Butternut Lake
Butternut Lake in Forest County, Wisconsin has a water quality grade of B (Good). 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 →
- Clarity
- 19.5 ft
- Typical in August
- 73°F
- Max depth
- 42 ft
- Area
- 1,246 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Forest County
Swipe left or right on this bar to open the next or previous lake.
Butternut Lake is a 1,246-acre cold, clear oligotrophic lake in Forest County, Wisconsin with a maximum depth of 42 feet. Water quality is graded B based on 1 sampling years through 2026. 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. Grade methodology: LakeQuality methodology.
Watch Butternut Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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)
Crystal clear, you can see 19.5 ft down. Phosphorus level: 12.1 µg/L. Trophic State Index: 37.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 19.5 ft | Not graded |
| Phosphorus | 12.1 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay 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
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 →
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.
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 a water-quality grade. LakeQuality grades Butternut Lake B from EPA Water Quality Portal chemistry, 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
| Characteristic | Value |
|---|---|
| Maximum Depth | 42 ft |
| Surface Area | 1,246 acres |
| Public Access | Yes |
Lake Size & Watershed
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
Fish Species
Click a species to see every graded 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 data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.857 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.34 µg/L/yr | 6 |
County Ranking
Ranked #10 of 23 lakes in Forest County
Nearby Lakes in Forest County
Frequently asked questions about Butternut Lake
Where is Butternut Lake?
- Butternut Lake is a lake in Forest County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Butternut Lake?
- Butternut Lake in Forest County, Wisconsin has a water quality grade of B (Good). 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?
- Good for swimming, clear water with low algae levels. Butternut Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
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 a water-quality grade. LakeQuality grades Butternut Lake B from EPA Water Quality Portal chemistry, 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.
Explore Butternut Lake across LakeQuality
Fish species and top-graded 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 grade
Lakes in the Wolf River Watershed, ranked by water quality
Low nutrients, clear water, excellent for swimming
Wisconsin's cleanest and most-polluted lakes, ranked
More Wisconsin Lake Rankings
Other Grade B 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)
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
Named boat-access points from the USGS National Boat Ramps inventory