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LakeQuality

A eutrophic lake is a productive ecosystem with the trade-offs that come with productivity: more food at the base of the food web, more clarity reduction by mid-summer, more dissolved-oxygen variability near the bottom. 14 Oregon 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
1Bully Creek LakeMalheur4.9 ft-62
2Lava LakeDeschutes17.6 ft-47
3Davis LakeDeschutes--57
4Crooked River Arm LakeJefferson--63
5Lake Billy Chinook Deschutes R Arm @ Floating StationJefferson--59
6Prineville ReservoirCrook--50
7Devil'S LakeLincoln--58
8Fish LakeJackson--51
9Howard Prairie LakeJackson--53
10Unity ReservoirBaker--59
11Phillps LakeBaker--53
12Lake OwyheeMalheur--57
13Ochoco Lake County Park Boat RampCrook--55
14Haystack Reservoir Campground Boat RampJefferson--58

Source: EPA National Aquatic Resource Surveys, 2026.