Spear Lake
Becker County, MinnesotaMesotrophic
Spear Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. 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. Spear Lake sits at rank 69 of 93 in Becker County, in the lower half of the local distribution.
Spear Lake has no invasive species recorded in Minnesota state databases as of 2020, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Spear Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Spear Lake — most use is by shoreline residents and their guests. 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 2020-09-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 9.8 ft. Phosphorus level: 30.5 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.8 ft | C |
| Phosphorus | 30.5 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.025 m/yr | 4 |
| Phosphorus | ↑ Improving | -1.4 µg/L/yr | 5 |
Location
County Ranking
Ranked #69 of 93 lakes in Becker County
Cleaner Lakes Within 30 Miles
Spear Lake holds Grade C. 4 nearby lakes hold higher grades.
- APearl LakeBecker County · mi · Two grade letters higher (C → A)
- AFox LakeBecker County · mi · Two grade letters higher (C → A)
- BLoon LakeBecker County · mi · Higher grade (C → B)
- BMunson LakeBecker County · mi · Higher grade (C → B)
Nearby Lakes in Becker County
More Minnesota Lake Rankings
State Parks Near Spear Lake
Other Grade C 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: 2020-09-22
Monitoring stations: 1