Eutrophic Lakes in Minnesota & Wisconsin
High nutrients, frequent algae, reduced clarity. 952 lakes (25% of all graded lakes).
Eutrophic lakes — TSI 50 to 70 — are nutrient-rich and productive, with persistent summer algal communities that drive visible reductions in clarity. These conditions are not failures; they reflect a lake doing what nutrient-loaded waters do. 952 Minnesota and Wisconsin lakes register as eutrophic. Only 10% are deep — eutrophy correlates with shallowness, agricultural watersheds, and the kind of nutrient-input history that takes decades to shift.
Eutrophic lakes typically grade C or D on the LakeGrade rubric. The same nutrient richness that defines the trophic class drives the lower grade.
| Lake | County | State | Grade | Clarity | Depth |
|---|---|---|---|---|---|
| Kettle Lake | Carlton | MN | B | - | - |
| Erie Lake | Meeker | MN | B | - | 34 ft |
| Big Rice Lake | St. Louis | MN | B | - | 5 ft |
| North Lake 3 | Goodhue | MN | B | - | - |
| North White Ash Lake | Polk | WI | B | 16 ft | 9 ft |
| Boot Lake | Vilas | WI | B | - | 19 ft |
| Big Twin Lake | Waushara | WI | B | - | 13 ft |
| Unnamed Lake | Douglas | WI | B | - | 6 ft |
| Unnamed Lake | Washburn | WI | B | - | - |
| Okauchee Lake-Site No. 1-Near Okauchee | Waukesha | WI | B | - | 90 ft |
| L St Germain Lk Site K @ S. Bay Lake | Vilas | WI | B | - | 53 ft |
| Lk Superior Lake | Douglas | WI | B | - | - |
| Little Wood Lake | Burnett | WI | B | - | 23 ft |
| Delavan Lake | Walworth | WI | B | - | 52 ft |
| Dunes Lake Just Us of Outlet | Door | WI | B | - | - |
| Inlet To Dunes Lake | Door | WI | B | - | 1 ft |
| East Wetland Inlet To Lake Ree | Bayfield | WI | B | - | - |
| Indian School Lake | Sawyer | WI | B | - | 6 ft |
| Wiley Lake | Bayfield | WI | B | - | - |
| Jessie Lake | Beltrami | MN | B | 4.6 ft | 35 ft |
| South Lindstrom Lake | Chisago | MN | B | 5.2 ft | 34 ft |
| Simian Lake | St. Louis | MN | B | 4.5 ft | - |
| Chevans Lake Deep | Cook | MN | B | 1.9 ft | - |
| Big Lake | Stearns | MN | B | 6.9 ft | 42 ft |
| Unnamed Lake | Hennepin | MN | B | 4.3 ft | - |
| Lemay Lake | Dakota | MN | B | 6.9 ft | 15.5 ft |
| Big Pine Lake | Otter Tail | MN | B | 7 ft | 76 ft |
| White Iron Lake | Lake | MN | B | 4.5 ft | 47 ft |
| Arrowhead Lake | Crow Wing | MN | B | 6.9 ft | 13 ft |
| Comfort Lake | Chisago | MN | B | 7 ft | 47 ft |
| Sand Hill Lake | Polk | MN | B | 6.9 ft | 17 ft |
| Elbow Lake | Cook | MN | B | 3.7 ft | 9 ft |
| Rush Lake | Otter Tail | MN | B | 6.9 ft | 68 ft |
| Upper Twin Lake | Hubbard | MN | B | 6.9 ft | 12 ft |
| Toad Lake | Becker | MN | B | 7 ft | 29 ft |
| Badger Lake | Polk | MN | B | 6.7 ft | 19 ft |
| Sarah Lake | Polk | MN | B | 7.9 ft | 27 ft |
| Waverly Lake | Wright | MN | B | 7.4 ft | 70.5 ft |
| Shoepack Lake | St. Louis | MN | B | 4.6 ft | 24 ft |
| Kittleson Lake | Polk | MN | B | 7.1 ft | - |
| Peter Lake | Hennepin | MN | B | 9.9 ft | - |
| Magda Lake | Hennepin | MN | B | 14.1 ft | - |
| Beaver Hut Lake | Lake | MN | B | 3.4 ft | 12 ft |
| West Sturgeon Lake | Itasca | MN | B | 4.1 ft | 31 ft |
| Dahler Lake | Crow Wing | MN | B | 4.4 ft | - |
| Vermillion Lake | Cass | MN | B | 7.1 ft | 27 ft |
| Central Mystic Lake | Scott | MN | B | - | - |
| Rice Lake | Vilas | WI | B | 10.7 ft | 7 ft |
| Rice Lake | Grant | WI | B | 15.1 ft | - |
| Little St Germain Lake | Vilas | WI | B | 11.5 ft | 53 ft |
| Little Trade Lake | Burnett | WI | B | 11.5 ft | 19 ft |
| Helen Lake | Iowa | WI | B | 11.3 ft | 28 ft |
| Lake Kegonsa | Dane | WI | B | 12.3 ft | 32 ft |
| Crystal Lake | Barron | WI | B | 10.7 ft | 22 ft |
| Magnor Lake | Polk | WI | B | 11.9 ft | 26 ft |
| Apple River Flowage Lake | Polk | WI | B | 18 ft | 18 ft |
| Mirror Lake | Sauk | WI | B | 15.6 ft | - |
| Holcombe Flowage Lake | Chippewa | WI | B | 12.3 ft | - |
| Lower Turtle Lake | Barron | WI | B | 12.3 ft | 24 ft |
| Little Blake Lake | Polk | WI | B | 11.5 ft | 14 ft |
| Wagner Lake | Shawano | WI | B | 13.1 ft | 15 ft |
| Omer Lake | Polk | WI | B | 16.4 ft | - |
| Round Lake | Hennepin | MN | C | 7.4 ft | 37 ft |
| Horseshoe Lake | Chisago | MN | C | 4.6 ft | 53 ft |
| Schram Lake | Beltrami | MN | C | 3.9 ft | - |
| Green Lake | Chisago | MN | C | 6 ft | 32 ft |
| George Lake | Anoka | MN | C | 7.3 ft | 32 ft |
| Coon Lake | Anoka | MN | C | 5.6 ft | 27 ft |
| Perch Lake | Carlton | MN | C | 4.9 ft | - |
| Jensen Lake | Dakota | MN | C | 5 ft | - |
| Jaskari Lake | Carlton | MN | C | 6.4 ft | - |
| Rice Portage Lake | Carlton | MN | C | 1.3 ft | - |
| Middle Pigeon Lake | Itasca | MN | C | 7.5 ft | - |
| Fannie Lake | Isanti | MN | C | 7 ft | 33 ft |
| Teal Lake Deep | Cook | MN | C | 3.3 ft | - |
| Cut Foot Sioux Lake | Itasca | MN | C | 7.5 ft | - |
| Mud Lake | Wright | MN | C | 5.6 ft | 65 ft |
| Birch Lake | St. Louis | MN | C | 3.9 ft | 25 ft |
| Round Lake | Ramsey | MN | C | 8.2 ft | - |
| Long Lake | Meeker | MN | C | 7.5 ft | 28 ft |
| Unnamed Lake | St. Louis | MN | C | 4.8 ft | 7 ft |
| Unnamed Lake | Otter Tail | MN | C | 3.9 ft | - |
| Unnamed Lake | Brown | MN | C | 0.3 ft | - |
| Twin Lake | Ramsey | MN | C | 7.9 ft | 33 ft |
| Elms Lake | Isanti | MN | C | 6.9 ft | 26 ft |
| Blue Lake | Isanti | MN | C | 8.9 ft | 31 ft |
| Eagle Lake | Carlton | MN | C | 7 ft | 35 ft |
| Auburn Lake | Carver | MN | C | 7.2 ft | 84 ft |
| Colby Lake | St. Louis | MN | C | 3.5 ft | 30 ft |
| Johanna Lake | Ramsey | MN | C | 7.2 ft | 43 ft |
| Fish Lake | Dakota | MN | C | 6.9 ft | 33.5 ft |
| Sand Lake | Carlton | MN | C | 5 ft | 27 ft |
| Beaver Lake | Ramsey | MN | C | 7.9 ft | 11 ft |
| Battle Creek Lake | Washington | MN | C | 7.4 ft | 15.3 ft |
| Union Lake | Wright | MN | C | 5.5 ft | 35 ft |
| Island Lake | Itasca | MN | C | 8.9 ft | 35 ft |
| Portage Lake | Hubbard | MN | C | 5.7 ft | 17 ft |
| Gull Lake | Beltrami | MN | C | 5.9 ft | 23 ft |
| Koronis Lake | Stearns | MN | C | 6 ft | 132 ft |
| Silver Lake | Ramsey | MN | C | 7 ft | 18 ft |
Showing 100 of 952 eutrophic lakes.
Frequently Asked Questions
What is an eutrophic lake?
High nutrients, frequent algae, reduced clarity. There are 952 eutrophic lakes in Minnesota and Wisconsin, representing 25% of all graded lakes.
Can you swim in eutrophic lakes?
Eutrophic lakes may have algae blooms that make swimming inadvisable at times. Check for algae advisories before swimming.
Source: EPA National Aquatic Resource Surveys, 2026.