Green Lake
Green Lake in Washington County, Wisconsin has a water quality grade of B (Good). 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 →
- Clarity
- 9 ft
- Max depth
- 37 ft
- Area
- 70 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Washington County
Swipe left or right on this bar to open the next or previous lake.
Green Lake is a 70-acre mesotrophic lake in Washington County, Wisconsin with a maximum depth of 37 feet. Water quality is graded B based on 1 sampling years through 2025. 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. Grade methodology: LakeQuality methodology.
Watch Green Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Moderate clarity, visible to about 9 ft. Phosphorus level: 16.6 µg/L. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | Not graded |
| Phosphorus | 16.6 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay 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
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 →
Wisconsin DNR lists Panfish as common on Green Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Green Lake B from EPA Water Quality Portal chemistry, 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).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 37 ft |
| Surface Area | 70 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & 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
Fish Species
Click a species to see every graded 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.
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.325 m/yr | 4 |
| Phosphorus | → Stable | -0.3 µg/L/yr | 6 |
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 CityWest Bend · 4.4 mi away · NPDES WI0025763MajorRecent violation
- Golden E Dairy LlcFarmington, Town Of · 2.4 mi away · NPDES WI0064602Recent 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.
County Ranking
Ranked #3 of 13 lakes in Washington County
Nearby Lakes in Washington County
Frequently asked questions about Green Lake
Where is Green Lake?
- Green Lake is a lake in Washington County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Green Lake?
- Green Lake in Washington County, Wisconsin has a water quality grade of B (Good). 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?
- Good for swimming, clear water with low algae levels. Green Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
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 a water-quality grade. LakeQuality grades Green Lake B from EPA Water Quality Portal chemistry, 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.
Explore Green Lake across LakeQuality
Fish species and top-graded lakes across Wisconsin
Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its grade
Lakes in the St. Croix Watershed, ranked by water quality
Moderate nutrients, good water quality
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
State Parks Near Green Lake
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
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 Resources
WIDNR_WQX99 samples · 2020–2025
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated 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