How Clean Is Union Lake?
Union 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): 3 ft. Phosphorus: 1.4 µg/L. Trophic State Index: 35.
Cleanliness Snapshot
| Metric | Union Lake | Minnesota avg |
|---|---|---|
| Overall Grade | C | C |
| Water Clarity (Secchi) | 3 ft | — |
| Phosphorus | 1.4 µg/L | <30 = clean |
| Trophic State Index | 35 | <50 = clean |
How does Union Lake compare?
Union Lake's grade of C matches or beats the Minnesota state average of C. It ranks #2 of 12 lakes in Rice County by water quality score. Multi-year monitoring data shows water quality is declining based on 2 years of records.