Spear Lake
Spear Lake in Becker County, Minnesota has a water quality grade of C (Fair). Water clarity: 10.3 ft visibility. Phosphorus: 28 µg/L. Chlorophyll-a (algae): 4.5 µg/L.
- Clarity
- 10.3 ft
- Typical in August
- 75°F
- Max depth
- ~45 ft est.
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- No
Next lake in Becker County
Spear Lake is a mesotrophic lake in Becker County, Minnesota with an estimated average depth of about 45 feet. Water quality is graded C based on 2 sampling years through 2025. Limited fish-species data available. No public access — the lake is private or restricted. Compared to the 83 other monitored lakes in Becker County, Spear Lake ranks #61 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 onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Good clarity, visible to about 10.3 ft. Phosphorus level: 28 µg/L. Chlorophyll-a: 4.5 µg/L. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.3 ft | Not graded |
| Phosphorus | 28 µg/L | Fair |
| Chlorophyll-a (Algae) | 4.5 µg/L | Good |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Spear Lake
Compare lakeside cabins, hotels, and vacation rentals near Spear 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.
Top-rated places to stay near Spear Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Spear Lake typically sits around 75°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 77°F) and coldest in Sep (about 66°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 32 field readings (2025–2025) via the EPA Water Quality Portal. See the full Spear Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~45 ft est. |
| Average Depth | ~8 ft est. |
| Public Access | No |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Minnesota has not published bathymetry for Spear 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 Spear Lake
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.047 m/yr | 5 |
| Phosphorus | → Stable | -0.14 µg/L/yr | 6 |
| Chlorophyll-a | → Stable | -0.05 µg/L/yr | 6 |
County Ranking
Ranked #61 of 84 lakes in Becker County
Nearby Lakes With Higher Grades
Spear Lake holds Grade C. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Becker County
Frequently asked questions about Spear Lake
What is the water quality grade for Spear Lake?
- Spear Lake in Becker County, Minnesota has a water quality grade of C (Fair). Water clarity: 10.3 ft visibility. Phosphorus: 28 µg/L. Chlorophyll-a (algae): 4.5 µg/L.
Is Spear Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Spear Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 4.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Spear Lake?
- Spear Lake typically sits around 75°F at the surface in August, from 32 EPA Water Quality Portal field readings (2025–2025). That is a typical value for the month, not a live reading.
How deep is Spear Lake?
- No published bathymetric survey covers Spear Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 45 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Spear Lake across LakeGrade
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Where this data comes from
46 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
MNPCA46 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