Eutrophic Lakes in Illinois

35 eutrophic lakes in Illinois. High nutrients, frequent algae, reduced clarity.

A eutrophic lake is a productive ecosystem with the trade-offs that come with productivity: more food at the base of the food web, more clarity reduction by mid-summer, more dissolved-oxygen variability near the bottom. 35 Illinois lakes register as eutrophic. Only 0% are deep — eutrophy correlates with shallowness, agricultural watersheds, and the kind of nutrient-input history that takes decades to shift.

Eutrophic lakes typically grade C or D on the LakeGrade rubric. The same nutrient richness that defines the trophic class drives the lower grade.

#	Lake	County	Grade	Clarity	Depth	TSI
1	Axehead Lake	Cook	B	11.9 ft	-	48
2	Boulder South Lake	Perry	B	8.8 ft	-	49
3	Wampum Lake	Cook	B	6.9 ft	-	51
4	Shabbona Lake	DeKalb	B	4.9 ft	-	54
5	Big Rock Lake	Kane	B	8.1 ft	-	46
6	Round Lake	Lake	B	7.4 ft	-	49
7	Channel Lake	Lake	B	8 ft	-	52
8	Zurich Lake	Lake	B	-	-	51
9	West Loon Lake	Lake	B	-	-	53
10	George Lake	Rock Island	C	4.2 ft	-	57
11	Wayne City Lake	Wayne	C	2.1 ft	-	62
12	Woods Creek Lake	McHenry	C	3.9 ft	-	59
13	Kinkaid Lake	Jackson	C	-	-	54
14	Tower Lake	Lake	C	-	-	59
15	East Loon Lake	Lake	C	-	-	58
16	Flatfoot Lake	Cook	D	6.2 ft	-	52
17	Turtlehead Lake	Cook	D	2.8 ft	-	62
18	Tampier Lake	Cook	D	1.7 ft	-	67
19	Lake of Egypt	Williamson	D	3.2 ft	-	60
20	Vienna Correctional Center Lake	Johnson	D	4.5 ft	-	56
21	One Horse Gap Lake	Pope	D	4 ft	-	54
22	Pounds Hollow Lake	Gallatin	D	3.9 ft	-	58
23	Tecumseh Lake	Hardin	D	3.6 ft	-	57
24	Lily Lake	McHenry	D	3.3 ft	-	56
25	Sag Quarry West Lake	Cook	D	4.2 ft	-	61
26	Wesslyn Cut Lake	Perry	D	4.5 ft	-	63
27	Poss Lake	DuPage	D	1.2 ft	-	68
28	Decatur Lake	Macon	D	1.3 ft	-	69
29	Olney East Fork Lake	Richland	D	3.2 ft	-	60
30	Monee Lake	Will	D	4.9 ft	-	63
31	Vernor Lake	Richland	D	4.8 ft	-	64
32	Borah Lake	Richland	D	2.2 ft	-	69
33	Fox Lake	Lake	D	1.9 ft	-	66
34	Palmyra-Modesto Lake	Macoupin	D	-	-	64
35	Greenfield Lake	Greene	D	-	-	66

All eutrophic lakes →Minnesota version →Wisconsin 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 →All Illinois lakes →

Source: EPA National Aquatic Resource Surveys, 2026.