Where is Bear Trap Lake?

Bear Trap Lake is a lake in Polk County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.

What is the water temperature of Bear Trap Lake?

Bear Trap Lake typically sits around 70°F at the surface in September, from 28 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.

How deep is Bear Trap Lake?

Bear Trap Lake has a maximum depth of 25 feet. The lake covers 247 acres.

Can I fish at Bear Trap Lake?

Public access to Bear Trap Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.

Bear Trap Lake

Polk County, Wisconsin247 acresView map Directions

Wisconsin DNR publishes the water-quality measurements for Bear Trap Lake. Here is what has been measured.

Clarity

8.8 ft

Typical for Wisconsin

Secchi · sampled 2026

Phosphorus

24.9 µg/L

Typical for Wisconsin

Measured by Wisconsin DNR

Water temp

~70°F

Typical for Sep · EPA WQP

Max depth

25 ft

Bathymetric survey

Area

247 acres

Surface area

Type

Mesotrophic

Trophic class

Mesotrophic
Impaired · Cause unknown
2 aquatic invasives
25 ft max depth
Public access

See the measurements Directions Where to stay

Bear Trap Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 8.8 ft visibility. Phosphorus: 24.9 µg/L. Maximum depth: 25 ft. Surface area: 247 acres.

Wisconsin DNR lists Panfish as common on Bear Trap Lake. DNR survey details →

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Bear Trap Lake is a 247-acre mesotrophic lake in Polk County, Wisconsin with a maximum depth of 25 feet. Overall water quality is improving over recent sampling years. The lake supports 5 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available. Compared to the 54 other monitored lakes in Polk County, Bear Trap Lake ranks #32 for water quality.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-21. Methodology: how these readings are compared.

What Bear Trap Lake is good for

From access and monitoring records, not editorial picks.

Fishing5 species recorded

Swimming conditions

Readings only

Recreation 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. Bear Trap Lake is listed impaired under Clean Water Act §303(d) (IR 5R) for cause unknown. Check local advisories before you swim.

Whether Bear Trap Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.

Compare swimming lakes near St. Paul →

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Water quality measurements for Bear Trap Lake

These are the measurements Wisconsin DNR publishes for Bear Trap Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.

Moderate clarity, visible to about 8.8 ft. Phosphorus 24.9 µg/L. TSI 48.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	8.8ft	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	24.9µg/L	Fair GoodFairPoor
Chlorophyll-a (algae)		No reading The green pigment in algae — a direct measure of how much algae is in the water.
Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a.	48	Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic

Moderate nutrients, good water quality

Ask about Bear Trap Lake

Answers come straight from the public measurements and survey records on this page.

Water Temperature

Bear Trap Lake typically sits around 70°F at the surface in September. Summer average is about 75°F. Usually warmest in Jul (about 78°F) and coldest in Sep (about 70°F). These are typical values by month — not a live reading.

Jan

Feb

Mar

Apr

May

72°

Jun

78°

Jul

74°

Aug

70°

Sep

Oct

Nov

Dec

Column height runs from this lake’s coldest month (70°F) to its warmest (78°F).

Typical surface water temperature by month, from 28 field readings (2024–2025) via the EPA Water Quality Portal. See the full Bear Trap Lake water temperature breakdown →

DNR fisheries survey

Wisconsin DNR lists Panfish as common on Bear Trap Lake.

A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Bear Trap Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1991. 1 station on file (most recent sample 2025).

DNR Assessment

Good · Shallow Lowland lake

Trophic State Index 54 (eutrophic) · 5-year average

Fish Species (DNR-rated)

Panfish(Common)Largemouth Bass(Common)Walleye(Common)Musky(Present)Northern Pike(Present)

Contour map (PDF) →Full WI DNR LakePage →Water quality stations →

Lake Details

Max depth

25 ft

Surface area

247 acres

Public access

Yes

Listed by Wisconsin DNR

Stays via Stay22

Stays near Bear Trap Lake

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Top-rated places to stay near Bear Trap Lake

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Follow Bear Trap Lake’s readings

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Fish Species

Musky Panfish Largemouth Bass Northern Pike Walleye

Click a species to see every lake where it is documented.

Fishing Bear Trap 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.

Banded Mystery SnailChinese Mystery SnailCurly-Leaf PondweedZebra Mussel

Water Quality Trend: Improving

Based on 7 years of monitoring (2020–2026).

Water clarity
Improving
6 years
Phosphorus
Stable
+0.23 µg/L/yr7 years

See year-by-year chart →

EPA Impairment Status

Bear Trap Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).

Causes of impairment

Cause unknown

Designated uses not supporting: Recreation.

Source: EPA ATTAINS assessment unit WI10004970 · Official waterbody report

Regulated Pollution Sources Nearby

1 EPA-permitted facility operate within about 5 miles of Bear Trap Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.

Lake Wapogasset Bear Trap Lake S D
Garfield · 0.4 mi away · NPDES WI0060313
Recent violation

Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.

Nearby Lakes in Polk County

Wapogasset Lake6 ft clear · Eutrophic—View →Trident Lake—View →King Lake11.5 ft clear · Mesotrophic—View →South Twin Lake—View →North Twin LakeOligotrophic—View →Pike Lake—View →

Frequently asked questions about Bear Trap Lake

Where is Bear Trap Lake?: Bear Trap Lake is a lake in Polk County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Bear Trap Lake?: Bear Trap Lake in Polk County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 8.8 ft visibility. Phosphorus: 24.9 µg/L. Maximum depth: 25 ft. Surface area: 247 acres.
Is Bear Trap Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Bear Trap Lake is listed impaired under Clean Water Act §303(d) (IR 5R) for cause unknown. Check local advisories before you swim.
What is the water temperature of Bear Trap Lake?: Bear Trap Lake typically sits around 70°F at the surface in September, from 28 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Bear Trap Lake?: Bear Trap Lake has a maximum depth of 25 feet. The lake covers 247 acres.
What fish are in Bear Trap Lake?: Fish species found in Bear Trap Lake include Musky, Panfish, Largemouth Bass, Northern Pike, Walleye. Bear Trap Lake is located in Polk County, Wisconsin.
What did the DNR fisheries survey find at Bear Trap Lake?: Wisconsin DNR lists Panfish as common on Bear Trap Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Bear Trap Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Bear Trap Lake?: Public access to Bear Trap Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.

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State Parks Near Bear Trap Lake

Interstate Park

State Park · 13.1 mi

Straight Lake State Park

State Park · 20.1 mi

Willow River State Park

State Park · 24.4 mi

Other Lakes in Wisconsin

Upper Turtle Lake

Barron County · 4 ft

Little Sand Lake

Barron County · 4.8 ft

Big Trade Lake

Burnett County · 5 ft

Little Wood Lake

Burnett County · Measured

Poskin Lake

Barron County · 4 ft

Yellow Lake

Burnett County · 6 ft

Mesotrophic Lakes in Wisconsin

Big Moon Lake at Echo Lake Loon Lake Bass Lake

Where this data comes from

138 measurements from 1 monitoring station, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

Wisconsin Department of Natural ResourcesWIDNR_WQX138 samples · 2020–2026

Analytical methods

Phosphorus by Colorimetry

Monitoring station identifiers (1)

WIDNR_WQX-493122

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.