Is Alder Lake Safe for Swimming?
Alder Lake in Cook County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Not rated for swimming — there is not enough monitoring data to judge this lake. Water clarity: 13.8 ft visibility. Phosphorus: 8 µg/L. Chlorophyll-a (algae): 3.1 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Overall Grade | NR (Not rated) |
| Water Clarity (Secchi Depth) | 13.8 ft |
| Phosphorus | 8 μg/L |
| Chlorophyll-a (Algae) | 3.1 μg/L |
| Maximum Depth | 72 ft |
| Location | Cook County, Minnesota |
How does Alder Lake compare?
Alder Lake is not rated for water quality — its monitoring record does not meet the evidence bar, so it is not compared with the Minnesota state average.
Water clarity (Secchi depth) sits at 13.8 feet. That counts as exceptional clarity — sunlight penetrates deep, supporting submerged plants and limiting algae. Algae levels (chlorophyll-a) measure 3.1 µg/L — low and well within safe swimming guidelines.