Is Blackduck Lake Safe for Swimming?
Blackduck Lake in St. Louis County, Minnesota has nutrient and algae measurements on record from state and federal monitoring. Chlorophyll-a in the monitoring record runs high enough that algae is a factor. 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: 6.8 ft visibility. Phosphorus: 43 µg/L. Chlorophyll-a (algae): 23.3 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Water Clarity (Secchi Depth) | 6.8 ft |
| Phosphorus | 43 μg/L |
| Chlorophyll-a (Algae) | 23.3 μg/L |
| Maximum Depth | 30 ft |
| Location | St. Louis County, Minnesota |
How does Blackduck Lake compare?
With an overall water-quality readings of —, Blackduck Lake runs above the Minnesota state average. It ranks #66 of 68 lakes in St. Louis County by water quality score.
Water clarity (Secchi depth) sits at 6.8 feet. That puts the lake in good clarity range, with limited algae interference. Algae levels (chlorophyll-a) measure 23.3 µg/L — elevated; risk of harmful algal bloom advisories increases at this concentration.
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