D
Lake Koshkonong
Jefferson County, Wisconsin
Water Quality Grade: D — Poor
Murky — only visible to about 5.7 feet. Phosphorus level: 287 µg/L.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.75 m | D |
| Phosphorus | 287 µg/L | F |
| Chlorophyll-a (Algae) | No data |
Location
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County Ranking
Ranked #8 of 8 lakes in Jefferson County
Data Sources
Data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-09
Monitoring stations: 4