Late afternoon sun over Slim Lake, scattering a bright path across wind-textured water

Cook County Lake Quality

Illinois, 68 lakes, measured by Illinois EPA

Cook County has 68 monitored 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 measurements reflect that mix. 16 of those lakes carry recent nutrient and algae readings. The county-level summary describes that subset, not every water body listed. Most monitored lakes in Cook County are productive, shallow basins; each lake page shows its own phosphorus and chlorophyll-a readings beside the EPA condition class.

The county's lakes lean shallow, which makes the readings sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest measured lake is Lake Opeka.

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Quick Answers for Cook County

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

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

All Lakes in Cook County

68 lakes · 16 ranked on readings, 52 without enough sampling16 lakes ranked on readings · 52 without enough sampling, hidden

Include not-rated lakes (52)

#	Lake	Clarity	Phosphorus	Algae	Trophic	Max Depth	Access
1	Lake OpekaCook	4 ft	22.5 µg/L	5.3 µg/L	No recent samples	No recent samples	Not recorded
2	Lake CalumetCook	4.1 ft	16.5 µg/L	5.4 µg/L	No recent samples	No recent samples	Not recorded
3	Powderhorn LakeCook	10.1 ft	15 µg/L	4.8 µg/L	No recent samples	No recent samples	✓ Public
4	Axehead LakeCook	11.9 ft	17 µg/L	13.8 µg/L	No recent samples	No recent samples	Not recorded
5	Wampum LakeCook	6.9 ft	24 µg/L	10.7 µg/L	No recent samples	No recent samples	Not recorded
6	Flatfoot LakeCook	6.2 ft	18 µg/L	21.3 µg/L	No recent samples	No recent samples	✓ Public
7	Turtlehead LakeCook	2.8 ft	54 µg/L	24.4 µg/L	No recent samples	No recent samples	Not recorded
8	Tampier LakeCook	1.7 ft	83 µg/L	29.7 µg/L	No recent samples	No recent samples	✓ Public
9	Sag Quarry West LakeCook	4.2 ft	65.5 µg/L	22.1 µg/L	No recent samples	No recent samples	Not recorded
10	Horsetail LakeCook	2.2 ft	45 µg/L	39.6 µg/L	No recent samples	No recent samples	Not recorded
11	Saganashkee Slough LakeCook	0.8 ft	170 µg/L	108.5 µg/L	No recent samples	No recent samples	✓ Public
12	Arrowhead LakeCook	2.1 ft	38 µg/L	37.6 µg/L	No recent samples	No recent samples	✓ Public
13	Bullfrog LakeCook	1.4 ft	73 µg/L	124.5 µg/L	No recent samples	No recent samples	Not recorded
14	Sag Quarry East LakeCook	5.4 ft	49 µg/L	37.5 µg/L	No recent samples	No recent samples	Not recorded
15	Skokie Lagoons LakeCook	1.6 ft	229 µg/L	74.7 µg/L	No recent samples	No recent samples	✓ Public
16	Midlothian LakeCook	1.2 ft	121 µg/L	61.5 µg/L	No recent samples	No recent samples	Not recorded
	Consumers Quarry LakeCook	6.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake CharlemagneCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake ArlingtonCook	4.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Great Lakes Quarries EastCook	4.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Bode Lake NorthCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Great Lakes Quarries WestCook	2.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Bull Frog LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Belly Deep Slough LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Papoose LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Sauk LakeCook	1 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Maple LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Sag Quarry-West LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Crabtree LakeCook	2 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Icebox Quarry LakeCook	9 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Forge Quarry LakeCook	8.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Doughnut LakeCook	5 ft	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Busse Lake Main PoolCook	3.5 ft	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Lake GlenviewCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Pogie LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Palatine Marsh South LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Columbia Basin LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	North PondCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Washington Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Jackson Park Inner Harbor LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Jackson Park West Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Sherman Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Humboldt Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Jackson Park Outer Harbor LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Garfield Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Douglass Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	South PondCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Jackson Park East Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Mckinley Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Columbus Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Marquette Park Lagoon LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Diversey Harbor LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public
	Burnham Prairie Marsh West LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Big Marsh LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Big Bend LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	29 ft	✓ Public
	Beck LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	22 ft	✓ Public
	Spring LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Hawley LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	9 ft	Not recorded
	Keene LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Hawthorn LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Baker LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Goose LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Tampier SloughCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Longjohn SloughCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Orland LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Lake Cottage GroveCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Dead Stick PondCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	Not recorded
	Wolf LakeCook	No recent samples	No recent samples	No recent samples	No recent samples	No recent samples	✓ Public

NR = no nutrient or algae reading on record. The measurements are published as the authority reports them. Where the data comes from.

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Source: the Illinois Environmental Protection Agency. See data sources.