Powderhorn Lake is a mesotrophic lake in Cook County, Illinois. 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 67 other monitored lakes in Cook County, Powderhorn Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2021-10-06. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 10.1 ft. Phosphorus level: 13 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.1 ft | B |
| Phosphorus | 13 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Powderhorn Lake
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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.
Recreation & Access
Water Temperature
Powderhorn Lake averages about 78°F at the surface in summer, 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 →
Location
County Ranking
Ranked #4 of 68 lakes in Cook County
Nearby Lakes in Cook County
Explore Powderhorn Lake across LakeGrade
More Illinois Lake Rankings
Other Grade A Lakes in Illinois
Mesotrophic Lakes in Illinois
More records, surveys & data sources
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
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
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.
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)
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: 2021-10-06
Monitoring stations: 3