Is Mill Lake Safe for Swimming?
Mill Lake in Douglas County, Minnesota has a water quality grade of C (Fair). Generally safe for swimming, moderate water quality. Water clarity: 11 ft visibility. Phosphorus: 23 µg/L. Chlorophyll-a (algae): 9 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | C (Fair) |
| Water Clarity (Secchi Depth) | 11 ft |
| Phosphorus | 23 μg/L |
| Chlorophyll-a (Algae) | 9 μg/L |
| Maximum Depth | 40 ft |
| Location | Douglas County, Minnesota |
How does Mill Lake compare?
With an overall water quality grade of C, Mill Lake matches or beats the Minnesota state average of Grade C. It ranks #27 of 37 lakes in Douglas County by water quality score.
Water clarity (Secchi depth) sits at 11 feet. That counts as exceptional clarity — sunlight penetrates deep, supporting submerged plants and limiting algae. Algae levels (chlorophyll-a) measure 9 µg/L — moderate; acceptable for swimming on most days, but worth checking advisories.