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LakeQuality

Mesotrophic Lakes in Ontario

1051 mesotrophic lakes in Ontario. Moderate nutrients, good water quality.

Most well-managed working lakes register as mesotrophic — the band that balances productivity with clarity. 1,051 lakes in Ontario sit in the mesotrophic band. About 0% are deep (50+ ft); the rest are shallower basins where watershed management keeps nutrients from pushing the system into eutrophy.

Mesotrophic lakes tend to grade B or C on the LakeGrade rubric — the productive-but-clear band lines up with the middle of the letter grades.

#LakeCountyGradeClarityDepthTSI
1Athelstane LakeThunder Bay DistrictA--40
2Batwing LakeThunder Bay DistrictA--42
3Bobs LakeCochrane DistrictA--42
4Burr LakeParry Sound DistrictA--47
5Cedar LakeKenora DistrictA--47
6Cranberry LakeParry Sound DistrictA--46
7Hawkeye LakeThunder Bay DistrictA--41
8Hoof LakeThunder Bay DistrictA--44
9Katchewanooka LakePeterboroughA16.4 ft-41
10Lower Fry LakeParry Sound DistrictA--40
11Mcfadden LakeHaliburtonA--41
12Niobe LakeRainy River DistrictA--41
13Perrault LakeKenora DistrictA--46
14Porcupine LakeCochrane DistrictA--42
15Prelate LakeThunder Bay DistrictA--43
16Sheldrake LakeLennox and AddingtonA--44
17St Therese LakeCochrane DistrictA--45
18Sunday LakeThunder Bay DistrictA--42
19Taggart LakeNipissing DistrictA--43
20Cade LakeLennox and AddingtonA--46
21Cedar LakeHaliburtonA--41
22Darling LakeFrontenacA--41
23Fawn LakeParry Sound DistrictA--41
24Fish LakeParry Sound DistrictA--42
25Ham LakeSudbury DistrictA--44
26Haynes LakeYork RegionA--41
27Horseshoe LakeSudbury DistrictA--46
28Island LakeDufferinA--43
29Mann LakeLanarkA--44
30Marion LakeMuskoka DistrictA--42
31Mcknight LakeHastingsA--41
32Mill PondLeeds and Grenville CountiesA--45
33Ottermere LakeKenora DistrictA--47
34Ragged LakeHastingsA--46
35Spring LakeFrontenacA--40
36St George LakeSimcoeA--45
37Stranger LakeKenora DistrictA--40
38Swan LakeTimiskaming DistrictA--46
39Thorne LakeMuskoka DistrictA--41
40Vixen LakePeterboroughA--40
41Whalley LakeParry Sound DistrictA--41
42Airport LakeKenora DistrictA--44
43Black LakeFrontenacA--44
44Black LakeKenora DistrictA--45
45Britchless LakeRenfrewA--41
46Charland LakeCochrane DistrictA--44
47Clear LakeRenfrewA--40
48Clearwater LakeMuskoka DistrictA--43
49Constant LakeRenfrewA--44
50Devine LakeMuskoka DistrictA--44
51Dogtooth LakeKenora DistrictA--45
52Dora LakeCochrane DistrictA--46
53Duhaime LakeNipissing DistrictA--41
54Dundonald LakeCochrane DistrictA--44
55East Dundonald LakeCochrane DistrictA--45
56Edward LakeKenora DistrictA--47
57Esther LakeKenora DistrictA--46
58Flint LakeKenora DistrictA--43
59Fraser LakeHastingsA--46
60Fushimi LakeCochrane DistrictA--46
61Garson LakeSudbury DistrictA--41
62Grassy LakeSudbury DistrictA--43
63Grimsthorpe LakeRenfrewA--42
64Groundhog LakeSudbury DistrictA--41
65Gullwing LakeMuskoka DistrictA--41
66Halfway LakeMuskoka DistrictA--40
67Hanlan LakeCochrane DistrictA--44
68Heron LakeAlgoma DistrictA--42
69Howard LakeTimiskaming DistrictA--41
70Hurdman LakeNipissing DistrictA--42
71Kahmitiwajewunk LakeKenora DistrictA--45
72Kangas LakeNipissing DistrictA--43
73Little Galipo LakeHaliburtonA--46
74Little North River LakeNipissing DistrictA--40
75Little Pickerel LakeUnorganized Division No. 1A--42
76Mac LakeKenora DistrictA--41
77Maki LakeNipissing DistrictA--45
78Milton LakeThunder Bay DistrictA--45
79Noted LakeCochrane DistrictA--46
80Otto LakeTimiskaming DistrictA--44
81Patersons LakeRenfrewA--44
82Pearl LakeCochrane DistrictA--42
83Pivabiska LakeCochrane DistrictA--47
84Red Deer LakeSudbury DistrictA--46
85Robinson LakeMuskoka DistrictA--47
86Rose LakeMuskoka DistrictA--43
87Rufus LakeAlgoma DistrictA--43
88Ryan LakeAlgoma DistrictA--44
89Scott LakesTimiskaming DistrictA--40
90Simmons LakeSudbury DistrictA--44
91Smith LakeRenfrewA--43
92St Pothier LakeSudbury DistrictA--44
93Straw LakeKenora DistrictA--42
94Sucan LakeKenora DistrictA--40
95Tee LakeRenfrewA--46
96Three Nations LakeCochrane DistrictA--46
97Unktahee LakeNipissing DistrictA--43
98Wade LakeCochrane DistrictA--41
99Whittla LakeNipissing DistrictA--44
100Whyte LakeHastingsA--44
All mesotrophic lakes →Minnesota version →Wisconsin version →Illinois version →Michigan version →Iowa version →Ohio version →Pennsylvania version →New York version →Missouri version →Indiana version →North Dakota version →South Dakota version →Florida version →Colorado version →North Carolina version →Vermont version →Texas version →Oregon version →Arkansas version →Oklahoma version →Kansas version →Nebraska version →Nevada version →Arizona version →Idaho version →Montana version →New Mexico version →Tennessee version →Alabama version →Virginia version →Kentucky version →Utah version →Washington version →Wyoming version →Georgia version →Massachusetts version →Québec version →All Ontario lakes →

Source: EPA National Aquatic Resource Surveys, 2026.