How Clean Is Mill Lake?
Mill 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): 11 ft. Phosphorus: 23 µg/L. Chlorophyll-a (algae): 9 µg/L. Trophic State Index: 48.
Cleanliness Snapshot
| Metric | Mill Lake | Minnesota avg |
|---|---|---|
| Overall Grade | C | C |
| Water Clarity (Secchi) | 11 ft | — |
| Phosphorus | 23 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 9 µg/L | <10 = clean |
| Trophic State Index | 48 | <50 = clean |
How does Mill Lake compare?
Mill Lake's grade of C matches or beats the Minnesota state average of C. It ranks #27 of 37 lakes in Douglas County by water quality score. Multi-year monitoring data shows water quality is declining based on 3 years of records.