How Clean Is Green Lake?
Green Lake has fair water quality — typical of lakes with moderate nutrient enrichment. It received a water quality grade of C (Fair) based on EPA monitoring data. Water clarity (Secchi depth): 6 ft. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 6.5 µg/L. Trophic State Index: 50.
Cleanliness Snapshot
| Metric | Green Lake | Minnesota avg |
|---|---|---|
| Overall Grade | C | C |
| Water Clarity (Secchi) | 6 ft | — |
| Phosphorus | 26 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 6.5 µg/L | <10 = clean |
| Trophic State Index | 50 | <50 = clean |
How does Green Lake compare?
Green Lake's grade of C matches or beats the Minnesota state average of C. It ranks #14 of 31 lakes in Chisago County by water quality score. Multi-year monitoring data shows water quality is improving based on 5 years of records.