Powderhorn Lake
Cook County, IllinoisView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Mesotrophic
- Impaired · Mercury
- Round Goby
- #3 of 16 in the county
- 43 ft max depth
- Public access
- Limited data
Powderhorn Lake in Cook County, Illinois has a water quality grade of A (Excellent). Water clarity: 10.1 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 4.8 µg/L.
- Clarity
- 10.1 ft
- Typical in August
- 83°F
- Max depth
- ~43 ft est.
- Type
- Mesotrophic
- Public access
- Yes
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Watch Powderhorn Lake’s letter
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Powderhorn Lake is a mesotrophic lake in Cook County, Illinois with an estimated average depth of about 43 feet. Water quality is graded A based on 2 sampling years through 2021. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 15 other monitored lakes in Cook County, Powderhorn Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois EPA, last sampled 2021-10-06. Grade methodology: LakeQuality methodology.
What Powderhorn Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.1 ft of visibility
- Boat launch1 documented ramp
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, not a swimming clearance. Powderhorn Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pesticides, pCBs. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Good clarity, visible to about 10.1 ft. Phosphorus 15 µg/L. Chlorophyll-a 4.8 µg/L. TSI 44. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.1 ft | Not graded |
| Phosphorus | 15 µg/L | Good |
| Chlorophyll-a (Algae) | 4.8 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Water Temperature
Powderhorn Lake typically sits around 83°F at the surface in August. Summer average is about 78°F. Usually warmest in Aug (about 83°F) and coldest in May (about 61°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 347 field readings (2011–2022) via the EPA Water Quality Portal. See the full Powderhorn Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~43 ft est. |
| Average Depth | ~8 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Illinois has not published bathymetry for Powderhorn Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Powderhorn LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Powderhorn Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
EPA Impairment Status
Powderhorn Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit IL_RHG · Official waterbody report
Regulated Pollution Sources Nearby
107 EPA-permitted facilities operate within about 5 miles of Powderhorn Lake under Clean Water Act (NPDES) discharge permits, including 2 classified by the EPA as major dischargers. 3 facilities have a reported Clean Water Act violation in the past three years.
- Hammond Wastewater FacilityHammond · 2.4 mi away · NPDES IN0023060MajorRecent violation
- East Chicago Sanitary DistrictEast Chicago · 3 mi away · NPDES IN0022829MajorRecent violation
- Wr Grace & CoEast Chicago · 4.4 mi away · NPDES IN0000329Recent violation
- Chicago Street Widening And Reconstruction Phase 1Hammond · 0.2 mi away · NPDES INRA03343
- Chicago Street Widening & Reconstruction - Phase IiiHammond · 0.3 mi away · NPDES INR10N045
- Chicago Street Widening & Reconstruction Project - Part I - Advanced ClearingHammond · 0.6 mi away · NPDES INR10N050
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.
County Ranking
Ranked #3 of 16 lakes in Cook County
Nearby Lakes in Cook County
Frequently asked questions about Powderhorn Lake
Where is Powderhorn Lake?
- Powderhorn Lake is a lake in Cook County, Illinois. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Powderhorn Lake?
- Powderhorn Lake in Cook County, Illinois has a water quality grade of A (Excellent). Water clarity: 10.1 ft visibility. Phosphorus: 15 µg/L. Chlorophyll-a (algae): 4.8 µg/L.
Is Powderhorn Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Powderhorn Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pesticides, pCBs. Check local advisories before you swim.
What is the water temperature of Powderhorn Lake?
- Powderhorn Lake typically sits around 83°F at the surface in August, from 347 EPA Water Quality Portal field readings (2011–2022). That is a typical value for the month, not a live reading.
How deep is Powderhorn Lake?
- No published bathymetric survey covers Powderhorn Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 43 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Powderhorn Lake?
- Powderhorn Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Powderhorn Lake. Public access is listed as yes.
Explore Powderhorn Lake across LakeQuality
Planning a trip around Indiana Dunes?
Powderhorn Lake is about 22 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 Illinois Lake Rankings
Other Grade A Lakes in Illinois
Mesotrophic Lakes in Illinois
Where this data comes from
52 measurements from 3 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- illinois epa
IL_EPA_WQX52 samples · 2021
Analytical methods
- MEASURED IN FIELD
- Phosphorus by Colorimetry
- 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (3)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory