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

How deep is Green Lake?

Green Lake has a maximum depth of 37 feet. The lake covers 70 acres.

What fish are in Green Lake?

Fish species found in Green Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Green Lake is located in Washington County, Wisconsin.

Are there boat ramps on Green Lake?

Green Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Green Lake - South, Green Lake - North. Public access is listed as yes.

Can I fish at Green Lake?

Green Lake has 2 documented boat landings 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.

Green Lake

Washington County, Wisconsin70 acresView map Directions

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

Clarity

9 ft

Typical for Wisconsin

Secchi · sampled 2025

Phosphorus

16.6 µg/L

Typical for Wisconsin

Measured by Wisconsin DNR

Max depth

37 ft

Bathymetric survey

Area

70 acres

Surface area

Type

Mesotrophic

Trophic class

Trend

Improving

6 years of samples

Mesotrophic
Curly-Leaf Pondweed
37 ft max depth
Public access

See the measurements Directions Where to stay

Green Lake in Washington County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 9 ft visibility. Phosphorus: 16.6 µg/L. Maximum depth: 37 ft. Surface area: 70 acres.

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

Loading map…

Green Lake is a 70-acre mesotrophic lake in Washington County, Wisconsin with a maximum depth of 37 feet. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 2 public boat landings. Compared to the 12 other monitored lakes in Washington County, Green Lake ranks #3 for water quality.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-21. Methodology: how these readings are compared.

What Green Lake is good for

From access and monitoring records, not editorial picks.

Boat launch2 documented ramps
Fishing4 species recorded
Deep water37 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 Green 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 Milwaukee →

Get alerts for Green Lake →

Water quality measurements for Green Lake

These are the measurements Wisconsin DNR publishes for Green 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 9 ft. Phosphorus 16.6 µg/L. TSI 45.

Water quality readings
Measure	Reading	Where it sits
Water clarity (Secchi depth)	9ft	Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer.
Total phosphorus	16.6µg/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.	45	Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic

Moderate nutrients, good water quality

Ask about Green Lake

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

DNR fisheries survey

Wisconsin DNR lists Panfish as common on Green Lake.

A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Green Lake’s water-quality measurements separately, and the water-quality trend over 6 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 1986. 6 stations on file (most recent sample 2025).

DNR Assessment

Good · Deep Seepage lake

Trophic State Index 44 (mesotrophic) · 5-year average

Fish Species (DNR-rated)

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

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

Lake Details

Max depth

37 ft

Surface area

70 acres

Public access

Yes

Listed by Wisconsin DNR

Lake Size & Watershed

Watershed (drainage) area

0 sq mi

HydroLAKES / HydroSHEDS

Shoreline

1.6 mi

HydroLAKES / HydroSHEDS

Elevation

869 ft

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

Recreation & Access

Boat Landings

Yes

Public Access

Green Lake - SouthPublic
Green Lake - NorthPublic

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

Stays via Stay22

Stays near Green Lake

Compare lakeside cabins, hotels, and vacation rentals near Green Lake in Washington 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 Green 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 Green 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 Green 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 SnailCurly-Leaf PondweedEurasian Water-MilfoilHybrid Eurasian / Northern Water-MilfoilStarry Stonewort

Water Quality Trend: Improving

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

Water clarity
Improving
4 years
Phosphorus
Stable
-0.3 µg/L/yr6 years

See year-by-year chart →

Regulated Pollution Sources Nearby

2 EPA-permitted facilities operate within about 5 miles of Green Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.

West Bend City
West Bend · 4.4 mi away · NPDES WI0025763
MajorRecent violation
Golden E Dairy Llc
Farmington, Town Of · 2.4 mi away · NPDES WI0064602
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 Washington County

Erler Lake—View →Wallace Lake—View →Lake Twelve—View →Smith Lake4 ft clear—View →Lucas Lake—View →Silver Lake—View →

Frequently asked questions about Green Lake

Where is Green Lake?: Green Lake is a lake in Washington County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Green Lake?: Green Lake in Washington County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 9 ft visibility. Phosphorus: 16.6 µg/L. Maximum depth: 37 ft. Surface area: 70 acres.
Is Green Lake safe to swim in?: Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
How deep is Green Lake?: Green Lake has a maximum depth of 37 feet. The lake covers 70 acres.
What fish are in Green Lake?: Fish species found in Green Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Green Lake is located in Washington County, Wisconsin.
What did the DNR fisheries survey find at Green Lake?: Wisconsin DNR lists Panfish as common on Green Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Green Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Green Lake?: Green Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Green Lake - South, Green Lake - North. Public access is listed as yes.
Can I fish at Green Lake?: Green Lake has 2 documented boat landings 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 Green Lake across LakeQuality

Wisconsin Fishing Guide

Fish species and the cleanest lakes across Wisconsin

Washington County Fishing

Fish species and best lakes in Washington 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 Green Lake

Harrington Beach State Park

State Park · 15.4 mi

Kohler-Andrae State Park

State Park · 23.7 mi

Other Lakes in Wisconsin

Sandhill Lake

Ozaukee County · 7.5 ft

Forest Lake

Fond du Lac County · 14 ft

Auburn Lake

Fond du Lac County · 7.6 ft

Random Lake

Sheboygan County · 4.5 ft

Lake Ellen

Sheboygan County · 9 ft

Kettle Moraine Lake

Fond du Lac County · 11 ft

Mesotrophic Lakes in Wisconsin

Sandhill Lake Unnamed Lake Forest Lake Moldenhauer Lake

Where this data comes from

99 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

Wisconsin Department of Natural ResourcesWIDNR_WQX99 samples · 2020–2025

Analytical methods

Phosphorus by Colorimetry

Monitoring station identifiers (1)

WIDNR_WQX-673208

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

Regulated discharger data from EPA ECHO (ICIS-NPDES)

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