How Clean Is Duncan Lake?
Duncan 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): 22 ft. Trophic State Index: 33.
Cleanliness Snapshot
| Metric | Duncan Lake | Minnesota avg |
|---|---|---|
| Overall Grade | A | C |
| Water Clarity (Secchi) | 22 ft | — |
| Trophic State Index | 33 | <50 = clean |
How does Duncan Lake compare?
Duncan Lake's grade of A matches or beats the Minnesota state average of C. It ranks #10 of 128 lakes in Cook County by water quality score. Multi-year monitoring data shows water quality is declining based on 5 years of records.