Pewaukee Lake
Waukesha County, Wisconsin2,437 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Pewaukee Lake. Here is what has been measured.
- Mesotrophic
- 4 aquatic invasives
- 45 ft max depth
- Public access
Pewaukee Lake in Waukesha County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 7.5 ft visibility. Phosphorus: 19.9 µg/L. Maximum depth: 45 ft. Surface area: 2437 acres.
Wisconsin DNR lists Musky as common on Pewaukee Lake. DNR survey details →
Pewaukee Lake is a 2,437-acre mesotrophic lake in Waukesha County, Wisconsin with a maximum depth of 45 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 with 1 public boat landing. Compared to the 34 other monitored lakes in Waukesha County, Pewaukee Lake ranks #14 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-05-21. Methodology: how these readings are compared.
Pewaukee Lake covers about 2,400 acres in Waukesha County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Pewaukee Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Pewaukee Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Fishing5 species recorded
- Deep water45 ft surveyed max depth
- Big water2,437 acres
Swimming conditions
Readings onlyLow 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 Pewaukee 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.
Water quality measurements for Pewaukee Lake
These are the measurements Wisconsin DNR publishes for Pewaukee 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 7.5 ft. Phosphorus 19.9 µg/L. TSI 48.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 7.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 19.9µg/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 Pewaukee Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Pewaukee Lake typically sits around 74°F at the surface in September. Summer average is about 76°F. Usually warmest in Aug (about 76°F) and coldest in Nov (about 40°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (40°F) to its warmest (76°F).
Typical surface water temperature by month, from 12 field readings (2024–2025) via the EPA Water Quality Portal. See the full Pewaukee Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Pewaukee Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (80,168 cells/mL) on June 27, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR lists Musky as common on Pewaukee Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Pewaukee 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. 4 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
45 ft
Surface area
2,437 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
24 sq mi
HydroLAKES / HydroSHEDS
Shoreline
12.7 mi
HydroLAKES / HydroSHEDS
Elevation
850 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Pewaukee 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 Pewaukee Lake
Compare lakeside cabins, hotels, and vacation rentals near Pewaukee Lake in Waukesha 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 Pewaukee 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 Pewaukee Lake’s readings
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Fish Species
Click a species to see every lake where it is documented.
Fishing Pewaukee 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 (2020–2025).
Water clarity
Improving6 years
Phosphorus
Improving-1.11 µg/L/yr5 years
Reservoir Info (USACE NID)
Pewaukee Lake is a man-made reservoir impounded by the Pewaukee (completed 1842), built primarily for recreation on the PEWAUKEE; gravity-type dam, 14 ft tall and 800 ft long.
- Surface area
- 2,493 ac
- Normal storage
- 15,000 ac-ft
- Max storage
- 36,900 ac-ft
- Drainage area
- 27.6 sq mi
- Hazard class
- High
- Owner
- Village Of Pewaukee
Source: USACE National Inventory of Dams, NID ID WI00336 · Operator website
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Pewaukee Lake under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Sussex Wastewater Treatment FacilitySussex · 4.5 mi away · NPDES WI0020559MajorRecent 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 Waukesha County
Frequently asked questions about Pewaukee Lake
Where is Pewaukee Lake?
- Pewaukee Lake is a lake in Waukesha County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Pewaukee Lake?
- Pewaukee Lake in Waukesha County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 7.5 ft visibility. Phosphorus: 19.9 µg/L. Maximum depth: 45 ft. Surface area: 2437 acres.
Is Pewaukee 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 Pewaukee Lake?
- Pewaukee Lake typically sits around 74°F at the surface in September, from 12 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Pewaukee Lake?
- Pewaukee Lake has a maximum depth of 45 feet. The lake covers 2437 acres.
What fish are in Pewaukee Lake?
- Fish species found in Pewaukee Lake include Musky, Panfish, Largemouth Bass, Northern Pike, Walleye. Pewaukee Lake is located in Waukesha County, Wisconsin.
What did the DNR fisheries survey find at Pewaukee Lake?
- Wisconsin DNR lists Musky as common on Pewaukee Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Pewaukee 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.
Does Pewaukee Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Pewaukee Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (80,168 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Pewaukee Lake?
- Pewaukee Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Pewaukee Lake. Public access is listed as yes.
Can I fish at Pewaukee Lake?
- Pewaukee 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 Pewaukee Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Waukesha County
Species activity outlook by water temperature and season
Where to stay at Wisconsin's top lakes, each with its readings
Wisconsin's cleanest lakes, ranked on agency measurements
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Mesotrophic Lakes in Wisconsin
Compare Pewaukee Lake With Nearby Lakes
Where this data comes from
104 measurements from 2 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX104 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (2)
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