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LakeQuality
Pink and orange afterglow over the treeline on Slim Lake after sunset

Updated August 2026

The State of Tennessee's Lakes 2026

Of 67 lakes in Tennessee, 3.6% sit in EPA's favourable condition classes for nutrients and algae and 67.9% in its poorer ones. Piney River Lake is the cleanest; 22 lakes (32.8%) are on an official impaired-waters list.

Data Report

67
Monitored lakes sampled
D
Average readings
3.6%
low nutrient and algae readings
32.8%
On impaired list

Tennessee nutrient and algae readings

Cleanest lakes in Tennessee

Cleanest combined nutrient and algae readings, 2026.

  1. 1.Piney River Lake — Rhea County6.4 ft clarity · 18 µg/L P
  2. 2.Hiwassee River Lake — Bradley County4.1 ft clarity · 29 µg/L P
  3. 3.Tennessee River Lake — Rhea County7.1 ft clarity · 29 µg/L P
  4. 4.Tennessee River Lake — Knox County33 µg/L P
  5. 5.Tennessee River Lake — Roane County29 µg/L P
  6. 6.Tennessee River Lake — Marion County7.6 ft clarity · 35 µg/L P
  7. 7.Tennessee River Lake — Henry County57 µg/L P
  8. 8.Ocoee River Lake — Polk County7.5 ft clarity · 50 µg/L P
  9. 9.Clinch River Lake — Roane County36 µg/L P
  10. 10.Cumberland River Lake — Davidson County69 µg/L P

Highest measured algae

Highest measured chlorophyll-a (algae) concentration.

No qualifying lakes with sufficient data.

Trending lakes

Improving

  1. 1.Piney River Lake — Rhea County
  2. 2.Tennessee River Lake — Knox County
  3. 3.Tennessee River Lake — Roane County
  4. 4.Poor Valley Creek Lake — Hawkins County
  5. 5.Emory River Lake — Roane County
  6. 6.Ocoee River Lake — Polk County
  7. 7.Reelfoot Lake Blue Basin — Lake County
  8. 8.Mckellar Lake — Shelby County

Declining

  1. 1.Tennessee River Lake — Marion County
  2. 2.Cumberland River Lake — Wilson County
  3. 3.Cumberland River Lake — Stewart County
  4. 4.Big Sandy River Lake — Benton County
  5. 5.Calderwood Lake — Blount County
  6. 6.Stock Creek Lake — Hawkins County
  7. 7.Drakes Creek Lake — Sumner County

Impaired waters in Tennessee

22 lakes appear on the EPA/state 303(d) impaired-waters list (21 formally listed, 7 with a cleanup plan/TMDL).

PCBs · 12Mercury · 11Sediment / turbidity · 9Nutrients (phosphorus, nitrogen) · 7Oxygen depletion (low DO) · 7Pathogens (E. coli, fecal) · 6Pesticides · 5Dioxins · 4

Explore Tennessee lakes

Lake Fishing Forecast

Species activity outlook by water temperature and season

Tennessee Lake Trips

Where to stay at Tennessee's top lakes, each with its readings

Readings combine total phosphorus, total nitrogen, chlorophyll-a, and turbidity from the EPA Water Quality Portal and state agencies. See the full methodology, the national State of America’s Lakes report, or all Tennessee lakes.

Cite this report: LakeQuality, “The State of Tennessee's Lakes 2026”.