How Clean Is Green Lake?
Green Lake has poor water quality, with elevated phosphorus and algae. It received a water quality grade of D (Poor) based on EPA monitoring data. Water clarity (Secchi depth): 4.7 ft. Phosphorus: 48 µg/L. Chlorophyll-a (algae): 16.4 µg/L. Trophic State Index: 58.
Cleanliness Snapshot
| Metric | Green Lake | Minnesota avg |
|---|---|---|
| Overall Grade | D | C |
| Water Clarity (Secchi) | 4.7 ft | — |
| Phosphorus | 48 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 16.4 µg/L | <10 = clean |
| Trophic State Index | 58 | <50 = clean |
How does Green Lake compare?
Green Lake's grade of D falls below the Minnesota state average of C. It ranks #12 of 17 lakes in Isanti County by water quality score. Multi-year monitoring data shows water quality is improving based on 5 years of records.