Upper Nemahbin Lake
Waukesha County, Wisconsin277 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Upper Nemahbin Lake. Here is what has been measured.
- Mesotrophic
- 2 aquatic invasives
- 60 ft max depth
- Public access
Upper Nemahbin Lake in Waukesha County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 12 ft visibility. Phosphorus: 13.7 µg/L. Maximum depth: 60 ft. Surface area: 277 acres.
Wisconsin DNR lists Panfish as common on Upper Nemahbin Lake. DNR survey details →
Upper Nemahbin Lake is a 277-acre mesotrophic lake in Waukesha County, Wisconsin with a maximum depth of 60 feet. Overall water quality is improving over recent sampling years. The lake supports 5 documented fish species including Panfish, Largemouth Bass, and Smallmouth Bass. Public access is available with 1 public boat landing. Compared to the 34 other monitored lakes in Waukesha County, Upper Nemahbin Lake ranks #28 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-26. Methodology: how these readings are compared.
Upper Nemahbin Lake covers about 280 acres in Waukesha County. It has one public boat landing. For a place on the water, look through cabin and lake-house rentals near Upper Nemahbin Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Upper Nemahbin Lake is good for
From access and monitoring records, not editorial picks.
- Clear water12 ft of visibility
- Boat launch1 documented ramp
- Fishing5 species recorded
- Deep water60 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 Upper Nemahbin 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 Upper Nemahbin Lake
These are the measurements Wisconsin DNR publishes for Upper Nemahbin 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 12 ft. Phosphorus 13.7 µg/L. TSI 42.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 12ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 13.7µg/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. | 42 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Upper Nemahbin Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Upper Nemahbin Lake typically sits around 74°F at the surface in August. Summer average is about 77°F. Usually warmest in Jul (about 79°F) and coldest in Aug (about 74°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (74°F) to its warmest (79°F).
Typical surface water temperature by month, from 8 field readings (2024–2025) via the EPA Water Quality Portal. See the full Upper Nemahbin Lake water temperature breakdown →
Wisconsin DNR lists Panfish as common on Upper Nemahbin Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Upper Nemahbin Lake’s water-quality measurements separately, and the water-quality trend over 7 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. 4 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
60 ft
Surface area
277 acres
Public access
Yes
Listed by Wisconsin DNR
Recreation & Access
- Nemahbin LakesPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Upper Nemahbin Lake
Compare lakeside cabins, hotels, and vacation rentals near Upper Nemahbin 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 Upper Nemahbin Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Upper Nemahbin Lake
- → Upper Nemahbin Lake fishing: DNR survey catch rates, species & stocking
- → Upper Nemahbin Lake fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Upper Nemahbin Lake fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Upper Nemahbin Lake? (mercury & PFAS guide)
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 7 years of monitoring (2020–2026).
Water clarity
Improving7 years
Phosphorus
Improving-0.54 µg/L/yr7 years
Nearby Lakes in Waukesha County
Frequently asked questions about Upper Nemahbin Lake
Where is Upper Nemahbin Lake?
- Upper Nemahbin 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 Upper Nemahbin Lake?
- Upper Nemahbin Lake in Waukesha County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 12 ft visibility. Phosphorus: 13.7 µg/L. Maximum depth: 60 ft. Surface area: 277 acres.
Is Upper Nemahbin 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 Upper Nemahbin Lake?
- Upper Nemahbin Lake typically sits around 74°F at the surface in August, from 8 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Upper Nemahbin Lake?
- Upper Nemahbin Lake has a maximum depth of 60 feet. The lake covers 277 acres.
What fish are in Upper Nemahbin Lake?
- Fish species found in Upper Nemahbin Lake include Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Upper Nemahbin Lake is located in Waukesha County, Wisconsin.
What did the DNR fisheries survey find at Upper Nemahbin Lake?
- Wisconsin DNR lists Panfish as common on Upper Nemahbin Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Upper Nemahbin Lake’s water-quality measurements separately, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Upper Nemahbin Lake?
- Upper Nemahbin Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Nemahbin Lakes. Public access is listed as yes.
Can I fish at Upper Nemahbin Lake?
- Upper Nemahbin 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 Upper Nemahbin 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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State Parks Near Upper Nemahbin Lake
Other Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
Where this data comes from
48 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_WQX48 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
Fish and recreation data from Wisconsin DNR Lakes
Named boat-access points from the USGS National Boat Ramps inventory