Shallow Lakes in Minnesota & Wisconsin
Lakes under 20 feet deep in Minnesota and Wisconsin, ranked by water quality. Shallow water warms fast, good for wading but prone to algae blooms.
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.
- Under 20 ft maximum depth
| Rank | Lake | County | State | Depth | Area | Fish |
|---|---|---|---|---|---|---|
| 1 | Horseshoe Lake | Cass | MN | 12 ft | 127 acres | 0 |
| 2 | Shallow Lake | Hubbard | MN | 10 ft | 284 acres | 13 |
| 3 | Norway Lake | Cass | MN | 12 ft | 515 acres | 14 |
| 4 | Crooked Lake | Lake | MN | 4 ft | 60 acres | 0 |
| 5 | Spider Lake | Chisago | MN | 9 ft | 131 acres | 7 |
| 6 | Mill Lake | Becker | MN | 10 ft | 155 acres | 14 |
Frequently Asked Questions
Are shallow lakes safe for swimming?
That is a call for the state water agency and county health department. Shallow lakes warm faster and grow algae sooner in summer, so check current advisories before swimming; the readings on each lake page show what sampling has found.
Why do shallow lakes have more algae?
Shallow lakes warm up faster and wind mixes nutrients from the bottom into the water column, fueling algae growth. Without a thermocline to trap nutrients in deep water, the entire lake becomes a growth zone for algae. This is why shallow lakes are more likely to show higher nutrient and algae readings.
Source: EPA National Aquatic Resource Surveys, 2026.