Eutrophic Lakes Across 38 States
High nutrients, frequent algae, reduced clarity. 100 lakes (20% 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. 100 the 49 states and 2 Canadian provinces LakeQuality covers lakes register as eutrophic. Only 11% 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 our A–F scale. The same nutrient richness that defines the trophic class drives the lower grade.
| Lake | County | State | Grade | Clarity | Depth |
|---|---|---|---|---|---|
| South Sturgeon Lake | St. Louis | MN | A | 2.5 ft | 43 ft |
| Schram Lake | Beltrami | MN | A | 3.9 ft | - |
| Colby Lake | St. Louis | MN | A | 3 ft | 30 ft |
| Jessie Lake | Beltrami | MN | A | 4.6 ft | 35 ft |
| East Twin Lake | St. Louis | MN | A | 2.8 ft | - |
| Howard Lake | Anoka | MN | A | 3.3 ft | - |
| Elbow Lake | Cook | MN | A | 3.7 ft | 9 ft |
| Lost Lake | Hennepin | MN | A | 3.2 ft | 6 ft |
| Sabin Lake | St. Louis | MN | A | 2.1 ft | 52 ft |
| Nichols Lake | St. Louis | MN | A | 5.1 ft | 31 ft |
| Isabella Lake | Lake | MN | A | 4.4 ft | 19 ft |
| Grass Lake | Anoka | MN | A | 4.3 ft | - |
| Silver Island Lake | Lake | MN | A | 4.4 ft | 16 ft |
| Gaslyn Lake | Burnett | WI | A | 4.5 ft | 12 ft |
| Lake St Croix | Pierce | MN | B | 7.2 ft | 78 ft |
| Third Crow Wing Lake | Hubbard | MN | B | 2.5 ft | 35 ft |
| Badger Lake | Polk | MN | B | 6.6 ft | 19 ft |
| Sarah Lake | Polk | MN | B | 7.7 ft | 27 ft |
| Pool | Washington | MN | B | 5.9 ft | 78 ft |
| Shoepack Lake | St. Louis | MN | B | 4.6 ft | 24 ft |
| Kittleson Lake | Polk | MN | B | 7.1 ft | - |
| O'Connors Lake | Washington | MN | B | 6.6 ft | - |
| Potter Lake | Walworth | WI | B | 4.3 ft | 26 ft |
| Lake St Croix | St. Croix | WI | B | 5.6 ft | 60 ft |
| Boulder Lake | Vilas | WI | B | 5.6 ft | 23 ft |
| Pickerel Lake | Vilas | WI | B | 6 ft | 26 ft |
| Round Lake | Oneida | WI | B | 4.4 ft | 15 ft |
| Rice Lake | Iron | WI | B | 5 ft | 21 ft |
| Long Lake | Shawano | WI | B | 6 ft | 35 ft |
| Nelson Lake | Sawyer | WI | B | 5 ft | - |
| Rush Lake | Vilas | WI | B | 5 ft | 7 ft |
| Rush Lake | Winnebago | WI | B | 3.2 ft | 5 ft |
| North Lake | Barron | WI | B | 5.5 ft | 21 ft |
| Crescent Lake | Polk | WI | B | 4.5 ft | 43 ft |
| Red Cedar Lake | Jefferson | WI | B | 4 ft | 6 ft |
| Wolf Lake | Fond du Lac | WI | B | 5 ft | 47 ft |
| Bark Lake | Washington | WI | B | 5.5 ft | 34 ft |
| Mud Lake | Polk | WI | B | 4.3 ft | 15 ft |
| Loon Lake | Shawano | WI | B | 5.5 ft | 22 ft |
| Big Arbor Vitae Lake | Vilas | WI | B | 6 ft | 41 ft |
| Bearskin Lake | Oneida | WI | B | 6 ft | 26 ft |
| White Lake | Waupaca | WI | B | 5.6 ft | 10 ft |
| Hartlaub Lake | Manitowoc | WI | B | 5 ft | 60 ft |
| Lake Esadore | Taylor | WI | B | 4.5 ft | 36 ft |
| Amnicon Lake | Douglas | WI | B | 5 ft | 31 ft |
| Eagle Spring Lake | Waukesha | WI | B | 4.5 ft | 8 ft |
| Ward Lake | Polk | WI | B | 6 ft | 43 ft |
| Druid Lake | Washington | WI | B | 5.5 ft | 53 ft |
| Whitewater Lake | Walworth | WI | B | 4 ft | 35 ft |
| Big Dardis Lake | Price | WI | B | 5.5 ft | - |
| Lake Waubesa | Dane | WI | B | 3.2 ft | 38 ft |
| School Section Lake | Waukesha | WI | B | 6.2 ft | 8 ft |
| School Section Lake | Waupaca | WI | B | 6.5 ft | 38 ft |
| Friess Lake | Washington | WI | B | 4 ft | 48 ft |
| Wood Lake | Burnett | WI | B | 5.5 ft | 35 ft |
| Horseshoe Lake | Manitowoc | WI | B | 6.5 ft | 54 ft |
| Deep Hole Lake | Oneida | WI | B | 4.3 ft | - |
| East Twin Lake | Marquette | WI | B | 3.3 ft | 8 ft |
| Random Lake | Sheboygan | WI | B | 4.5 ft | 22.2 ft |
| Big Stone Lake | Oneida | WI | B | 4.2 ft | 57 ft |
| Blue Spring Lake | Jefferson | WI | B | 6.2 ft | 27 ft |
| Lake Sherwood | Adams | WI | B | 5.5 ft | 27 ft |
| George Lake | Oneida | WI | B | 5 ft | 26 ft |
| Spur Lake | Oneida | WI | B | 2 ft | 3 ft |
| Hiawatha Lake | Vilas | WI | B | 4 ft | 58 ft |
| Lake Thompson | Oneida | WI | B | 4 ft | 30 ft |
| Shoe Lake | Manitowoc | WI | B | 7 ft | 34 ft |
| Clarey Lake | Polk | WI | B | 4.3 ft | 49 ft |
| Van Zile Lake | Forest | WI | B | 5.4 ft | 17 ft |
| Black Hawk Lake | Iowa | WI | B | 5 ft | 42 ft |
| Granite Lake at | Barron | WI | B | 6 ft | 34 ft |
| Tichigan Lake | Racine | WI | B | 5.5 ft | 63 ft |
| Quarry Lake | Brown | WI | B | 8 ft | - |
| Unnamed Lake | Polk | WI | B | 5 ft | - |
| Red Bass Lake | Vilas | WI | B | 3.4 ft | 22 ft |
| Lake Wingra | Dane | WI | B | 4 ft | 14 ft |
| Bakkens Pond | Sauk | WI | B | 2.5 ft | - |
| Arkdale Lake | Adams | WI | B | 5 ft | 10.5 ft |
| Patrick Lake | Adams | WI | B | 5 ft | 21 ft |
| Oneida Lake | Oneida | WI | B | 5.5 ft | 34 ft |
| Dunes Lake | Door | WI | B | 4 ft | 1 ft |
| Kaine Lake | Forest | WI | B | 3.2 ft | - |
| Delavan Lake | Walworth | WI | B | - | 52 ft |
| Axehead Lake | Cook | IL | B | 11.9 ft | - |
| Boulder South Lake | Perry | IL | B | 8.8 ft | - |
| Wampum Lake | Cook | IL | B | 6.9 ft | - |
| Shabbona Lake | DeKalb | IL | B | 4.9 ft | - |
| Big Rock Lake | Kane | IL | B | 8.1 ft | - |
| Round Lake | Lake | IL | B | 7.4 ft | - |
| Channel Lake | Lake | IL | B | 8 ft | - |
| Zurich Lake | Lake | IL | B | - | - |
| West Loon Lake | Lake | IL | B | - | - |
| Barton Lake West Basin; Schoolcraft Township | Kalamazoo | MI | B | 8 ft | - |
| Posey Lake Central Basin; Hudson Township | Lenawee | MI | B | 5 ft | - |
| Little Africa Lake; Central Basin; Watersmeet Township | Gogebic | MI | B | 4 ft | - |
| Spectacle Lake | Chippewa | MI | B | - | - |
| North Pond | Chippewa | MI | B | - | - |
| Storm Lake Max Depth | Buena Vista | IA | B | 1.7 ft | - |
| Arrowhead Lake | Sac | IA | B | 5.6 ft | - |
| Kent Park Lake | Johnson | IA | B | 4.8 ft | - |
Eutrophic Lakes by State
Frequently Asked Questions
What is an eutrophic lake?
High nutrients, frequent algae, reduced clarity. There are 100 eutrophic lakes across the 49 states and 2 Canadian provinces LakeQuality covers, representing 20% 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.