Saganashkee Slough Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, Illinois. Water quality is graded F based on 2 sampling years through 2020. Limited fish-species data available. Public access is available with 1 public boat landing. 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, Illinois DNR, last sampled 2020-10-20. 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 0.8 ft of visibility. Phosphorus level: 93.5 µg/L. Trophic State Index: 75.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.8 ft | F |
| Phosphorus | 93.5 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 75 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Saganashkee Slough Lake
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Fishing Saganashkee Slough Lake
Recreation & Access
Water Temperature
Saganashkee Slough Lake averages about 80°F at the surface in summer, usually warmest in Jul (about 83°F) and coldest in Oct (about 55°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 22 field readings (2010–2022) via the EPA Water Quality Portal. See the full Saganashkee Slough Lake water temperature breakdown →
Location
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.
- CSag Quarry East LakeCook County · 2 mi · Two grade letters higher (F → C)
- CSag Quarry West LakeCook County · 2.2 mi · Two grade letters higher (F → C)
- DBullfrog LakeCook County · 1.2 mi · Higher grade (F → D)
- DHorsetail LakeCook County · 1.9 mi · Higher grade (F → D)
Nearby Lakes in Cook County
Explore Saganashkee Slough Lake across LakeGrade
Species activity outlook by water temperature and season
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Very high nutrients, dense algae, poor clarity
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More records, surveys & data sources
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
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)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2020-10-20
Monitoring stations: 3