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B

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.

Reviewed by LakeQuality Editorial Team · Updated

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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.

MetricValueGrade
Water Clarity (Secchi Depth)7.5 ftC
Phosphorus24 µg/LB
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)49Mesotrophic

Moderate nutrients, good water quality

Water Quality Trend: Improving

Based on 6 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.207 m/yr6
Phosphorus Improving-0.6 µg/L/yr6
See year-by-year chart →

Location

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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.

See full comparison →

Nearby Lakes in Beltrami County

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