Oligotrophic Lakes in Wisconsin

266 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, 266 lakes register as oligotrophic — 0% 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	-	37
2	Round Lake	Sawyer	A	21.1 ft	-	35
3	Round Lake	Waupaca	A	17.5 ft	-	36
4	Round Lake	Oconto	A	16.8 ft	-	39
5	Big Bass Lake	Washburn	A	17.9 ft	-	36
6	Deep Lake	Adams	A	15.5 ft	-	40
7	Beasley Lake	Waupaca	A	18.4 ft	-	39
8	Bass Lake	Washburn	A	16 ft	-	39
9	Bass Lake	Oconto	A	16.8 ft	-	37
10	Bass Lake	Oconto	A	-	-	37
11	Clear Lake	Sawyer	A	17 ft	-	38
12	Clear Lake	Polk	A	15.5 ft	-	40
13	Clear Lake	Lincoln	A	18 ft	-	37
14	Clear Lake	Oneida	A	-	-	38
15	Razorback Lake	Vilas	A	15.2 ft	-	38
16	White Sand Lake Deep	Vilas	A	18 ft	-	35
17	Sugar Camp Lake	Oneida	A	16.5 ft	-	37
18	Little Spider Lake	Vilas	A	16 ft	-	38
19	Rosalind Lake	Vilas	A	19.3 ft	-	36
20	Lake Lucerne	Forest	A	18.5 ft	-	36
21	Long Lake	Bayfield	A	16.2 ft	-	39
22	Long Lake	Burnett	A	21.5 ft	-	36
23	Lake Metonga	Forest	A	22 ft	-	37
24	North Lake	Florence	A	15 ft	-	38
25	Anderson Lake	Vilas	A	21 ft	-	36
26	Archibald Lake	Oconto	A	17.6 ft	-	37
27	Carlin Lake	Vilas	A	21 ft	-	33
28	Wolf Lake	Adams	A	15 ft	-	40
29	Butternut Lake	Forest	A	19.5 ft	-	37
30	Stone Lake	Washburn	A	23 ft	-	35
31	Hemlock Lake	Oneida	A	15 ft	-	38
32	Paya Lake	Oconto	A	20 ft	-	36
33	Island Lake	Bayfield	A	17 ft	-	36
34	North Twin Lake	Polk	A	-	-	37
35	Papoose Lake	Vilas	A	15 ft	-	38
36	Boot Lake	Oconto	A	21.5 ft	-	36
37	Loon Lake	Florence	A	16.8 ft	-	36
38	Loon Lake	Washburn	A	-	-	32
39	Eagle Lake	Bayfield	A	17 ft	-	39
40	Eagle Lake	Marinette	A	15 ft	-	38
41	White Lake	Marquette	A	17 ft	-	37
42	White Lake	Oconto	A	15.7 ft	-	37
43	White Lake	Langlade	A	17 ft	-	39
44	Upper Kaubashine Lake	Oneida	A	19 ft	-	37
45	Squash Lake	Oneida	A	17.4 ft	-	36
46	Plummer Lake	Vilas	A	18 ft	-	37
47	Thunder Lake	Marinette	A	18 ft	-	37
48	Big Crawling Stone Deep Lake	Vilas	A	17 ft	-	36
49	Ebert Lake	Portage	A	21 ft	-	33
50	Star Lake	Oconto	A	17 ft	-	39
51	Alva Lake	Oneida	A	19.5 ft	-	37
52	Franklin Lake	Forest	A	16 ft	-	38
53	Franklin Lake	Oneida	A	16.2 ft	-	39
54	Rose Lake	Langlade	A	19.5 ft	-	34
55	Sand Lake	Rusk	A	15.3 ft	-	38
56	Sand Lake	Polk	A	20 ft	-	34
57	Cable Lake	Bayfield	A	15.5 ft	-	40
58	Big Portage Lake	Vilas	A	18.5 ft	-	37
59	Crystal Lake	Marquette	A	16.8 ft	-	38
60	Crystal Lake	Bayfield	A	16.2 ft	-	37
61	Crystal Lake	Sheboygan	A	19.9 ft	-	37
62	Rinehart Lake	Portage	A	19 ft	-	38
63	Perch Lake	Langlade	A	17.3 ft	-	39
64	Mildred Lake	Oneida	A	18.5 ft	-	37
65	Half Moon Lake	Polk	A	15.3 ft	-	40
66	White Birch Lake	Vilas	A	16 ft	-	37
67	Forest Lake	Vilas	A	22.2 ft	-	37
68	Pearl Lake	Waushara	A	19 ft	-	36
69	Fish Lake	Waushara	A	-	-	38
70	Sea Lion Lake	Florence	A	21 ft	-	36
71	Upper Eau Claire Lake	Bayfield	A	18.7 ft	-	37
72	Hasbrook Lake	Oneida	A	21 ft	-	36
73	Millicent Lake	Bayfield	A	23 ft	-	32
74	Sunset Lake	Vilas	A	17.4 ft	-	37
75	Black Oak Lake	Vilas	A	28.5 ft	-	33
76	Little Round Lake	Sawyer	A	17.3 ft	-	37
77	Lower Eau Claire Lake	Bayfield	A	18.5 ft	-	35
78	Osprey Lake	Sawyer	A	16 ft	-	38
79	Tozer Lake	Washburn	A	16 ft	-	39
80	Pine Lake	Waukesha	A	25 ft	-	35
81	Bear Paw Lake	Oconto	A	16 ft	-	38
82	Moose Lake	Waukesha	A	16 ft	-	37
83	Mary Lake	Lincoln	A	21 ft	-	33
84	Presque Isle Lake	Vilas	A	18 ft	-	37
85	Leader Lake	Douglas	A	15.3 ft	-	37
86	Keyes Lake	Florence	A	21 ft	-	36
87	Blue Lake	Oneida	A	23 ft	-	35
88	Katinka Lake	Vilas	A	18 ft	-	35
89	Lee Lake	Oneida	A	22.5 ft	-	33
90	Carlin Lake	Vilas	A	24 ft	-	31
91	Dutch Hollow Lake	Sauk	A	15 ft	-	40
92	Middle Kimball Lake	Washburn	A	16 ft	-	39
93	Little Crawling Stone Lake	Vilas	A	15 ft	-	38
94	Two Sisters Lake	Oneida	A	19.6 ft	-	36
95	Crawling Stone Lake	Vilas	A	16 ft	-	37
96	Grindstone Lake	Sawyer	A	17.4 ft	-	38
97	Hart Lake	Bayfield	A	21.5 ft	-	33
98	Clearwater Lake	Oneida	A	16.8 ft	-	37
99	Dorothy Lake	Oneida	A	17 ft	-	36
100	Neligan Lake	Oconto	A	15 ft	-	38

All oligotrophic lakes (MN+WI) →Minnesota version →All Wisconsin lakes →

Source: EPA National Aquatic Resource Surveys, 2026.