Is Fon-du-Lac Reservoir Safe for Swimming?
Fon-du-Lac Reservoir in Jefferson County, Wisconsin has a water quality grade of F (Very Poor). Avoid swimming, very poor water quality, potential algae toxins. Water clarity: 1.3 ft visibility. Phosphorus: 81 µg/L. Chlorophyll-a (algae): 40.7 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | F (Very Poor) |
| Water Clarity (Secchi Depth) | 1.3 ft |
| Phosphorus | 81 μg/L |
| Chlorophyll-a (Algae) | 40.7 μg/L |
| Location | Jefferson County, Wisconsin |
How does Fon-du-Lac Reservoir compare?
With an overall water quality grade of F, Fon-du-Lac Reservoir falls below the Wisconsin state average of Grade C. It ranks #7 of 7 lakes in Jefferson County by water quality score.
Water clarity (Secchi depth) sits at 1.3 feet. That signals heavy algae or sediment, often tied to high phosphorus from runoff. Algae levels (chlorophyll-a) measure 40.7 µg/L — elevated; risk of harmful algal bloom advisories increases at this concentration.