Oligotrophic Lakes in Wisconsin

260 oligotrophic lakes in Wisconsin. Low nutrients, clear water, excellent for swimming.

Oligotrophic lakes are the clear, cold, nutrient-poor end of the trophic scale. The Carlson Trophic State Index measures this as TSI below 40 — water transparent enough to see 15+ feet down, total phosphorus under 12 µg/L, chlorophyll-a barely registering. Across Wisconsin, 260 lakes register as oligotrophic — 37% of them break 50 feet of depth, which is the structural condition that underwrites the trophic class. Without depth and a low-nutrient watershed, oligotrophy is hard to sustain.

On the LakeGrade rubric, oligotrophic lakes almost always pull an A or B — the same low-nutrient conditions that produce the trophic class also produce the high grade.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Geneva Lake	Walworth	A	20.2 ft	135 ft	37
2	Big Bass Lake	Washburn	A	17.9 ft	27 ft	36
3	Deep Lake	Adams	A	15.5 ft	49 ft	39
4	Beasley Lake	Waupaca	A	18.4 ft	47 ft	39
5	Bass Lake	Washburn	A	16 ft	31 ft	39
6	Bass Lake	Oconto	A	16.8 ft	40 ft	37
7	Bass Lake	Oconto	A	-	25 ft	37
8	White Sand Lake Deep	Vilas	A	18 ft	63 ft	35
9	Sugar Camp Lake	Oneida	A	16.5 ft	-	37
10	Lake Lucerne	Forest	A	18.5 ft	73 ft	36
11	Lake Metonga	Forest	A	22 ft	79 ft	37
12	Round Lake	Sawyer	A	21.1 ft	74 ft	35
13	Round Lake	Waupaca	A	17.5 ft	67 ft	36
14	Round Lake	Oconto	A	16.8 ft	31 ft	39
15	Clear Lake	Sawyer	A	17.2 ft	32 ft	38
16	Clear Lake	Polk	A	15.5 ft	26 ft	40
17	Clear Lake	Lincoln	A	18 ft	45 ft	37
18	Clear Lake	Oneida	A	-	95 ft	38
19	Razorback Lake	Vilas	A	15.2 ft	35 ft	38
20	Little Spider Lake	Vilas	A	16 ft	23 ft	38
21	Rosalind Lake	Vilas	A	19.3 ft	-	36
22	Long Lake	Bayfield	A	16.2 ft	28 ft	39
23	Long Lake	Burnett	A	21.5 ft	41 ft	36
24	North Lake	Florence	A	15 ft	43 ft	38
25	Anderson Lake	Vilas	A	21 ft	63 ft	36
26	Carlin Lake	Vilas	A	21 ft	36 ft	33
27	Wolf Lake	Adams	A	15 ft	58 ft	39
28	Butternut Lake	Forest	A	19.5 ft	42 ft	37
29	Archibald Lake	Oconto	A	17.6 ft	50 ft	37
30	Hemlock Lake	Oneida	A	15 ft	25 ft	38
31	Samoset Lake	Bayfield	A	15 ft	40 ft	40
32	North Twin Lake	Polk	A	-	27 ft	37
33	Papoose Lake	Vilas	A	15 ft	65 ft	38
34	Island Lake	Bayfield	A	17 ft	51 ft	36
35	Loon Lake	Florence	A	16.8 ft	-	36
36	Loon Lake	Washburn	A	-	63 ft	34
37	Eagle Lake	Bayfield	A	17 ft	52 ft	39
38	Eagle Lake	Marinette	A	15 ft	30 ft	38
39	Stone Lake	Washburn	A	23 ft	49 ft	35
40	Paya Lake	Oconto	A	20 ft	40 ft	36
41	Boot Lake	Oconto	A	21.5 ft	38 ft	36
42	Upper Kaubashine Lake	Oneida	A	19 ft	56 ft	37
43	Squash Lake	Oneida	A	17.4 ft	74 ft	36
44	Thunder Lake	Marinette	A	18 ft	62 ft	37
45	White Lake	Marquette	A	17 ft	60 ft	37
46	White Lake	Oconto	A	15.7 ft	-	37
47	White Lake	Langlade	A	17 ft	42 ft	39
48	Plummer Lake	Vilas	A	18 ft	85 ft	37
49	Big Crawling Stone Deep Lake	Vilas	A	17 ft	87 ft	36
50	Alva Lake	Oneida	A	19.5 ft	43 ft	37
51	Rose Lake	Langlade	A	19.5 ft	24 ft	34
52	Ebert Lake	Portage	A	21 ft	30 ft	33
53	Star Lake	Oconto	A	17 ft	21 ft	39
54	Franklin Lake	Forest	A	16 ft	46 ft	38
55	Franklin Lake	Oneida	A	16.2 ft	25 ft	39
56	Sand Lake	Rusk	A	15.3 ft	100 ft	38
57	Sand Lake	Polk	A	20 ft	-	34
58	Cable Lake	Bayfield	A	15.5 ft	-	40
59	Big Portage Lake	Vilas	A	18.5 ft	40 ft	37
60	Crystal Lake	Marquette	A	16.8 ft	60 ft	38
61	Crystal Lake	Bayfield	A	16.2 ft	29 ft	37
62	Crystal Lake	Sheboygan	A	20 ft	-	37
63	Rinehart Lake	Portage	A	19 ft	27 ft	38
64	Perch Lake	Langlade	A	17.3 ft	21 ft	39
65	Mildred Lake	Oneida	A	18.5 ft	45 ft	37
66	White Birch Lake	Vilas	A	16 ft	27 ft	37
67	Forest Lake	Vilas	A	22.2 ft	60 ft	37
68	Fish Lake	Waushara	A	-	37 ft	38
69	Sea Lion Lake	Florence	A	21 ft	82 ft	36
70	Upper Eau Claire Lake	Bayfield	A	18.7 ft	92 ft	37
71	Half Moon Lake	Polk	A	15.3 ft	60 ft	40
72	Pearl Lake	Waushara	A	19 ft	45 ft	36
73	Sunset Lake	Vilas	A	17.5 ft	30 ft	37
74	Hasbrook Lake	Oneida	A	21 ft	50 ft	36
75	Millicent Lake	Bayfield	A	23 ft	-	32
76	Little Round Lake	Sawyer	A	17.3 ft	38 ft	37
77	Black Oak Lake	Vilas	A	28.5 ft	85 ft	33
78	Lower Eau Claire Lake	Bayfield	A	18.5 ft	41 ft	35
79	Tozer Lake	Washburn	A	16 ft	53 ft	39
80	Osprey Lake	Sawyer	A	16 ft	32 ft	38
81	Bear Paw Lake	Oconto	A	16 ft	20 ft	38
82	Mary Lake	Lincoln	A	21 ft	42 ft	33
83	Pine Lake	Waukesha	A	25 ft	85 ft	35
84	Pine Lake	Waushara	A	19.3 ft	21 ft	34
85	Moose Lake	Waukesha	A	16 ft	-	37
86	Leader Lake	Douglas	A	15.3 ft	56 ft	37
87	Blue Lake	Oneida	A	23 ft	49 ft	35
88	Presque Isle Lake	Vilas	A	18 ft	103 ft	37
89	Keyes Lake	Florence	A	21 ft	-	36
90	Katinka Lake	Vilas	A	18 ft	60 ft	35
91	Lee Lake	Oneida	A	22.5 ft	44 ft	33
92	Carlin Lake	Vilas	A	24 ft	36 ft	31
93	Dutch Hollow Lake	Sauk	A	15 ft	38 ft	40
94	Crawling Stone Lake	Vilas	A	16 ft	87 ft	37
95	Middle Kimball Lake	Washburn	A	16 ft	77 ft	39
96	Little Crawling Stone Lake	Vilas	A	15 ft	44 ft	38
97	Two Sisters Lake	Oneida	A	19.6 ft	-	36
98	Grindstone Lake	Sawyer	A	17.4 ft	60 ft	38
99	Dorothy Lake	Oneida	A	17 ft	35 ft	36
100	Hart Lake	Bayfield	A	21.5 ft	54 ft	33

All oligotrophic lakes →Minnesota version →Illinois version →Michigan version →Iowa version →Ohio version →Pennsylvania version →New York version →Missouri version →Indiana version →North Dakota version →South Dakota version →Florida version →Colorado version →North Carolina version →Vermont version →Texas version →Oregon version →Arkansas version →Oklahoma version →Kansas version →Nebraska version →Nevada version →Arizona version →Idaho version →Montana version →New Mexico version →Tennessee version →Alabama version →Virginia version →Kentucky version →Utah version →Washington version →Wyoming version →Georgia version →Massachusetts version →All Wisconsin lakes →

Source: EPA National Aquatic Resource Surveys, 2026.