Ashippun Lake
Ashippun Lake in Waukesha County, Wisconsin has a water quality grade of B (Good). 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 →
- Clarity
- 10 ft
- Typical in August
- 77°F
- Max depth
- 35 ft
- Area
- 94 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
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Ashippun Lake is a 94-acre mesotrophic lake in Waukesha County, Wisconsin with a maximum depth of 35 feet. Water quality is graded B based on 1 sampling years through 2026. 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. Grade methodology: LakeQuality methodology.
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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)
Good clarity, visible to about 10 ft. Phosphorus level: 13 µg/L. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | Not graded |
| Phosphorus | 13 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Ashippun Lake
Compare lakeside cabins, hotels, and vacation rentals near Ashippun 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 Ashippun Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
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.
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 a water-quality grade. LakeQuality grades Ashippun Lake B from EPA Water Quality Portal chemistry, 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
| Characteristic | Value |
|---|---|
| Maximum Depth | 35 ft |
| Surface Area | 94 acres |
| Public Access | Yes |
Lake Size & Watershed
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
Fish Species
Click a species to see every graded 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: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.218 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.46 µg/L/yr | 7 |
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.
County Ranking
Ranked #9 of 35 lakes in Waukesha County
Nearby Lakes With Higher Grades
Ashippun Lake holds Grade B. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Waukesha County
Frequently asked questions about Ashippun Lake
Where is Ashippun Lake?
- Ashippun Lake is a lake in Waukesha County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Ashippun Lake?
- Ashippun Lake in Waukesha County, Wisconsin has a water quality grade of B (Good). Water clarity: 10 ft visibility. Phosphorus: 13 µg/L. Maximum depth: 35 ft. Surface area: 94 acres.
Is Ashippun Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Ashippun Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
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 a water-quality grade. LakeQuality grades Ashippun Lake B from EPA Water Quality Portal chemistry, 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.
Explore Ashippun Lake across LakeQuality
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Moderate nutrients, good water quality
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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)
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