What is the cleanest lake in Tennessee?

Piney River Lake in Rhea County is the highest-rated lake in Tennessee with an EPA water quality grade of B and 6.4 feet of water clarity.

How are these rankings calculated?

Lakes are graded A through F on nutrients and algae — total phosphorus, nitrogen, chlorophyll-a, and turbidity — against EPA National Lakes Assessment 2022 condition classes for that lake’s ecoregion. Water clarity (Secchi depth) is measured and shown; it is not the letter. Lakes without enough recent samples are UNRATED, not given an F. Source data comes from the EPA Water Quality Portal.

Cleanest Lakes in Tennessee

Piney River Lake in Rhea County leads the rankings with a water quality grade of B and 6.4 ft of clarity. Below are the top 17 cleanest monitored lakes in Tennessee, ranked by EPA water quality score.

Ranked List

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Piney River Lake	Rhea	B	6.4 ft	18 µg/L	-
2	Hiwassee River Lake	Bradley	C	4.1 ft	29.3 µg/L	-
3	Tennessee River Lake	Rhea	C	7.1 ft	29.1 µg/L	-
4	Tennessee River Lake	Knox	C	-	33 µg/L	-
5	Tennessee River Lake	Roane	C	-	28.6 µg/L	-
6	Tennessee River Lake	Marion	D	7.6 ft	35.4 µg/L	-
7	Tennessee River Lake	Henry	D	-	56.5 µg/L	-
8	Ocoee River Lake	Polk	D	7.5 ft	50 µg/L	-
9	Clinch River Lake	Roane	D	-	36 µg/L	-
10	Cumberland River Lake	Davidson	D	-	69.4 µg/L	-
11	Cumberland River Lake	Wilson	D	-	35 µg/L	-
12	Big Sandy River Lake	Benton	D	-	64 µg/L	-
13	Beech River Lake	Decatur	D	-	96 µg/L	-
14	Duck River Lake	Humphreys	D	-	200 µg/L	-
15	Robertson Creek Lake	Hawkins	D	-	48.3 µg/L	-
16	Mckellar Lake	Shelby	D	-	76 µg/L	-
17	Watauga River Lake	Washington	D	-	36.8 µg/L	-

Ranked List

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