Lower Nashotah Lake
Lower Nashotah Lake in Waukesha County, Wisconsin has a water quality grade of B (Good). Water clarity: 9 ft visibility. Phosphorus: 11.3 µg/L. Maximum depth: 43 ft. Surface area: 93 acres.
Wisconsin DNR lists Panfish as common on Lower Nashotah Lake. DNR survey details →
- Clarity
- 9 ft
- Typical in August
- 76°F
- Max depth
- 43 ft
- Area
- 93 acres
- Type
- Mesotrophic
- Trend
- → Stable
- Public access
- Yes
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Lower Nashotah Lake is a 93-acre mesotrophic lake in Waukesha County, Wisconsin with a maximum depth of 43 feet. Water quality is graded B based on 1 sampling years through 2026. The lake supports 6 documented fish species including Panfish, Largemouth Bass, and Smallmouth Bass. Public access is available. Compared to the 34 other monitored lakes in Waukesha County, Lower Nashotah Lake ranks #22 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-07-13. 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)
Moderate clarity, visible to about 9 ft. Phosphorus level: 11.3 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | Not graded |
| Phosphorus | 11.3 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lower Nashotah Lake
Compare lakeside cabins, hotels, and vacation rentals near Lower Nashotah 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 Lower Nashotah Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Lower Nashotah Lake typically sits around 76°F at the surface in August. Summer average is about 75°F. Usually warmest in Jul (about 77°F) and coldest in May (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 25 field readings (2024–2026) via the EPA Water Quality Portal. See the full Lower Nashotah Lake water temperature breakdown →
Wisconsin DNR lists Panfish as common on Lower Nashotah Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Lower Nashotah Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is stable. 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 1987. 2 stations on file (most recent sample 2026).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 43 ft |
| Surface Area | 93 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Lower Nashotah 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.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
Water Quality Trend: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.057 m/yr | 7 |
| Phosphorus | → Stable | -0.04 µg/L/yr | 7 |
County Ranking
Ranked #22 of 35 lakes in Waukesha County
Nearby Lakes in Waukesha County
Frequently asked questions about Lower Nashotah Lake
Where is Lower Nashotah Lake?
- Lower Nashotah 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 Lower Nashotah Lake?
- Lower Nashotah Lake in Waukesha County, Wisconsin has a water quality grade of B (Good). Water clarity: 9 ft visibility. Phosphorus: 11.3 µg/L. Maximum depth: 43 ft. Surface area: 93 acres.
Is Lower Nashotah Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Lower Nashotah Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Lower Nashotah Lake?
- Lower Nashotah Lake typically sits around 76°F at the surface in August, from 25 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Lower Nashotah Lake?
- Lower Nashotah Lake has a maximum depth of 43 feet. The lake covers 93 acres.
What fish are in Lower Nashotah Lake?
- Fish species found in Lower Nashotah Lake include Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Trout, Walleye. Lower Nashotah Lake is located in Waukesha County, Wisconsin.
What did the DNR fisheries survey find at Lower Nashotah Lake?
- Wisconsin DNR lists Panfish as common on Lower Nashotah Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Lower Nashotah Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
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Where this data comes from
78 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_WQX78 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Fish and recreation data from Wisconsin DNR Lakes