What is the cleanest lake in Wisconsin?

Geneva Lake in Walworth County is the highest-rated lake in Wisconsin with an EPA water quality grade of A and 20.2 feet of water clarity.

How are these rankings calculated?

Lakes are graded A through F using the Metropolitan Council methodology, which combines Secchi depth (water clarity), total phosphorus, and chlorophyll-a (algae) into a single score. Source data comes from the EPA Water Quality Portal.

Cleanest Lakes in Wisconsin

Geneva Lake in Walworth County leads the rankings with a water quality grade of A and 20.2 ft of clarity. Below are the top 50 cleanest monitored lakes in Wisconsin, ranked by EPA water quality score.

Ranked List

#	Lake	County	Grade	Clarity	Phosphorus	Algae
1	Geneva Lake	Walworth	A	20.2 ft	13 µg/L	-
2	Round Lake	Sawyer	A	21.1 ft	14.4 µg/L	1 µg/L
3	Round Lake	Oconto	A	16.8 ft	13.8 µg/L	-
4	Deep Lake	Adams	A	15.5 ft	13.3 µg/L	-
5	Beasley Lake	Waupaca	A	18.4 ft	15.1 µg/L	-
6	Bass Lake	Washburn	A	16 ft	12.3 µg/L	-
7	Bass Lake	Oconto	A	16.8 ft	10.7 µg/L	-
8	Clear Lake	Sawyer	A	17 ft	11.2 µg/L	-
9	Clear Lake	Polk	A	15.5 ft	13.9 µg/L	-
10	Clear Lake	Lincoln	A	18 ft	10.6 µg/L	-
11	Explosion Lake	Oconto	A	17 ft	15.7 µg/L	-
12	Sugar Camp Lake	Oneida	A	16.5 ft	10.3 µg/L	-
13	Little Spider Lake	Vilas	A	16 ft	11.5 µg/L	-
14	Rosalind Lake	Vilas	A	19.3 ft	9.9 µg/L	-
15	Lake Lucerne	Forest	A	18.5 ft	9.3 µg/L	-
16	Two Island Lake	Chippewa	A	15.3 ft	15.1 µg/L	-
17	Long Lake	Bayfield	A	16.2 ft	13.7 µg/L	-
18	Long Lake	Burnett	A	21.5 ft	11.3 µg/L	-
19	Lake Metonga	Forest	A	22 ft	14 µg/L	-
20	Anderson Lake	Vilas	A	21 ft	10.4 µg/L	-
21	Archibald Lake	Oconto	A	17.6 ft	10.6 µg/L	-
22	Carlin Lake	Vilas	A	21 ft	7.3 µg/L	-
23	Wolf Lake	Adams	A	15 ft	13.1 µg/L	-
24	Butternut Lake	Forest	A	19.5 ft	11.8 µg/L	-
25	Green Lake	Oconto	A	18.3 ft	17.9 µg/L	-
26	Stone Lake	Washburn	A	23 ft	10.8 µg/L	-
27	Paya Lake	Oconto	A	20 ft	10.5 µg/L	-
28	Papoose Lake	Vilas	A	15 ft	10.4 µg/L	-
29	Deer Lake	Polk	A	16 ft	16.9 µg/L	-
30	Boot Lake	Oconto	A	21.5 ft	11.3 µg/L	-
31	Eagle Lake	Bayfield	A	17 ft	14.3 µg/L	-
32	White Lake	Marquette	A	17 ft	10.8 µg/L	-
33	White Lake	Langlade	A	17 ft	13.5 µg/L	-
34	Upper Kaubashine Lake	Oneida	A	19 ft	12 µg/L	-
35	Squash Lake	Oneida	A	17.4 ft	9.6 µg/L	-
36	Plummer Lake	Vilas	A	18 ft	11.5 µg/L	-
37	Thunder Lake	Marinette	A	18 ft	10.3 µg/L	-
38	Shell Lake	Washburn	A	16 ft	15.2 µg/L	-
39	Star Lake	Oconto	A	17 ft	14.2 µg/L	-
40	Alva Lake	Oneida	A	19.5 ft	11.5 µg/L	-
41	Franklin Lake	Forest	A	16 ft	10.8 µg/L	-
42	Franklin Lake	Oneida	A	16.2 ft	12.3 µg/L	-
43	Cable Lake	Bayfield	A	15.5 ft	14.1 µg/L	-
44	Viola Lake	Burnett	A	17 ft	17.2 µg/L	-
45	Big Portage Lake	Vilas	A	18.5 ft	11.7 µg/L	-
46	Crystal Lake	Marquette	A	16.8 ft	11.5 µg/L	-
47	Crystal Lake	Sheboygan	A	19.9 ft	12.2 µg/L	-
48	Rinehart Lake	Portage	A	19 ft	13.8 µg/L	-
49	Perch Lake	Oneida	A	15 ft	14.5 µg/L	-
50	Perch Lake	Langlade	A	17.3 ft	13.4 µg/L	-

Cleanest Lakes in Wisconsin

Ranked List

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