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LakeQuality

Most well-managed working lakes register as mesotrophic — the band that balances productivity with clarity. 27 lakes in Colorado 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 sit in the middle of the phosphorus and chlorophyll-a range: productive but still clear, with readings that rarely reach the EPA's poorest condition class.

#LakeCountyClarityDepthTSI
1Pueblo ReservoirPueblo6.5 ft-47
2Lon Hagler ReservoirLarimer4.6 ft-49
3Boyd LakeLarimer4.6 ft-50
4Crystal ReservoirMontrose15.4 ft-40
5Douglas ReservoirLarimer4.1 ft-45
6Highline LakeMesa3 ft-53
7Elkhead ReservoirMoffat5.2 ft-48
8Chambers LakeLarimer5.1 ft-46
9Lake Granby Dam BottomGrand--41
10Willow Creek ReservoirGrand3.9 ft-54
11Grand LakeGrand8.7 ft-43
12Skaguay ReservoirTeller12.5 ft-41
13Sweitzer ReservoirDelta3.6 ft-54
14Crawford ReservoirDelta5.6 ft-54
15Ridgway ReservoirOuray9.8 ft-47
16The Loch Hypolimnion LakeLarimer--41
17The Loch Surface LakeLarimer--43
18Shadow Mountain LakeGrand7.9 ft-47
19Blue Mesa ReservoirGunnison11.5 ft-47
20Dillon ReservoirSummit11.6 ft-47
21Dowdy LakeLarimer8.2 ft-45
22Elevenmile ReservoirPark13.1 ft-47
23Haviland LakeLa Plata13.8 ft-43
24Turquoise ReservoirLake16.1 ft-45
25Steamboat LakeRoutt6.6 ft-48
26Windy Gap ReservoirGrand--51
27Sky Pond HypolimnionLarimer--44

Source: EPA National Aquatic Resource Surveys, 2026.