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LakeQuality

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. 19 Oklahoma lakes register as eutrophic. Only 0% are deep — eutrophy correlates with shallowness, agricultural watersheds, and the kind of nutrient-input history that takes decades to shift.

Eutrophic lakes typically carry higher phosphorus and chlorophyll-a readings. The same nutrient richness that defines the trophic class shows up in those numbers.

#LakeCountyClarityDepthTSI
1Lake TexomaGrayson4.2 ft-56
2Sarge Creek LakeKay--69
3Lake TexomaMarshall1.7 ft-69
4Lake ThunderbirdCleveland1.7 ft-65
5Greenleaf LakeMuskogee2.5 ft-62
6Lake KonawaSeminole3.1 ft-61
7Wes Watkins ReservoirPottawatomie1.8 ft-61
8Spavinaw LakeMayes3.3 ft-58
9Copan LakeWashington1.6 ft-69
10Eucha LakeDelaware3.1 ft-58
11Sportsman LakeSeminole6.2 ft-56
12Wewoka LakeSeminole2.5 ft-63
13Washunga Bay LakeKay--72
14Sandy Beach LakeOsage--71
15Coon Creek LakeKay--75
16Osage Cove LakeOsage--70
17Pioneer Cover LakeOsage--70
18Thunderbird Lake Hog CreekCleveland--57
19Thunderbird Lake Fisherman'SCleveland--57

Source: EPA National Aquatic Resource Surveys, 2026.