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LakeQuality
Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water

Jefferson County Lake Quality

Oregon, 22 lakes, measured by Oregon DEQ

The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. 6 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. Phosphorus and algae readings vary widely across Jefferson County; the per-lake pages below carry the numbers.

The county's lakes lean shallow, which makes the readings sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest measured lake is Billy Chinook Reservoir.

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Quick Answers for Jefferson County

Cleanest lakes in Jefferson County →Cleanest lakes in Oregon →Best swimming lakes in Oregon →

Planning a trip? Check special fishing regulations for Billy Chinook Reservoir — or check the official Oregon fishing regulations.

All Lakes in Jefferson County

22 lakes · 6 ranked on readings, 16 without enough sampling6 lakes ranked on readings · 16 without enough sampling, hidden

#LakeClarityPhosphorusAlgaeTrophicMax DepthAccess
1Billy Chinook ReservoirJefferson4.4 ft70 µg/L2.2 µg/LNo recent samplesNo recent samplesNot recorded
2Deschutes River Arm LakeJefferson4.6 ft60 µg/L4.4 µg/LNo recent samplesNo recent samplesNot recorded
3Round Butte Dam Forebay LakeJefferson5.6 ft40 µg/L4.6 µg/LNo recent samplesNo recent samplesNot recorded
4Crooked River Arm LakeJeffersonNo recent samples60 µg/L24.6 µg/LNo recent samplesNo recent samplesNot recorded
5Lake Billy Chinook Deschutes R Arm @ Floating StationJeffersonNo recent samples35 µg/L27.7 µg/LNo recent samplesNo recent samplesNot recorded
6Haystack Reservoir Campground Boat RampJeffersonNo recent samplesNo recent samples15.7 µg/LNo recent samplesNo recent samples✓ Public
Cabot Lake Along Se SideJeffersonNo recent samples20 µg/LNo recent samplesNo recent samplesNo recent samplesNot recorded
Currant Creek ReservoirJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Pelton Regulating ReservoirJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Lake SimtustusJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Boulder LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Trout LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Island LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Long LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Monon LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Harvey LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Olallie LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samples40 ft✓ Public
Suttle LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samples70 ft✓ Public
Blue LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samples315 ftNot recorded
Square LakeJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Brewer ReservoirJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded
Little Willow Creek ReservoirJeffersonNo recent samplesNo recent samplesNo recent samplesNo recent samplesNo recent samplesNot recorded

NR = no nutrient or algae reading on record. The measurements are published as the authority reports them. Where the data comes from.

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Other Counties in Oregon

Wallowa County

13 lakes

Clackamas County

10 lakes

Washington County

3 lakes

Marion County

14 lakes

Linn County

22 lakes

Lane County

41 lakes

Browse every Oregon lake, or the full directory of lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..

Source: the Oregon Department of Environmental Quality. See data sources.