Butternut Lake
Forest County, Wisconsin1,246 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Butternut Lake. Here is what has been measured.
- Oligotrophic
- 2 aquatic invasives
- 42 ft max depth
- Public access
Butternut Lake in Forest County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 19.5 ft visibility. Phosphorus: 12.1 µg/L. Maximum depth: 42 ft. Surface area: 1246 acres.
Wisconsin DNR rates Smallmouth Bass and Walleye as abundant on Butternut Lake. DNR survey details →
Butternut Lake is a 1,246-acre cold, clear oligotrophic lake in Forest County, Wisconsin with a maximum depth of 42 feet. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Panfish, Smallmouth Bass, and Northern Pike. Public access is available with 2 public boat landings. Compared to the 22 other monitored lakes in Forest County, Butternut Lake ranks #10 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-05-07. Methodology: how these readings are compared.
What Butternut Lake is good for
From access and monitoring records, not editorial picks.
- Clear water19.5 ft of visibility
- Boat launch2 documented ramps
- Fishing4 species recorded
- Deep water42 ft surveyed max depth
- Big water1,246 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 Butternut 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 Butternut Lake
These are the measurements Wisconsin DNR publishes for Butternut Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 19.5 ft down. Phosphorus 12.1 µg/L. TSI 37.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 19.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 12.1µg/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. | 37 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Butternut Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Butternut Lake typically sits around 73°F at the surface in August. Summer average is about 73°F. Usually warmest in Jul (about 77°F) and coldest in Jun (about 68°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (68°F) to its warmest (77°F).
Typical surface water temperature by month, from 11 field readings (2024–2025) via the EPA Water Quality Portal. See the full Butternut Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Butternut Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was moderate (33,113 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 rates Smallmouth Bass and Walleye as abundant on Butternut Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Butternut 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. Monitored by volunteers since 1987. 6 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
Max depth
42 ft
Surface area
1,246 acres
Public access
Yes
Listed by Wisconsin DNR
Lake Size & Watershed
Watershed (drainage) area
13 sq mi
HydroLAKES / HydroSHEDS
Shoreline
7.6 mi
HydroLAKES / HydroSHEDS
Elevation
1,683 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Butternut Lake - NorthPublic
- Butternut Lake - SouthPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Butternut Lake
Compare lakeside cabins, hotels, and vacation rentals near Butternut Lake in Forest 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 Butternut Lake
Prices for Oct 9–11, 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 Butternut Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fish Species
Click a species to see every lake where it is documented.
Fishing Butternut 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-0.34 µg/L/yr6 years
Nearby Lakes in Forest County
Frequently asked questions about Butternut Lake
Where is Butternut Lake?
- Butternut Lake is a lake in Forest County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Butternut Lake?
- Butternut Lake in Forest County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 19.5 ft visibility. Phosphorus: 12.1 µg/L. Maximum depth: 42 ft. Surface area: 1246 acres.
Is Butternut 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 Butternut Lake?
- Butternut Lake typically sits around 73°F at the surface in August, from 11 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Butternut Lake?
- Butternut Lake has a maximum depth of 42 feet. The lake covers 1246 acres.
What fish are in Butternut Lake?
- Fish species found in Butternut Lake include Panfish, Smallmouth Bass, Northern Pike, Walleye. Butternut Lake is located in Forest County, Wisconsin.
What did the DNR fisheries survey find at Butternut Lake?
- Wisconsin DNR rates Smallmouth Bass and Walleye as abundant on Butternut Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Butternut 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 Butternut Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Butternut Lake (clouds, ice, or an off-season gap). The most recent reading was moderate (33,113 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Butternut Lake?
- Butternut Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Butternut Lake - North, Butternut Lake - South. Public access is listed as yes.
Can I fish at Butternut Lake?
- Butternut Lake has 2 documented boat landings 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 Butternut Lake across LakeQuality
Fish species and the cleanest lakes across Wisconsin
Fish species and best lakes in Forest County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Northwoods Wisconsin area
Where to stay at Wisconsin's top lakes, each with its readings
Lakes in the Wolf River Watershed, ranked by water quality
Wisconsin's cleanest lakes, ranked on agency measurements
More lakes in Wisconsin
Other Lakes in Wisconsin
Oligotrophic Lakes in Wisconsin
Compare Butternut Lake With Nearby Lakes
Where this data comes from
37 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_WQX37 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
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