Diversey Harbor Lake
Cook County, WisconsinLimited DataOligotrophic
Diversey Harbor Lake is a cold, clear oligotrophic lake in Cook County, IL. Water quality is graded A based on 1 sampling years through 2023. Compared to the 67 other monitored lakes in Cook County, Diversey Harbor Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2023-05-23. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 25.6 ft down. Trophic State Index: 30.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 25.6 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 30 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Location
County Ranking
Ranked #1 of 68 lakes in Cook County
Nearby Lakes in Cook County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Oligotrophic Lakes in Wisconsin
EPA Impairment Status
Diversey Harbor Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_QZI · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-05-23
Monitoring stations: 1