How Clean Is Marion Lake?
Marion 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): 11 ft. Phosphorus: 18 µg/L. Chlorophyll-a (algae): 7.3 µg/L. Trophic State Index: 46.
Cleanliness Snapshot
| Metric | Marion Lake | Minnesota avg |
|---|---|---|
| Overall Grade | B | C |
| Water Clarity (Secchi) | 11 ft | — |
| Phosphorus | 18 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 7.3 µg/L | <10 = clean |
| Trophic State Index | 46 | <50 = clean |
How does Marion Lake compare?
Marion Lake's grade of B matches or beats the Minnesota state average of C. It ranks #51 of 66 lakes in Otter Tail County by water quality score. Multi-year monitoring data shows water quality is improving based on 6 years of records.