Is Portage Lake Safe for Swimming?
Portage Lake in Cass 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: 7.5 ft visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 7.1 µg/L. Always check local health department advisories before swimming.
Key Metrics
| Metric | Value |
|---|---|
| Water Clarity (Secchi Depth) | 7.5 ft |
| Phosphorus | 22 μg/L |
| Chlorophyll-a (Algae) | 7.1 μg/L |
| Maximum Depth | 55 ft |
| Location | Cass County, Minnesota |
How does Portage Lake compare?
On nutrient and algae readings, Portage Lake matches or beats the Minnesota state average. It ranks #88 of 104 lakes in Cass County on nutrient and algae readings.
Water clarity (Secchi depth) sits at 7.5 feet. That puts the lake in good clarity range, with limited algae interference. Algae levels (chlorophyll-a) measure 7.1 µg/L — moderate; acceptable for swimming on most days, but worth checking advisories.
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