Is Big Hollow Lake Safe for Swimming?
Big Hollow Lake in Des Moines County, Wisconsin has a water quality grade of F (Very Poor). Avoid swimming, very poor water quality, potential algae toxins. Water clarity: 1.8 ft visibility. Chlorophyll-a (algae): 46 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | F (Very Poor) |
| Water Clarity (Secchi Depth) | 1.8 ft |
| Chlorophyll-a (Algae) | 46 μg/L |
| Location | Des Moines County, Wisconsin |
How does Big Hollow Lake compare?
With an overall water quality grade of F, Big Hollow Lake falls below the Wisconsin state average of Grade D. It ranks #1 of 2 lakes in Des Moines County by water quality score.
Water clarity (Secchi depth) sits at 1.8 feet. That signals heavy algae or sediment, often tied to high phosphorus from runoff. Algae levels (chlorophyll-a) measure 46 µg/L — elevated; risk of harmful algal bloom advisories increases at this concentration.