Loon Lake
Loon Lake in Becker County, Minnesota has a water quality grade of A (Excellent). Water clarity: 7.4 ft visibility. Phosphorus: 14.5 µg/L. Chlorophyll-a (algae): 2.5 µg/L.
- Clarity
- 7.4 ft
- Typical in August
- 74°F
- Max depth
- ~47 ft est.
- Type
- Mesotrophic
- Trend
- ↑ Improving
Next lake in Becker County
Loon Lake is a mesotrophic lake in Becker County, Minnesota with an estimated average depth of about 47 feet. Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Compared to the 83 other monitored lakes in Becker County, Loon Lake ranks #30 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-11. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Moderate clarity, visible to about 7.4 ft. Phosphorus level: 14.5 µg/L. Chlorophyll-a: 2.5 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.4 ft | Not graded |
| Phosphorus | 14.5 µg/L | Good |
| Chlorophyll-a (Algae) | 2.5 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Loon Lake
Compare lakeside cabins, hotels, and vacation rentals near Loon Lake in Becker County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
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Water Temperature
Loon Lake typically sits around 74°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 78°F) and coldest in Sep (about 65°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 23 field readings (2025–2025) via the EPA Water Quality Portal. See the full Loon Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~47 ft est. |
| Average Depth | ~13 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Loon Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Loon Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.104 m/yr | 2 |
| Phosphorus | ↑ Improving | -0.8 µg/L/yr | 2 |
| Chlorophyll-a | ↑ Improving | -0.36 µg/L/yr | 2 |
County Ranking
Ranked #30 of 84 lakes in Becker County
Nearby Lakes in Becker County
Frequently asked questions about Loon Lake
What is the water quality grade for Loon Lake?
- Loon Lake in Becker County, Minnesota has a water quality grade of A (Excellent). Water clarity: 7.4 ft visibility. Phosphorus: 14.5 µg/L. Chlorophyll-a (algae): 2.5 µg/L.
Is Loon Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Loon Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Loon Lake?
- Loon Lake typically sits around 74°F at the surface in August, from 23 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
How deep is Loon Lake?
- No published bathymetric survey covers Loon Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 47 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
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Where this data comes from
48 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA48 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder