What are oligotrophic lakes in Wisconsin?

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

What does oligotrophic mean?

Low nutrients, clear water, excellent for swimming.

Oligotrophic Lakes in Wisconsin

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, 127 lakes register as oligotrophic — 39% 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 our A–F scale, 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	21 ft	135 ft	37
2	Whitefish Lake	Sawyer	A	13.5 ft	105 ft	39
3	Round Lake	Sawyer	A	21.1 ft	74 ft	35
4	Blueberry Lake	Sawyer	A	14.8 ft	29 ft	40
5	Little Round Lake	Sawyer	A	17.3 ft	38 ft	36
6	Osprey Lake	Sawyer	A	16 ft	32 ft	38
7	Grindstone Lake	Sawyer	A	17.4 ft	60 ft	38
8	Oneida Lake	Outagamie	A	-	-	39
9	Mission Lake	Shawano	A	17.5 ft	44 ft	40
10	King Lake	Marinette	A	-	70 ft	32
11	Bug Lake	Forest	A	-	-	34
12	Cloud Lake	Forest	A	-	25 ft	37
13	Plum Lake	Vilas	B	14.2 ft	57 ft	40
14	Whitefish Lake	Douglas	B	25 ft	102 ft	35
15	Round Lake	Oconto	B	16.8 ft	31 ft	39
16	Deep Lake	Adams	B	15.5 ft	49 ft	39
17	Beasley Lake	Waupaca	B	18.4 ft	47 ft	39
18	Bass Lake	Washburn	B	16 ft	31 ft	39
19	Bass Lake	Oconto	B	16.8 ft	40 ft	37
20	Clear Lake	Sawyer	B	17.3 ft	32 ft	38
21	Clear Lake	Rusk	B	13.7 ft	74 ft	40
22	Clear Lake	Polk	B	15.5 ft	26 ft	40
23	Clear Lake	Lincoln	B	18 ft	45 ft	37
24	Clear Lake	Oneida	B	-	95 ft	38
25	Explosion Lake	Oconto	B	17 ft	10 ft	39
26	Sugar Camp Lake	Oneida	B	16.5 ft	-	37
27	Little Spider Lake	Vilas	B	16 ft	23 ft	38
28	Marl Lake	Waupaca	B	13.6 ft	59 ft	39
29	Rosalind Lake	Vilas	B	19.3 ft	-	36
30	Lake Lucerne	Forest	B	18.7 ft	73 ft	36
31	Long Lake	Bayfield	B	16.2 ft	28 ft	39
32	Long Lake	Burnett	B	21.5 ft	41 ft	36
33	Long Lake	Waushara	B	14.5 ft	71 ft	39
34	Long Lake	Lincoln	B	14.5 ft	64 ft	40
35	Lake Metonga	Forest	B	22 ft	79 ft	37
36	Anderson Lake	Vilas	B	20.5 ft	63 ft	36
37	Archibald Lake	Oconto	B	17.8 ft	50 ft	37
38	Carlin Lake	Vilas	B	21 ft	36 ft	33
39	Wolf Lake	Adams	B	15 ft	58 ft	39
40	Butternut Lake	Forest	B	19.5 ft	42 ft	37
41	Stone Lake	Washburn	B	23 ft	49 ft	35
42	Paya Lake	Oconto	B	20 ft	40 ft	37
43	Samoset Lake	Bayfield	B	15 ft	40 ft	40
44	North Twin Lake	Polk	B	-	27 ft	37
45	Papoose Lake	Vilas	B	15 ft	65 ft	38
46	Boot Lake	Oconto	B	21.5 ft	38 ft	36
47	Eagle Lake	Bayfield	B	17 ft	52 ft	40
48	Little Hills Lake	Waushara	B	14 ft	20 ft	40
49	White Lake	Marquette	B	17 ft	60 ft	37
50	Upper Kaubashine Lake	Oneida	B	19 ft	56 ft	37
51	Squash Lake	Oneida	B	17.5 ft	74 ft	37
52	Plummer Lake	Vilas	B	18 ft	85 ft	38
53	Thunder Lake	Marinette	B	18 ft	62 ft	37
54	Star Lake	Oconto	B	17 ft	21 ft	39
55	Diamond Lake	Bayfield	B	13 ft	83 ft	40
56	Alva Lake	Oneida	B	19.5 ft	43 ft	37
57	Franklin Lake	Forest	B	16 ft	46 ft	38
58	Franklin Lake	Oneida	B	16.2 ft	25 ft	39
59	Charnley Lake	Iron	B	13.5 ft	-	39
60	Cable Lake	Bayfield	B	15.5 ft	-	40
61	Big Portage Lake	Vilas	B	18.5 ft	40 ft	38
62	Crystal Lake	Marquette	B	16.8 ft	60 ft	38
63	Crystal Lake	Sheboygan	B	20 ft	-	37
64	Rinehart Lake	Portage	B	19 ft	27 ft	38
65	Perch Lake	Langlade	B	17.3 ft	21 ft	39
66	Mildred Lake	Oneida	B	18 ft	45 ft	38
67	Half Moon Lake	Polk	B	15.3 ft	60 ft	40
68	Manson Lake	Oneida	B	12 ft	54 ft	40
69	Forest Lake	Vilas	B	22.2 ft	60 ft	37
70	Pearl Lake	Waushara	B	19 ft	45 ft	37
71	Fish Lake	Burnett	B	14 ft	-	40
72	Wood Lake	Marquette	B	14 ft	53 ft	39
73	Sea Lion Lake	Florence	B	21 ft	82 ft	36
74	Lower Kaubashine Lake	Oneida	B	13.8 ft	36 ft	39
75	Upper Eau Claire Lake	Bayfield	B	18.7 ft	92 ft	37
76	Hasbrook Lake	Oneida	B	21 ft	50 ft	36
77	Sunset Lake	Vilas	B	17.3 ft	30 ft	38
78	Black Oak Lake	Vilas	B	29 ft	85 ft	33
79	Flannery Lake	Oneida	B	14.5 ft	35 ft	40
80	Clark Lake	Door	B	12.5 ft	25 ft	39
81	Fishtrap Lake	Vilas	B	12.2 ft	34 ft	40
82	Lynx Lake	Vilas	B	12.8 ft	20 ft	39
83	Seven Island Lake	Lincoln	B	14 ft	31 ft	38
84	Tozer Lake	Washburn	B	16 ft	53 ft	39
85	Pine Lake	Waukesha	B	25 ft	85 ft	35
86	Bear Paw Lake	Oconto	B	16 ft	20 ft	38
87	Presque Isle Lake	Vilas	B	18 ft	103 ft	37
88	Leader Lake	Douglas	B	15.3 ft	56 ft	38
89	Keyes Lake	Florence	B	21 ft	-	36
90	Blue Lake	Oneida	B	23 ft	49 ft	35
91	Lee Lake	Oneida	B	22.5 ft	44 ft	34
92	Dutch Hollow Lake	Sauk	B	15 ft	38 ft	40
93	Hammil Lake	Bayfield	B	14.6 ft	47 ft	39
94	Middle Kimball Lake	Washburn	B	16 ft	77 ft	39
95	Two Sisters Lake	Oneida	B	19.6 ft	-	36
96	Crawling Stone Lake	Vilas	B	16 ft	87 ft	38
97	Clearwater Lake	Oneida	B	16.8 ft	48 ft	37
98	Middle Eau Claire Lake	Bayfield	B	18.2 ft	66 ft	38
99	Gilas Lake	Marinette	B	15 ft	88 ft	39
100	South Twin Lake	Washburn	B	14 ft	29 ft	39

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 →Ontario version →Québec version →Nova Scotia version →British Columbia version →Newfoundland and Labrador version →All Wisconsin lakes →

Source: EPA National Aquatic Resource Surveys, 2026.