Big Traverse Bay Lake
Lake of the Woods County, MinnesotaView mapDirections
Minnesota PCA publishes the water-quality measurements for Big Traverse Bay Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- 2 aquatic invasives
- Public access
Big Traverse Bay Lake in Lake of the Woods County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4 ft visibility. Phosphorus: 33.5 µg/L. Chlorophyll-a (algae): 13.7 µg/L.
Big Traverse Bay Lake is a productive, nutrient-rich eutrophic lake in Lake of the Woods County, Minnesota. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 9 other monitored lakes in Lake of the Woods County, Big Traverse Bay Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-28. Methodology: how these readings are compared.
What Big Traverse Bay Lake is good for
From access and monitoring records, not editorial picks.
- Ice seasonIce-out around May 5
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Big Traverse Bay Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Big Traverse Bay Lake is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Big Traverse Bay Lake
These are the measurements Minnesota PCA publishes for Big Traverse Bay Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4 ft. Phosphorus 33.5 µg/L. Chlorophyll-a 13.7 µg/L. TSI 56.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 33.5µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 13.7µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 56 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Big Traverse Bay Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Big Traverse Bay Lake typically sits around 57°F at the surface in October. Summer average is about 71°F. Usually warmest in Jul (about 74°F) and coldest in May (about 41°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (41°F) to its warmest (74°F).
Typical surface water temperature by month, from 30 field readings (2010–2025) via the EPA Water Quality Portal. See the full Big Traverse Bay Lake water temperature breakdown →
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.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Public Water Access Sites — Lake of the Woods (Main)Public Water Access Sites · MN DNR LakeFinder
Stays via Stay22
Stays near Big Traverse Bay Lake
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Top-rated places to stay near Big Traverse Bay Lake
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Fishing Big Traverse Bay Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: Worsening
Based on 6 years of monitoring (2020–2025).
Water clarity
Worsening6 years
Phosphorus
Worsening+1.29 µg/L/yr5 years
Chlorophyll-a
Worsening+7.73 µg/L/yr5 years
Ice season
Typical ice-out
May 5
Earliest Apr 26, 1976 · Latest May 19, 1996
Most recent ice-out
May 6
1997
6 observations · Minnesota PCA ice records
EPA Impairment Status
Big Traverse Bay Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN39-0002-01 · Official waterbody report
Nearby Lakes in Lake of the Woods County
Frequently asked questions about Big Traverse Bay Lake
Where is Big Traverse Bay Lake?
- Big Traverse Bay Lake is a lake in Lake of the Woods County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Big Traverse Bay Lake?
- Big Traverse Bay Lake in Lake of the Woods County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4 ft visibility. Phosphorus: 33.5 µg/L. Chlorophyll-a (algae): 13.7 µg/L.
Is Big Traverse Bay Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Big Traverse Bay Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Big Traverse Bay Lake?
- Big Traverse Bay Lake typically sits around 57°F at the surface in October, from 30 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
When does Big Traverse Bay Lake thaw?
- Big Traverse Bay Lake typically has ice-out around May 5.
Can I fish at Big Traverse Bay Lake?
- Public access to Big Traverse Bay Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Big Traverse Bay Lake across LakeQuality
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Where this data comes from
42 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Red Lake DNR
REDLAKE_WQX42 samples · 2020–2025
Analytical methods
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Turbidity by Nephelometry
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Ice data from Minnesota DNR Climate