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LakeQuality
F

Sauk Lake

Cook County, WisconsinLimited DataHypereutrophic

Sauk Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, IL. Water quality is graded F based on 1 sampling years through 2022. Compared to the 67 other monitored lakes in Cook County, Sauk Lake ranks #48 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2022-08-25. Grade methodology: LakeGrade methodology.

Swimming Safety

Avoid swimming, very poor water quality, potential algae toxins

Water Quality Grade: F, Very Poor

Very murky, less than 1 ft of visibility. Trophic State Index: 77.

MetricValueGrade
Water Clarity (Secchi Depth)1 ftF
PhosphorusNo data
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)77Hypereutrophic

Very high nutrients, dense algae, poor clarity

Location

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County Ranking

Ranked #48 of 68 lakes in Cook County

Cleaner Lakes Within 30 Miles

Sauk Lake holds Grade F. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Cook County

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Powderhorn Lake
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Wampum Lake
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Lake Calumet
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More Wisconsin Lake Rankings

Cleanest lakes in Wisconsin

Top 25 by overall water quality score

Best swimming lakes in Wisconsin

Grade A/B + low algae filter

Family fishing lakes in Wisconsin

Panfish-rich, public access

All Wisconsin lakes

Full state directory

Other Grade F Lakes in Wisconsin

Salem Lake

Marion County · Clarity: 1 ft

Lake Springfield

Sangamon County · Clarity: 1.5 ft

Vandalia Lake

Fayette County · Clarity: 1.3 ft

Holiday Shores Lake

Madison County · Clarity: 1.7 ft

Sam Dale Lake

Wayne County · Clarity: 1.2 ft

Raccoon Lake

Marion County · Clarity: 1.2 ft

Hypereutrophic Lakes in Wisconsin

Salem LakeLake SpringfieldVandalia LakeHoliday Shores Lake

Reservoir Info (USACE NID)

Sauk Lake is a man-made reservoir impounded by the Sauk Trail Lake Dam (completed 1923), built primarily for recreation on the THORN CREEK; earth-type dam, 18 ft tall and 355 ft long.

Normal storage
122 ac-ft
Max storage
376 ac-ft
Hazard class
Low
Owner
FOREST PRESERVE DISTRICT OF COOK COUNTY

Source: USACE National Inventory of Dams, NID ID IL00868 · Operator website · Matched by proximity (0.43 km)

EPA Impairment Status

Sauk Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Algal growthNutrients (phosphorus, nitrogen)Oxygen depletion (low DO)PCBsSediment / turbidityTurbidity

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit IL_RHI · Official waterbody report · Matched by proximity (0.15 km)

Data Sources

Water quality data from the EPA Water Quality Portal

Impairment status from EPA ATTAINS 303(d) database

Grading methodology based on Metropolitan Council standards

Most recent sample: 2022-08-25

Monitoring stations: 1