Is Big Lake Safe for Swimming?
Big Lake in Carlton County, Minnesota has a water quality grade of A (Excellent). Excellent for swimming, crystal clear water with minimal algae. Water clarity: 10 ft visibility. Phosphorus: 13.5 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | A (Excellent) |
| Water Clarity (Secchi Depth) | 10 ft |
| Phosphorus | 13.5 μg/L |
| Chlorophyll-a (Algae) | 3.2 μg/L |
| Maximum Depth | 25 ft |
| Location | Carlton County, Minnesota |
How does Big Lake compare?
With an overall water quality grade of A, Big Lake matches or beats the Minnesota state average of Grade C. It ranks #1 of 22 lakes in Carlton County by water quality score.
Water clarity (Secchi depth) sits at 10 feet. That counts as exceptional clarity — sunlight penetrates deep, supporting submerged plants and limiting algae. Algae levels (chlorophyll-a) measure 3.2 µg/L — low and well within safe swimming guidelines.