 acres | 0 |
| 6 | Iron Chief Complex Lake | St. Louis | MN | 262.1 ft | 207 acres | 3 |
Frequently Asked Questions
Why are deep lakes important for water quality?
Deep lakes maintain a thermocline (temperature barrier) that keeps bottom water cold and oxygen-rich throughout summer. This supports coldwater fish species like lake trout and cisco that cannot survive in shallower, warmer lakes. Deep lakes also resist algae blooms better because their large volume dilutes nutrients.
What is the deepest lake in Minnesota and Wisconsin?
The deepest lakes in both states exceed 200 feet. These deep lakes are typically located in geologically carved basins from glacial activity and offer some of the best water quality and coldwater fishing in the region.
Source: EPA National Aquatic Resource Surveys, 2026.