A
Oconomowoc Lake -
Washington County, Wisconsin
Water Quality Grade: A — Excellent
Crystal clear — you can see 42.7 feet down. Phosphorus level: 11.7 µg/L.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13 m | A |
| Phosphorus | 11.7 µg/L | A |
| Chlorophyll-a (Algae) | No data |
County Ranking
Ranked #17 of 68 lakes in Washington County
Data Sources
Data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-09-12
Monitoring stations: 1