What are hypereutrophic lakes in Illinois?

52 hypereutrophic lakes in Illinois. Very high nutrients, dense algae, poor clarity.

What does hypereutrophic mean?

Very high nutrients, dense algae, poor clarity.

Hypereutrophic Lakes in Illinois

Hypereutrophic lakes (TSI above 70) are at the upper end of the productivity scale: visible algal blooms most weeks of summer, clarity often under 3 feet, and meaningful risk of harmful-algal-bloom toxin events. 52 hypereutrophic lakes are on the Illinois books. Almost none of them are deep — 0% break 50 feet. Shallow basin plus heavy nutrient input is the consistent recipe.

Hypereutrophic lakes carry the highest phosphorus and chlorophyll-a readings on record; the trophic class and the readings are measuring closely related dimensions of the same underlying nutrient regime.

#	Lake	County	Clarity	Depth	TSI
1	Horsetail Lake	Cook	2.2 ft	-	64
2	Long Lake	Lake	3.4 ft	-	66
3	Salem Lake	Marion	1 ft	-	78
4	Saganashkee Slough Lake	Cook	0.8 ft	-	79
5	Glendale Lake	Pope	4.8 ft	-	57
6	Vandalia Lake	Fayette	1.3 ft	-	73
7	Arrowhead Lake	Cook	2.1 ft	-	63
8	Bullfrog Lake	Cook	1.4 ft	-	72
9	Holiday Shores Lake	Madison	1.7 ft	-	70
10	Sag Quarry East Lake	Cook	5.4 ft	-	60
11	Dutchman Lake	Johnson	2.1 ft	-	65
12	Forbes Lake	Marion	1.4 ft	-	74
13	Mermet Lake	Massac	1.6 ft	-	73
14	Skokie Lagoons Lake	Cook	1.6 ft	-	75
15	Randolph Lake	Randolph	1.7 ft	-	69
16	Centralia Lake	Marion	1.5 ft	-	73
17	Sam Dale Lake	Wayne	1.2 ft	-	77
18	Raccoon Lake	Marion	1.2 ft	-	78
19	Carlyle Lake	Clinton	1.8 ft	-	73
20	Midlothian Lake	Cook	1.2 ft	-	73
21	Slm Side Channel Lake	St. Clair	0.8 ft	-	81
22	Fairfield Lake	Wayne	1.3 ft	-	72
23	Sparta Northwest Lake	Randolph	2.6 ft	-	62
24	Glenn Shoals Lake	Montgomery	1 ft	-	74
25	Mattoon Lake	Cumberland	1.3 ft	-	78
26	Sara Lake	Effingham	2.2 ft	-	65
27	Otter Lake	Macoupin	1.8 ft	-	67
28	Lou Yaeger Lake	Montgomery	1.8 ft	-	75
29	Grass Lake	Lake	1.4 ft	-	70
30	Newton Lake	Jasper	1.7 ft	-	70
31	Governor Bond Lake	Bond	1.2 ft	-	76
32	Nashville City Lake	Washington	1.3 ft	-	81
33	Marie Lake	Lake	2.7 ft	-	66
34	Jacksonville Lake	Morgan	1.8 ft	-	66
35	Highland Silver Lake	Madison	1.3 ft	-	72
36	Pistakee Lake	McHenry	2.7 ft	-	65
37	Canton Lake	Fulton	2.5 ft	-	65
38	Kinmundy Old Lake	Marion	1.5 ft	-	78
39	Nippersink Lake	Lake	1.3 ft	-	70
40	Kinmundy New Lake	Marion	2.9 ft	-	63
41	Coulterville Lake	Randolph	2.7 ft	-	75
42	Paradise Lake	Pike	-	-	78
43	Paradise Lake	Coles	-	-	74
44	Charleston Side Channel Lake	Coles	-	-	72
45	Loveless Lake	Macoupin	-	-	67
46	Vermont City Lake	McDonough	-	-	71
47	Mauvaise Terre Lake	Morgan	-	-	74
48	Diamond Lake	Lake	-	-	71
49	Valley Lake	Lake	-	-	69
50	Louise Lake	Lake	-	-	74
51	Slocum Lake	Lake	-	-	75
52	Island Lake	McHenry	-	-	79

All hypereutrophic 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.