Ashippun Lake
Waukesha County, Wisconsin94 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Ashippun Lake. Here is what has been measured.
- Mesotrophic
- 3 aquatic invasives
- 35 ft max depth
- Public access
Ashippun Lake in Waukesha County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 10 ft visibility. Phosphorus: 13 µg/L. Maximum depth: 35 ft. Surface area: 94 acres.
Wisconsin DNR lists Panfish as common on Ashippun Lake. DNR survey details →
Ashippun Lake is a 94-acre mesotrophic lake in Waukesha County, Wisconsin with a maximum depth of 35 feet. Overall water quality is declining over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 34 other monitored lakes in Waukesha County, Ashippun Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-20. Methodology: how these readings are compared.
What Ashippun Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10 ft of visibility
- Boat launch1 documented ramp
- Fishing4 species recorded
- Deep water35 ft surveyed max depth
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 Ashippun 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 Ashippun Lake
These are the measurements Wisconsin DNR publishes for Ashippun Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 10 ft. Phosphorus 13 µg/L. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 13µg/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. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Ashippun Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Ashippun Lake typically sits around 77°F at the surface in August. Summer average is about 78°F. Usually warmest in Jun (about 79°F) and coldest in Mar (about 47°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (47°F) to its warmest (79°F).
Typical surface water temperature by month, from 17 field readings (2024–2025) via the EPA Water Quality Portal. See the full Ashippun Lake water temperature breakdown →
Wisconsin DNR lists Panfish as common on Ashippun Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Ashippun 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 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
35 ft
Surface area
94 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
1 sq mi
HydroLAKES / HydroSHEDS
Shoreline
1.4 mi
HydroLAKES / HydroSHEDS
Elevation
869 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Ashippun LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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Stays near Ashippun Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Ashippun 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: Worsening
Based on 7 years of monitoring (2020–2026).
Water clarity
Worsening6 years
Phosphorus
Worsening+0.46 µg/L/yr7 years
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Ashippun Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Ashippun Sanitary District WwtfAshippun · 4.4 mi away · NPDES WI0031381Recent 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 Ashippun Lake
Where is Ashippun Lake?
- Ashippun 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 Ashippun Lake?
- Ashippun Lake in Waukesha County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 10 ft visibility. Phosphorus: 13 µg/L. Maximum depth: 35 ft. Surface area: 94 acres.
Is Ashippun 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 Ashippun Lake?
- Ashippun Lake typically sits around 77°F at the surface in August, from 17 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Ashippun Lake?
- Ashippun Lake has a maximum depth of 35 feet. The lake covers 94 acres.
What fish are in Ashippun Lake?
- Fish species found in Ashippun Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Ashippun Lake is located in Waukesha County, Wisconsin.
What did the DNR fisheries survey find at Ashippun Lake?
- Wisconsin DNR lists Panfish as common on Ashippun Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Ashippun 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 Ashippun Lake?
- Ashippun Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Ashippun Lake. Public access is listed as yes.
Can I fish at Ashippun Lake?
- Ashippun 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 Ashippun Lake across LakeQuality
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Where this data comes from
44 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 Resources
WIDNR_WQX44 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (1)
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