Johnson Lake
Beltrami County, MinnesotaMesotrophic
On the LakeGrade scale Johnson Lake grades a B, with clarity at 7.5 ft and 24 µg/L of phosphorus placing it above the Minnesota median. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.
The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Johnson Lake sits at rank 68 of 92 in Beltrami County, in the lower half of the local distribution.
No invasive species are currently listed at Johnson Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Johnson Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-17. Grade methodology: LakeGrade methodology.
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Moderate clarity, visible to about 7.5 ft. Phosphorus level: 24 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.5 ft | C |
| Phosphorus | 24 µg/L | B |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.207 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.6 µg/L/yr | 6 |
Location
County Ranking
Ranked #68 of 92 lakes in Beltrami County
Cleaner Lakes Within 30 Miles
Johnson Lake holds Grade B. 2 nearby lakes hold higher grades.
- ASandy LakeBeltrami County · mi · Higher grade (B → A)
- ARound LakeBeltrami County · mi · Higher grade (B → A)
Nearby Lakes in Beltrami County
More Minnesota Lake Rankings
Other Grade B Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-09-17
Monitoring stations: 1