How Clean Is Delavan Lake?
Delavan 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): 8 ft. Phosphorus: 49.5 µg/L. Trophic State Index: 54.
Cleanliness Snapshot
| Metric | Delavan Lake | Wisconsin avg |
|---|---|---|
| Overall Grade | C | C |
| Water Clarity (Secchi) | 8 ft | — |
| Phosphorus | 49.5 µg/L | <30 = clean |
| Trophic State Index | 54 | <50 = clean |
How does Delavan Lake compare?
Delavan Lake's grade of C matches or beats the Wisconsin state average of C. It ranks #20 of 34 lakes in Walworth County by water quality score. Multi-year monitoring data shows water quality is declining based on 6 years of records.