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LakeQuality

Hypereutrophic lakes (TSI above 70) are at the upper end of the productivity scale: visible algal blooms most weeks of summer, clarity often under 3 feet, and meaningful risk of harmful-algal-bloom toxin events. 124 hypereutrophic lakes are on the Minnesota books. Almost none of them are deep — 2% break 50 feet. Shallow basin plus heavy nutrient input is the consistent recipe.

Hypereutrophic lakes overwhelmingly grade D or F — the trophic class and the grade are measuring closely-related dimensions of the same underlying nutrient regime.

#LakeCountyGradeClarityDepthTSI
1Union LakeRiceD3 ft10 ft72
2Rice LakeScottD1.7 ft-77
3Scotch LakeLe SueurD2.6 ft11 ft71
4Kansas LakeWatonwanD1.5 ft7 ft71
5Yankton LakeLyonD0.8 ft8 ft70
6Gonz LakeWrightD--74
7O'Leary LakeDakotaF2.6 ft33.5 ft71
8Mud LakeHennepinF0.9 ft-78
9Mud LakeWashingtonF1.2 ft-72
10Mud LakeMartinF1.6 ft19 ft71
11Snelling LakeHennepinF1.8 ft9.5 ft71
12Long LakeDakotaF1.6 ft-72
13Unnamed LakeMeekerF0.7 ft15 ft80
14Unnamed LakeHennepinF--78
15Jonathan LakeCarverF1.6 ft-74
16Peltier LakeAnokaF2.5 ft18 ft74
17Tetonka LakeLe SueurF3 ft35 ft72
18Clear LakeMeekerF3 ft18 ft70
19Clear LakeBrownF0.8 ft8 ft78
20Clear LakeWasecaF2.5 ft34 ft70
21Clear LakeLe SueurF1.2 ft18 ft78
22Clear LakeMartinF1 ft7 ft71
23Eagle LakeCarverF2 ft14 ft73
24Fish LakeBeckerF1 ft-76
25Wheeler North LakeKandiyohiF1 ft-80
26Roberds LakeRiceF2.5 ft43 ft75
27Charlotte LakeStevensF0.9 ft20 ft79
28Emily LakeChisagoF1.6 ft-71
29Rice LakeHennepinF2.3 ft11.5 ft77
30Pokegama LakePineF2 ft25 ft71
31George LakeMartinF2 ft11 ft71
32Big Woods LakeCarverF1.5 ft-76
33Goose LakeRamseyF0.7 ft6 ft80
34Goose LakeCarverF1.2 ft10 ft77
35Goose LakeGoodhueF0.4 ft5.7 ft80
36Goose LakeHennepinF0.8 ft8 ft77
37Goose LakeWashingtonF1.5 ft-71
38Typo LakeAnokaF1 ft6 ft77
39Powderhorn LakeHennepinF1.5 ft24 ft72
40Fountain LakeWrightF1 ft10 ft78
41Crystal LakeBlue EarthF1.5 ft8 ft73
42Benton LakeCarverF1 ft-77
43Foster LakeWrightF1.6 ft10 ft75
44Knife LakeKanabecF2 ft15 ft73
45Diamond LakeHennepinF1.7 ft8 ft73
46Ardmore LakeHennepinF1.3 ft20 ft79
47Francis LakeIsantiF2 ft7 ft71
48Rebecca LakeDakotaF2.6 ft15 ft71
49Schultz LakeKandiyohiF1.3 ft-76
50Alice LakeOtter TailF0.8 ft-86
51Arvilla LakeMeekerF1 ft9 ft75
52Vadnais LakeRamseyF1 ft9 ft74
53Victoria LakeHennepinF1.2 ft-70
54Rose LakeWashingtonF1.8 ft11.3 ft72
55Circle LakeRiceF1.5 ft14 ft79
56Little Rock LakeBentonF1.8 ft17 ft74
57Hanska LakeBrownF1 ft16 ft78
58Fox LakeMartinF1 ft20 ft76
59Fox LakeMurrayF0.6 ft8.5 ft78
60Cleary LakeScottF2.3 ft9 ft72
61Hazeltine LakeCarverF1 ft-77
62Loon LakeJacksonF0.9 ft8 ft80
63Sylvan LakeHennepinF1.2 ft-78
64Cameron LakePolkF1 ft9 ft76
65Miller LakeCarverF1.6 ft14 ft76
66Mcknight LakeCarverF2.2 ft-71
67Parley LakeCarverF1.8 ft18 ft70
68Spring LakeHennepinF3.4 ft-76
69French LakeRiceF1.7 ft56 ft71
70Amber LakeMartinF2 ft19 ft70
71Swede LakeCarverF2 ft12 ft72
72Augusta LakeDakotaF0.7 ft-79
73Malmedal LakePopeF1.6 ft10 ft74
74Simon LakePopeF1.3 ft-72
75Dean LakeWrightF4.3 ft20 ft70
76Lower Orono LakeSherburneF2.5 ft18 ft71
77Unn PondDakotaF2 ft-70
78Uhlenkolts LakeStearnsF0.7 ft18 ft82
79Cottonwood LakeLyonF1.8 ft7 ft72
80Wells LakeRiceF2 ft4 ft72
81Pearl LakeJacksonF1 ft6 ft77
82Mccarthy LakeDakotaF1 ft19 ft79
83Stay LakeLincolnF1 ft6 ft74
84East Toqua LakeBig StoneF1.6 ft9 ft78
85Indian LakeNoblesF2.5 ft6 ft72
86Maria LakeCarverF0.8 ft6 ft86
87Shakopee LakeChippewaF1.5 ft-79
88Millstone LakeWrightF0.8 ft8.5 ft77
89Little Mary LakeWrightF1.5 ft-74
90Upper Sakatah LakeLe SueurF3 ft12 ft74
91Albion LakeWrightF1 ft-75
92Wilhelm LakeWrightF2 ft-71
93Split Rock ReservoirPipestoneF1.3 ft16 ft75
94Little Waverly LakeWrightF1.5 ft12 ft80
95Northwood LakeHennepinF1.5 ft-75
96Swartout LakeWrightF4.6 ft-73
97Henshaw LakeWrightF1 ft8 ft74
98Byllesby LakeDakotaF3 ft50 ft70
99Ocheda LakeNoblesF1.6 ft5 ft76
100Cowley LakeHennepinF0.8 ft-89

Source: EPA National Aquatic Resource Surveys, 2026.