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LakeQuality
F

Saganashkee Slough Lake

Cook County, WisconsinHypereutrophic

Saganashkee Slough Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, IL. Water quality is graded F based on 2 sampling years through 2020. Compared to the 67 other monitored lakes in Cook County, Saganashkee Slough Lake ranks #67 for water quality.

Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2020-10-20. 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 0.8 ft of visibility. Phosphorus level: 93.5 µg/L. Trophic State Index: 75.

MetricValueGrade
Water Clarity (Secchi Depth)0.8 ftF
Phosphorus93.5 µg/LF
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)75Hypereutrophic

Very high nutrients, dense algae, poor clarity

Location

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County Ranking

Ranked #67 of 68 lakes in Cook County

Cleaner Lakes Within 30 Miles

Saganashkee Slough Lake holds Grade F. 4 nearby lakes hold higher grades.

See full comparison →

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More Wisconsin Lake Rankings

Cleanest lakes in Wisconsin

Top 25 by overall water quality score

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Grade A/B + low algae filter

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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)

Saganashkee Slough Lake is a man-made reservoir impounded by the Saganashkee Slough 1 Dam (completed 1948), built primarily for recreation on the TRIB CALUMET SAG CHANNEL; earth-type dam, 14 ft tall and 950 ft long.

Normal storage
718 ac-ft
Max storage
2,379 ac-ft
Hazard class
Significant
Owner
FOREST PRESERVE DISTRICT OF COOK COUNTY

Source: USACE National Inventory of Dams, NID ID IL00870 · Operator website

EPA Impairment Status

Saganashkee Slough 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 growthMetals (other than mercury)Nutrients (phosphorus, nitrogen)PCBsSediment / turbidityTurbidity

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

Source: EPA ATTAINS assessment unit IL_RHH · Official waterbody report · Matched by proximity (0.05 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: 2020-10-20

Monitoring stations: 3