How Clean Is Long Island Lake?
Long Island 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. Trophic State Index: 47.
Cleanliness Snapshot
| Metric | Long Island Lake | Minnesota avg |
|---|---|---|
| Overall Grade | C | C |
| Water Clarity (Secchi) | 8 ft | — |
| Trophic State Index | 47 | <50 = clean |
How does Long Island Lake compare?
Long Island Lake's grade of C matches or beats the Minnesota state average of C. It ranks #94 of 128 lakes in Cook County by water quality score. Multi-year monitoring data shows water quality is stable based on 2 years of records.