A
Rock Lake -
Jefferson County, Wisconsin
Water Quality Grade: A — Excellent
Crystal clear — you can see 39.4 feet down. Phosphorus level: 17.9 µg/L.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12 m | A |
| Phosphorus | 17.9 µg/L | A |
| Chlorophyll-a (Algae) | No data |
County Ranking
Ranked #1 of 10 lakes in Jefferson County
Data Sources
Data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-13
Monitoring stations: 1