Dutchman Lake
Johnson County, WisconsinEutrophic
Dutchman Lake is a productive, nutrient-rich eutrophic lake in Johnson County, IL. Water quality is graded D based on 2 sampling years through 2021. Compared to the 1 other monitored lakes in Johnson County, Dutchman Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2021-10-14. Grade methodology: LakeGrade methodology.
Swimming Safety
Swimming not recommended, poor water quality with high algae risk
Water Quality Grade: D, Poor
Very murky, less than 2.1 ft of visibility. Phosphorus level: 37.5 µg/L. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.1 ft | F |
| Phosphorus | 37.5 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Location
County Ranking
Ranked #2 of 2 lakes in Johnson County
Cleaner Lakes Within 30 Miles
Dutchman Lake holds Grade D. 4 nearby lakes hold higher grades.
- BGlendale LakePope County · 15.4 mi · Two grade letters higher (D → B)
- BOne Horse Gap LakePope County · 26.1 mi · Two grade letters higher (D → B)
- CVienna Correctional Center LakeJohnson County · 10.1 mi · Higher grade (D → C)
- CLake of EgyptWilliamson County · 7.6 mi · Higher grade (D → C)
Nearby Lakes in Johnson County
More Wisconsin Lake Rankings
Other Grade D Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
EPA Impairment Status
Dutchman Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RAM · 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: 2021-10-14
Monitoring stations: 3