Is Colby Lake Safe for Swimming?
Colby Lake in St. Louis County, Minnesota has nutrient and algae measurements on record from state and federal monitoring. A water-quality reading is not a swimming clearance. The state water agency and county health departments post current advisories; check them before you swim.. Water clarity: 3 ft visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 3.2 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Water Clarity (Secchi Depth) | 3 ft |
| Phosphorus | 22 μg/L |
| Chlorophyll-a (Algae) | 3.2 μg/L |
| Maximum Depth | 30 ft |
| Location | St. Louis County, Minnesota |
How does Colby Lake compare?
On nutrient and algae readings, Colby Lake matches or beats the Minnesota state average. It ranks #3 of 68 lakes in St. Louis County on nutrient and algae readings.
Water clarity (Secchi depth) sits at 3 feet. That falls into moderate clarity — typical for lakes with some nutrient enrichment. Algae levels (chlorophyll-a) measure 3.2 µg/L — low and well within safe swimming guidelines.
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