Mesotrophic Lakes in Oregon
15 mesotrophic lakes in Oregon. Moderate nutrients, good water quality.
Mesotrophic lakes are the productive middle of the trophic scale — TSI between 40 and 50. Clear enough to be inviting, productive enough to support a strong fishery, with moderate phosphorus and a modest algal community that does not dominate the optical signal. 15 lakes in Oregon 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 our A–F scale — the productive-but-clear band lines up with the middle of the letter grades.
| # | Lake | County | Grade | Clarity | Depth | TSI |
|---|---|---|---|---|---|---|
| 1 | Detroit Lake | Marion | B | - | - | 43 |
| 2 | Billy Chinook Reservoir | Jefferson | C | 4.4 ft | - | 53 |
| 3 | Wickiup Reservoir | Deschutes | C | 11.2 ft | - | 45 |
| 4 | Lost Creek Lake | Jackson | C | - | - | 40 |
| 5 | Willow Lake | Jackson | C | - | - | 38 |
| 6 | Emigrant Lake | Jackson | C | - | - | 42 |
| 7 | Foster Lake | Linn | C | - | - | 39 |
| 8 | East Lake Hot Springs Boat Ramp | Deschutes | C | - | - | 41 |
| 9 | Deschutes River Arm Lake | Jefferson | D | 4.6 ft | - | 54 |
| 10 | Round Butte Dam Forebay Lake | Jefferson | D | 5.6 ft | - | 52 |
| 11 | Crane Prairie Reservoir | Deschutes | D | 8.4 ft | - | 50 |
| 12 | Crane Prairie Reservoir | Deschutes | D | - | - | 53 |
| 13 | Siltcoos Lake | Lane | D | - | - | 47 |
| 14 | Pine Hollow Reservoir | Wasco | D | - | - | 45 |
| 15 | Lemolo Lake | Douglas | D | - | - | 49 |
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 →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 →Ontario version →Québec version →Nova Scotia version →British Columbia version →Newfoundland and Labrador version →All Oregon lakes →
Source: EPA National Aquatic Resource Surveys, 2026.