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

What is the water temperature of Tree Lake?

Tree Lake typically sits around 69°F at the surface in September, from 62 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.

How deep is Tree Lake?

Tree Lake has a maximum depth of 33 feet. The lake covers 73 acres.

What fish are in Tree Lake?

Fish species found in Tree Lake include Panfish, Largemouth Bass, Northern Pike. Tree Lake is located in Portage County, Wisconsin.

Are there boat ramps on Tree Lake?

Tree Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Tree Lake. Public access is listed as yes.

Can I fish at Tree Lake?

Tree Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. 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.

Tree Lake

Portage County, Wisconsin73 acresView map Directions

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

Clarity

7.4 ft

Typical for Wisconsin

Secchi · sampled 2026

Phosphorus

20.1 µg/L

Typical for Wisconsin

Measured by Wisconsin DNR

Water temp

~69°F

Typical for Sep · EPA WQP

Max depth

33 ft

Bathymetric survey

Area

73 acres

Surface area

Type

Mesotrophic

Trophic class

Mesotrophic
Curly-Leaf Pondweed
33 ft max depth
Public access

See the measurements Directions Where to stay

Tree Lake in Portage County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 7.4 ft visibility. Phosphorus: 20.1 µg/L. Maximum depth: 33 ft. Surface area: 73 acres.

Wisconsin DNR lists Largemouth Bass as common on Tree Lake. DNR survey details →

Loading map…

Tree Lake is a 73-acre mesotrophic lake in Portage County, Wisconsin with a maximum depth of 33 feet. Overall water quality is declining over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 13 other monitored lakes in Portage County, Tree Lake ranks #4 for water quality.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-22. Methodology: how these readings are compared.

What Tree Lake is good for

From access and monitoring records, not editorial picks.

Boat launch1 documented ramp
Fishing3 species recorded
Deep water33 ft surveyed max depth

Swimming conditions

Readings only

Low algae

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. Check local advisories before you swim.

Whether Tree 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 Stevens Point →

Get alerts for Tree Lake →

Water quality measurements for Tree Lake

These are the measurements Wisconsin DNR publishes for Tree 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 7.4 ft. Phosphorus 20.1 µg/L. TSI 48.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	7.4ft	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	20.1µg/L	Good 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 Tree Lake

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

Water Temperature

Tree Lake typically sits around 69°F at the surface in September. Summer average is about 76°F. Usually warmest in Jul (about 79°F) and coldest in Feb (about 34°F). These are typical values by month — not a live reading.

Jan

34°

Feb

Mar

53°

Apr

65°

May

75°

Jun

79°

Jul

75°

Aug

69°

Sep

Oct

Nov

Dec

Column height runs from this lake’s coldest month (34°F) to its warmest (79°F).

Typical surface water temperature by month, from 62 field readings (2024–2026) via the EPA Water Quality Portal. See the full Tree Lake water temperature breakdown →

DNR fisheries survey

Wisconsin DNR lists Largemouth Bass as common on Tree Lake.

A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Tree Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is declining. 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 1990. 1 station on file (most recent sample 2026).

DNR Assessment

Fair · Deep Lowland lake

Trophic State Index 55 (eutrophic) · 5-year average

Fish Species (DNR-rated)

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

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

Lake Details

Max depth

33 ft

Surface area

73 acres

Public access

Yes

Listed by Wisconsin DNR

Lake Size & Watershed

Watershed (drainage) area

0 sq mi

HydroLAKES / HydroSHEDS

Shoreline

1.3 mi

HydroLAKES / HydroSHEDS

Elevation

1,152 ft

Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).

Recreation & Access

Boat Landings

Yes

Public Access

Tree LakePublic

Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps

Stays via Stay22

Stays near Tree Lake

Compare lakeside cabins, hotels, and vacation rentals near Tree Lake in Portage County, Wisconsin — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.

Top-rated places to stay near Tree Lake

Prices for Oct 16–18, 4 adults. Change dates on the map below.

Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.

Planning a whole trip? See where to stay at Wisconsin’s top lakes →

Follow Tree Lake’s readings

Email me when new measurements post for this lake. Updates stay free.

Or email

Fish Species

Panfish Largemouth Bass Northern Pike

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

Fishing Tree 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 Pondweed

Water Quality Trend: Worsening

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

Water clarity
Worsening
7 years
Phosphorus
Worsening
+6.26 µg/L/yr4 years

See year-by-year chart →

Nearby Lakes in Portage County

Lions Lake—View →Culvert on Lake HelenEutrophic—View →Lake Helen8 ft clear · Mesotrophic—View →Collins Lake6.5 ft clear · Mesotrophic—View →Sunset Lake13.3 ft clear · Mesotrophic—View →Hintz Lake—View →

Frequently asked questions about Tree Lake

Where is Tree Lake?: Tree Lake is a lake in Portage County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Tree Lake?: Tree Lake in Portage County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 7.4 ft visibility. Phosphorus: 20.1 µg/L. Maximum depth: 33 ft. Surface area: 73 acres.
Is Tree Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Tree Lake?: Tree Lake typically sits around 69°F at the surface in September, from 62 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Tree Lake?: Tree Lake has a maximum depth of 33 feet. The lake covers 73 acres.
What fish are in Tree Lake?: Fish species found in Tree Lake include Panfish, Largemouth Bass, Northern Pike. Tree Lake is located in Portage County, Wisconsin.
What did the DNR fisheries survey find at Tree Lake?: Wisconsin DNR lists Largemouth Bass as common on Tree Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Tree Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Tree Lake?: Tree Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Tree Lake. Public access is listed as yes.
Can I fish at Tree Lake?: Tree Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. 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.

Explore Tree Lake across LakeQuality

Wisconsin Fishing Guide

Fish species and the cleanest lakes across Wisconsin

Portage County Fishing

Fish species and best lakes in Portage County

Lake Fishing Forecast

Species activity outlook by water temperature and season

Wisconsin Lake Trips

Where to stay at Wisconsin's top lakes, each with its readings

The State of Wisconsin's Lakes

Wisconsin's cleanest lakes, ranked on agency measurements

More lakes in Wisconsin

Clearest lakes in Wisconsin

Ranked by Secchi water clarity

All Wisconsin lakes

Every Wisconsin lake with its Wisconsin DNR measurements

Lake water quality by country

Official ratings and named-lake measurements

State Parks Near Tree Lake

Hartman Creek State Park

State Park · 24.3 mi

Other Lakes in Wisconsin

Big Bass Lake

Marathon County · 6 ft

Nutrient Sampling Point Lake

Waupaca County · 14.5 ft

North Lake

Waupaca County · 12.5 ft

Hatch Lake

Waupaca County · 8.4 ft

Iola Lake

Waupaca County · 10 ft

Silver Lake

Waupaca County · 7 ft

Mesotrophic Lakes in Wisconsin

Big Bass Lake Nutrient Sampling Point Lake North Lake Hatch Lake

Where this data comes from

40 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_WQX40 samples · 2020–2026

Analytical methods

Phosphorus by Colorimetry

Monitoring station identifiers (1)

WIDNR_WQX-503135

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

Lake size & watershed from HydroLAKES (HydroSHEDS)

Fish and recreation data from Wisconsin DNR Lakes

Named boat-access points from the USGS National Boat Ramps inventory