How Clean Is Portage Lake?
Portage Lake is a clean lake by Minnesota standards. It received a water quality grade of B (Good) based on EPA monitoring data. Water clarity (Secchi depth): 7.5 ft. Phosphorus: 23 µg/L. Chlorophyll-a (algae): 6.1 µg/L. Trophic State Index: 49.
Cleanliness Snapshot
| Metric | Portage Lake | Minnesota avg |
|---|---|---|
| Overall Grade | B | C |
| Water Clarity (Secchi) | 7.5 ft | — |
| Phosphorus | 23 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 6.1 µg/L | <10 = clean |
| Trophic State Index | 49 | <50 = clean |
How does Portage Lake compare?
Portage Lake's grade of B matches or beats the Minnesota state average of C. It ranks #109 of 133 lakes in Cass County by water quality score.