What is the cleanest lake in Oklahoma?

Lake Texoma in Grayson County is the highest-rated lake in Oklahoma with an EPA water quality grade of C and 4.2 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 Oklahoma

Lake Texoma in Grayson County leads the rankings with a water quality grade of C and 4.2 ft of clarity. Below are the top 6 cleanest monitored lakes in Oklahoma, ranked by EPA water quality score.

Ranked List

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Lake Texoma	Grayson	C	4.2 ft	36 µg/L	13 µg/L
2	Grand Lake	Delaware	D	1.6 ft	720 µg/L	-
3	Wes Watkins Reservoir	Pottawatomie	D	1.8 ft	32 µg/L	18.2 µg/L
4	Lake Nahni Waiya Tuskahomma	Pushmataha	D	-	250 µg/L	-
5	Lake Sardis Clayton	Pushmataha	D	-	260 µg/L	-
6	Lake Hugo Hugo	Choctaw	D	-	430 µg/L	-

Ranked List

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