Belly Deep Slough Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, Illinois. Water quality is graded F based on 1 sampling years through 2022. Compared to the 67 other monitored lakes in Cook County, Belly Deep Slough Lake ranks #47 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-03-22. 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 0.7 ft of visibility. Trophic State Index: 83.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.7 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 83 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Belly Deep Slough Lake
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Fishing Belly Deep Slough Lake
Location
County Ranking
Ranked #47 of 68 lakes in Cook County
Cleaner Lakes Within 30 Miles
Belly Deep Slough Lake holds Grade F. 3 nearby lakes hold higher grades.
Nearby Lakes in Cook County
Explore Belly Deep Slough 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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More records, surveys & data sources
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Belly Deep Slough Lake under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Vcna Prairie LlcBridgeview · 3.3 mi away · NPDES IL0078590Recent violation
- Westlake Epoxy, IncBedford Park · 3.7 mi away · NPDES IL0075205Recent violation
- Ingredion Incorporated Argo PlantBedford Park · 4.6 mi away · NPDES IL0041009Recent violation
- Mccook ResevoirWillow Springs · 3 mi away · NPDES IL0079138
- Golden Grain Co-BridgeviewBridgeview · 4.1 mi away · NPDES IL0073342
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2022-03-22
Monitoring stations: 1