Sauk Lake
Cook County, IllinoisView mapDirections
Illinois EPA publishes the water-quality measurements for Sauk Lake. Here is what has been measured.
- Impaired · Algal growth
- Limited data
Sauk Lake in Cook County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1 ft visibility.
Sauk Lake is a lake in Cook County, Illinois.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2022-08-25. Methodology: how these readings are compared.
Vrbo is where to look for cabins and lake homes around Sauk Lake, and Booking.com and Expedia search hotels near the lake for your dates.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Sauk Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pCBs, sediment / turbidity, turbidity. Check local advisories before you swim.
Whether Sauk Lake is safe to swim in today is a call for the Illinois Environmental Protection Agency and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Sauk Lake
These are the measurements Illinois EPA publishes for Sauk Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 1 ft of visibility. TSI 77.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 1ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 77 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Sauk Lake
Answers come straight from the public measurements and survey records on this page.
Stays via Stay22
Stays near Sauk Lake
Compare lakeside cabins, hotels, and vacation rentals near Sauk Lake in Cook County, Illinois — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Sauk Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Illinois’s top lakes →
Follow Sauk Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Sauk 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
Designated uses not supporting: Aquatic life, Other.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RHI · Official waterbody report
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.
Nearby Lakes in Cook County
Frequently asked questions about Sauk Lake
Where is Sauk Lake?
- Sauk Lake is a lake in Cook County, Illinois. Its water-quality measurements are published by Illinois EPA and shown on this page as reported.
What is the water quality of Sauk Lake?
- Sauk Lake in Cook County, Illinois has water-quality measurements published by Illinois EPA, shown here as reported. Water clarity: 1 ft visibility.
Is Sauk Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Sauk Lake is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), oxygen depletion (low DO), pCBs, sediment / turbidity, turbidity. Check local advisories before you swim.
Explore Sauk Lake across LakeQuality
Planning a trip around Indiana Dunes?
Sauk Lake is about 31 miles from Indiana Dunes National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Indiana Dunes →More lakes in Illinois
Other Lakes in Illinois
Hypereutrophic Lakes in Illinois
Where this data comes from
1 measurement from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Illinois Water Science Center
USGS-IL1 sample · 2022
Analytical methods
- Secchi disk method
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)