Sauk Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, Illinois. Water quality is graded F based on 1 sampling years through 2022. Limited fish-species data available. Public access is available. Compared to the 67 other monitored lakes in Cook County, Sauk Lake ranks #48 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-08-25. Grade methodology: LakeGrade methodology.
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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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Sauk Lake
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Fishing Sauk Lake
Location
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.
- APowderhorn LakeCook County · 12.4 mi · Two grade letters higher (F → A)
- BWampum LakeCook County · 6.8 mi · Two grade letters higher (F → B)
- BFlatfoot LakeCook County · 11.8 mi · Two grade letters higher (F → B)
- DMidlothian LakeCook County · 8.5 mi · Higher grade (F → D)
- DMonee LakeWill County · 8.6 mi · Higher grade (F → D)
Nearby Lakes in Cook County
Explore Sauk Lake across LakeGrade
Species activity outlook by water temperature and season
Where to stay at Illinois's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Other Grade F Lakes in Illinois
Hypereutrophic Lakes in Illinois
More records, surveys & data sources
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
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)
Regulated Pollution Sources Nearby
10 EPA-permitted facilities operate within about 5 miles of Sauk Lake under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 6 facilities have a reported Clean Water Act violation in the past three years.
- Thorn Creek Basin Sd StpChicago Heights · 2.6 mi away · NPDES IL0027723MajorRecent violation
- Aqua Illinois - University Park WwtfUniversity Park · 3.2 mi away · NPDES IL0024473MajorRecent violation
- Park Forest Excess Flow Facility, Village OfPark Forest · 1 mi away · NPDES IL0047562Recent violation
- Mid-West Manufacturing Company - Chicago HeightsChicago Heights · 2.2 mi away · NPDES IL0059421Recent violation
- Tcbsd-Homewood Excess Flow Treatment PlantHomewood · 3.1 mi away · NPDES IL0029211Recent violation
- Chicago Heights SteelChicago Heights · 3.2 mi away · NPDES IL0001678Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-08-25
Monitoring stations: 1