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

What is the water temperature of Apple Lake?

Apple Lake typically sits around 65°F at the surface in September, from 9 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.

How deep is Apple Lake?

Apple Lake has a maximum depth of 32 feet. The lake covers 110 acres.

What fish are in Apple Lake?

Fish species found in Apple Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Apple Lake is located in St. Croix County, Wisconsin.

Can I fish at Apple Lake?

Public access to Apple 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.

Apple Lake

St. Croix County, Wisconsin110 acresView map Directions

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

Clarity

2.5 ft

Murkier than most

Secchi · sampled 2026

Phosphorus

84.9 µg/L

More phosphorus than most

Measured by Wisconsin DNR

Water temp

~65°F

Typical for Sep · EPA WQP

Max depth

32 ft

Bathymetric survey

Area

110 acres

Surface area

Type

Eutrophic

Trophic class

Eutrophic
Impaired · Nutrients (phosphorus, nitrogen)
Curly-Leaf Pondweed
32 ft max depth
Public access

See the measurements Directions Where to stay

Apple Lake in St. Croix County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 2.5 ft visibility. Phosphorus: 84.9 µg/L. Maximum depth: 32 ft. Surface area: 110 acres.

Wisconsin DNR rates Panfish and Largemouth Bass as abundant on Apple Lake. DNR survey details →

Loading map…

Apple Lake is a 110-acre productive, nutrient-rich eutrophic lake in St. Croix County, Wisconsin with a maximum depth of 32 feet. Water clarity is declining over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available. Compared to the 4 other monitored lakes in St. Croix County, Apple Lake ranks #4 for water quality.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-04-22. Methodology: how these readings are compared.

What Apple Lake is good for

From access and monitoring records, not editorial picks.

Fishing4 species recorded
Deep water32 ft surveyed max depth

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. Apple Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.

Whether Apple 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 →

Get alerts for Apple Lake →

Water quality measurements for Apple Lake

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

Very murky, less than 2.5 ft of visibility. Phosphorus 84.9 µg/L. TSI 66.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	2.5ft	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	84.9µg/L	Poor 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.	66	Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic

High nutrients, frequent algae, reduced clarity

Ask about Apple Lake

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

Water Temperature

Apple Lake typically sits around 65°F at the surface in September. Summer average is about 78°F. Usually warmest in Jul (about 78°F) and coldest in Sep (about 65°F). These are typical values by month — not a live reading.

Jan

Feb

Mar

Apr

May

Jun

78°

Jul

77°

Aug

65°

Sep

Oct

Nov

Dec

Column height runs from this lake’s coldest month (65°F) to its warmest (78°F).

Typical surface water temperature by month, from 9 field readings (2024–2025) via the EPA Water Quality Portal. See the full Apple Lake water temperature breakdown →

DNR fisheries survey

Wisconsin DNR rates Panfish and Largemouth Bass as abundant on Apple Lake.

A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Apple Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. 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. 2 stations on file (most recent sample 2025).

DNR Assessment

Poor · Deep Seepage lake

Trophic State Index 69 (eutrophic) · 5-year average

Fish Species (DNR-rated)

Panfish(Abundant)Largemouth Bass(Abundant)Northern Pike(Present)Walleye(Present)

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

DNR Reports & Resources

Wisconsin DNR Fisheries scientists publish multi-year survey reports for Apple Lake covering fish populations, stocking, water quality, and management. 1 report on file.

These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).

2024
Apple Lake spring survey, 2024
Fisheries Survey · WI DNR · 2024 (PDF)

Lake Details

Max depth

32 ft

Surface area

110 acres

Public access

Yes

Listed by Wisconsin DNR

Lake Size & Watershed

Watershed (drainage) area

9 sq mi

HydroLAKES / HydroSHEDS

Shoreline

3.2 mi

HydroLAKES / HydroSHEDS

Elevation

938 ft

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

Stays via Stay22

Stays near Apple Lake

Compare lakeside cabins, hotels, and vacation rentals near Apple Lake in St. Croix 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Apple Lake are listed below.

Top-rated places to stay near Apple Lake

Prices for Oct 9–11, 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 Apple Lake’s readings

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

Or email

Fish Species

Panfish Largemouth Bass Northern Pike Walleye

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

Fishing Apple 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.

Curly-Leaf Pondweed

Water Quality Trend: Stable

Based on 6 years of monitoring (2020–2025).

Water clarity
Worsening
5 years
Phosphorus
Improving
-26.1 µg/L/yr6 years

See year-by-year chart →

EPA Impairment Status

Apple Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Nutrients (phosphorus, nitrogen)

Designated uses not supporting: Aquatic life, Recreation.

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit WI10005074 · Official waterbody report

Nearby Lakes in St. Croix County

Riverdale Flowage—View →Turtle Lake—View →Hatfield Lake—View →Pine Lake—View →Bass Lake10 ft clear · Mesotrophic—View →Oak Ridge Lake—View →

Frequently asked questions about Apple Lake

Where is Apple Lake?: Apple Lake is a lake in St. Croix County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Apple Lake?: Apple Lake in St. Croix County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 2.5 ft visibility. Phosphorus: 84.9 µg/L. Maximum depth: 32 ft. Surface area: 110 acres.
Is Apple Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Apple Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Apple Lake?: Apple Lake typically sits around 65°F at the surface in September, from 9 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Apple Lake?: Apple Lake has a maximum depth of 32 feet. The lake covers 110 acres.
What fish are in Apple Lake?: Fish species found in Apple Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Apple Lake is located in St. Croix County, Wisconsin.
What did the DNR fisheries survey find at Apple Lake?: Wisconsin DNR rates Panfish and Largemouth Bass as abundant on Apple Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Apple Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Apple Lake?: Public access to Apple 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.

Explore Apple Lake across LakeQuality

Wisconsin Fishing Guide

Fish species and the cleanest lakes across Wisconsin

St. Croix County Fishing

Fish species and best lakes in St. Croix 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

St. Croix Watershed

Lakes in the St. Croix Watershed, ranked by water quality

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 Apple Lake

Willow River State Park

State Park · 12.1 mi

Interstate Park

State Park · 14.1 mi

Other Lakes in Wisconsin

Cedar Lake

Polk County · 6.1 ft

Mud Lake

Polk County · 2 ft

Black Brook Flowage Lake

Polk County · 10.5 ft

Mud Lake

Polk County · 5.2 ft

Apple River Flowage Lake

Polk County · 5.9 ft

Omer Lake

Polk County · 5 ft

Eutrophic Lakes in Wisconsin

Cedar Lake Mud Lake Lotus Lake Wapogasset Lake

Where this data comes from

46 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_WQX46 samples · 2020–2026

Analytical methods

Phosphorus by Colorimetry

Monitoring station identifiers (1)

WIDNR_WQX-563056

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.