Big Marsh Lake
Cook County, WisconsinLimited DataHypereutrophic
Big Marsh Lake is a highly nutrient-loaded hypereutrophic lake in Cook County, IL. Water quality is graded F based on 1 sampling years through 2023. Compared to the 67 other monitored lakes in Cook County, Big Marsh Lake ranks #65 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2023-04-26. Grade methodology: LakeGrade methodology.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1 ft of visibility. Trophic State Index: 77.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 77 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Location
County Ranking
Ranked #65 of 68 lakes in Cook County
Cleaner Lakes Within 30 Miles
Big Marsh Lake holds Grade F. 2 nearby lakes hold higher grades.
- BCalumet LakeCook County · 1.2 mi · Two grade letters higher (F → B)
- BFlatfoot LakeCook County · 2.8 mi · Two grade letters higher (F → B)
Nearby Lakes in Cook County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
Hypereutrophic Lakes in Wisconsin
EPA Impairment Status
Big Marsh 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_RHO · Official waterbody report · Matched by proximity (1.71 km)
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: 2023-04-26
Monitoring stations: 1