Johnson Lake
Beltrami County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Johnson Lake. Here is what has been measured.
- Mesotrophic
Johnson Lake in Beltrami County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 7.5 ft visibility. Phosphorus: 23.5 µg/L. Chlorophyll-a (algae): 6.4 µg/L.
Johnson Lake is a mesotrophic lake in Beltrami County, Minnesota. Overall water quality is improving over recent sampling years. Compared to the 84 other monitored lakes in Beltrami County, Johnson Lake ranks #38 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-17. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Johnson Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Johnson Lake
These are the measurements Minnesota PCA publishes for Johnson Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 7.5 ft. Phosphorus 23.5 µg/L. Chlorophyll-a 6.4 µg/L. TSI 49.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 7.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 23.5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 6.4µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 49 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Johnson Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Johnson Lake typically sits around 62°F at the surface in September. Summer average is about 73°F. Usually warmest in Jul (about 75°F) and coldest in Jan (about 32°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (32°F) to its warmest (75°F).
Typical surface water temperature by month, from 70 field readings (2010–2025) via the EPA Water Quality Portal. See the full Johnson Lake water temperature breakdown →
Stays via Stay22
Stays near Johnson Lake
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Fishing Johnson Lake
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Improving6 years
Phosphorus
Improving-0.71 µg/L/yr6 years
Chlorophyll-a
Improving-0.89 µg/L/yr6 years
Nearby Lakes in Beltrami County
Frequently asked questions about Johnson Lake
Where is Johnson Lake?
- Johnson Lake is a lake in Beltrami County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Johnson Lake?
- Johnson Lake in Beltrami County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 7.5 ft visibility. Phosphorus: 23.5 µg/L. Chlorophyll-a (algae): 6.4 µg/L.
Is Johnson Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Johnson Lake?
- Johnson Lake typically sits around 62°F at the surface in September, from 70 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
Explore Johnson Lake across LakeQuality
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Where this data comes from
98 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Red Lake DNR
REDLAKE_WQX98 samples · 2020–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.