Cook County Lake Quality

Illinois, 68 lakes, average grade D (Poor)

Cook County has 68 graded lakes, enough that within-county variation matters as much as the county average. Some are deep glacial basins, others are shallow agricultural-watershed waters, and the grade distribution reflects that mix. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 23 lakes fall into the F bracket outright.

Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Diversey Harbor Lake (A) is the cleanest in the county.

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Quick Answers for Cook County

Cleanest lakes in Cook County →Cleanest lakes in Illinois →Safest swimming lakes in Illinois →

Planning a trip? Check special fishing regulations for Diversey Harbor Lake — or check the official Illinois fishing regulations.

All Lakes in Cook County

Rank	Lake	Grade	Clarity	Phosphorus
1	Diversey Harbor Lake	A	25.6 ft	-
2	Axehead Lake	A	11.9 ft	10 µg/L
3	Powderhorn Lake	A	10.1 ft	13 µg/L
4	Wampum Lake	B	6.9 ft	16 µg/L
5	Lake Calumet	B	-	-
6	Flatfoot Lake	B	6.3 ft	10.5 µg/L
7	Opeka Lake	B	3.9 ft	15.5 µg/L
8	Calumet Lake	B	4.3 ft	10.5 µg/L
9	Icebox Quarry Lake	C	9 ft	-
10	Forge Quarry Lake	C	8.5 ft	-
11	Sag Quarry East Lake	C	5.4 ft	30.5 µg/L
12	Turtlehead Lake	C	2.8 ft	20.5 µg/L
13	Sag Quarry West Lake	C	4.2 ft	52.5 µg/L
14	Lake Opeka	D	4 ft	-
15	Consumers Quarry Lake	D	6.5 ft	-
16	Lake Arlington	D	4.5 ft	-
17	Great Lakes Quarries East	D	4.5 ft	-
18	Flatfoot Lake	D	6 ft	-
19	Papoose Lake	D	5 ft	-
20	Maple Lake	D	5 ft	-
21	Horsetail Lake	D	5 ft	-
22	Sag Quarry-West Lake	D	5.5 ft	-
23	Doughnut Lake	D	5 ft	-
24	Busse Lake Main Pool	D	3.5 ft	-
25	Lake Glenview	D	3.3 ft	-
26	Pogie Lake	D	3.5 ft	-
27	Columbia Basin Lake	D	6 ft	-
28	Jackson Park Inner Harbor Lake	D	5 ft	-
29	Turtlehead Lake	D	6 ft	-
30	Jackson Park West Lagoon Lake	D	5 ft	-
31	Jackson Park Outer Harbor Lake	D	6 ft	-
32	South Pond	D	5.3 ft	-
33	Jackson Park East Lagoon Lake	D	5 ft	-
34	Arrowhead Lake	D	2.1 ft	31.5 µg/L
35	Bullfrog Lake	D	1.4 ft	40.5 µg/L
36	Horsetail Lake	D	2.2 ft	39 µg/L
37	Tampier Lake	D	1.7 ft	38.5 µg/L
38	Midlothian Lake	D	1.2 ft	44.5 µg/L
39	Lake Charlemagne	F	2 ft	-
40	Bode Lake North	F	1.5 ft	-
41	Great Lakes Quarries West	F	2.5 ft	-
42	Bull Frog Lake	F	3 ft	-
43	Belly Deep Slough Lake	F	0.7 ft	-
44	Sauk Lake	F	1 ft	-
45	Crabtree Lake	F	2 ft	-
46	North Pond	F	2.5 ft	-
47	Washington Park Lagoon Lake	F	1.4 ft	-
48	Sherman Park Lagoon Lake	F	1.3 ft	-
49	Tampier Lake	F	2 ft	-
50	Humboldt Park Lagoon Lake	F	1.5 ft	-
51	Big Marsh Park Ne Lake	F	2.3 ft	-
52	Garfield Park Lagoon Lake	F	1.5 ft	-
53	Douglass Park Lagoon Lake	F	1.5 ft	-
54	Mckinley Park Lagoon Lake	F	1.5 ft	-
55	Columbus Park Lagoon Lake	F	2.5 ft	-
56	Marquette Park Lagoon Lake	F	3 ft	-
57	Burnham Prairie Marsh West Lake	F	3.1 ft	-
58	Big Marsh Lake	F	1 ft	-
59	Lake Calumet	F	3 ft	-
60	Saganashkee Slough Lake	F	0.8 ft	93.5 µg/L
61	Skokie Lagoons Lake	F	1.6 ft	155 µg/L