How Clean Is Johnson Lake?
Johnson 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): 15.7 ft. Phosphorus: 9.5 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Trophic State Index: 38.
Cleanliness Snapshot
| Metric | Johnson Lake | Minnesota avg |
|---|---|---|
| Overall Grade | A | C |
| Water Clarity (Secchi) | 15.7 ft | — |
| Phosphorus | 9.5 µg/L | <30 = clean |
| Chlorophyll-a (Algae) | 2.7 µg/L | <10 = clean |
| Trophic State Index | 38 | <50 = clean |
How does Johnson Lake compare?
Johnson Lake's grade of A matches or beats the Minnesota state average of C. It ranks #31 of 72 lakes in Itasca County by water quality score. Multi-year monitoring data shows water quality is stable based on 6 years of records.