How Clean Is Long Lake?
Long Lake is among the cleanest lakes in Minnesota. It received a water quality grade of A (Excellent) based on EPA monitoring data. Water clarity (Secchi depth): 21.5 ft. Phosphorus: 9 µg/L. Chlorophyll-a (algae): 3 µg/L. Trophic State Index: 37.
Cleanliness Snapshot
| Metric | Long Lake | Minnesota avg |
|---|---|---|
| Overall Grade | A | C |
| Water Clarity (Secchi) | 21.5 ft | — |
| Phosphorus | 9 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 3 µg/L | <10 = clean |
| Trophic State Index | 37 | <50 = clean |
How does Long Lake compare?
Long Lake's grade of A matches or beats the Minnesota state average of C. It ranks #7 of 104 lakes in Cass County by water quality score. Multi-year monitoring data shows water quality is improving based on 6 years of records.