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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. 25 Utah 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 Powell Goodhope Bay MidchannelGarfield6.1 ft-51
2Beaver Meadow ReservoirSummit4.6 ft-50
3Newcastle ReservoirIron9.5 ft-60
4Willard Bay ReservoirBox Elder2.3 ft-59
5Gunnison ReservoirSanpete0.8 ft-68
6Bear R Bay Outflow LakeWeber--67
7Gsl Farmington Bay Outflow LakeDavis1 ft-78
8Lower Bowns ReservoirGarfield9.2 ft-51
9Cutler ReservoirCache1.2 ft-68
10Big East LakeUtah7.7 ft-53
11Johnson ReservoirSevier2 ft-66
12Mill Meadow ReservoirWayne5.9 ft-59
13Scofield ReservoirCarbon12.5 ft-48
14Piute ReservoirPiute1 ft-62
15Redmond LakeSevier0.7 ft-70
16Otter Creek ReservoirPiute5.2 ft-54
17Whitney ReservoirSummit17.7 ft-45
18Woodruff Creek ReservoirRich11.5 ft-50
19Baker Dam ReservoirWashington3.6 ft-63
20Hoop LakeSummit5.6 ft-56
21Panguitch L Shore LakeGarfield5.7 ft-61
22Matt Warner Reservoir EUintah6.2 ft-58
23Birch Creek ReservoirRich7.4 ft-54
24Willard Pond West EndBox Elder4.3 ft-65
25Willard Pond East EndBox Elder6.4 ft-62

Source: EPA National Aquatic Resource Surveys, 2026.