What are eutrophic lakes in Illinois?

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

What does eutrophic mean?

High nutrients, frequent algae, reduced clarity.

Eutrophic Lakes in Illinois

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 carry higher phosphorus and chlorophyll-a readings. The same nutrient richness that defines the trophic class shows up in those numbers.

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

Source: EPA National Aquatic Resource Surveys, 2026.