Bass Lake
Otter Tail County, MinnesotaOligotrophic
Bass Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.
A TSI value of 40 puts Bass Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. 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. Among the 97 graded lakes in Otter Tail County, Bass Lake ranks 8 — in the top quartile locally.
Zebra mussel presence at Bass Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The state fisheries records do not list documented species for Bass Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Bass Lake — most use is by shoreline residents and their guests. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-30. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 16.9 ft down. Phosphorus level: 14.5 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.9 ft | A |
| Phosphorus | 14.5 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Invasive Species
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.14 m/yr | 5 |
| Phosphorus | → Stable | +0.1 µg/L/yr | 5 |
Location
County Ranking
Ranked #8 of 97 lakes in Otter Tail County
Nearby Lakes in Otter Tail County
More Minnesota Lake Rankings
State Parks Near Bass Lake
Other Grade A Lakes in Minnesota
Oligotrophic Lakes in Minnesota
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-09-30
Monitoring stations: 1