Big Traverse Bay Lake
Lake of the Woods County, MinnesotaMesotrophic
Big Traverse Bay Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.
Mesotrophic conditions dominate at Big Traverse Bay Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. 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. Big Traverse Bay Lake sits at rank 8 of 11 in Lake of the Woods County, in the lower half of the local distribution.
Zebra mussels have been documented at Big Traverse Bay Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The state fisheries records do not list documented species for Big Traverse Bay Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Public access is available — the lake is on the Minnesota PCA public-access list. 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 2025-08-28. Grade methodology: LakeGrade methodology.
Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 13.1 ft. Phosphorus level: 33.5 µg/L. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.1 ft | B |
| Phosphorus | 33.5 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Invasive Species
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.183 m/yr | 6 |
| Phosphorus | ↓ Declining | +1.29 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (6 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 1976-04-26 (1976) | 1996-05-19 (1996) |
| Ice-In | 1986-11-11 (1986) | 1988-11-17 (1988) |
Most recent ice-out: 1997-05-06
Location
County Ranking
Ranked #8 of 11 lakes in Lake of the Woods County
Nearby Lakes in Lake of the Woods County
More Minnesota Lake Rankings
State Parks Near Big Traverse Bay Lake
Other Grade B Lakes in Minnesota
Mesotrophic Lakes in Minnesota
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Big Traverse Bay Lake. 1 report on file.
- —Public Water Access Sites — Lake of the Woods (Main)Public Water Access Sites · MN DNR LakeFinder
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Ice data from Minnesota DNR Climate
Most recent sample: 2025-08-28
Monitoring stations: 1