Lake Butte des Morts
Lake Butte des Morts in Winnebago County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 2.3 ft visibility. Maximum depth: 9 ft. Surface area: 8581 acres.
Wisconsin DNR rates Panfish, Northern Pike, Sturgeon, and Catfish as abundant on Lake Butte des Morts. DNR survey details →
- Clarity
- 2.3 ft
- Typical in August
- 74°F
- Max depth
- 9 ft
- Area
- 8,581 acres
- Trend
- → Stable
- Public access
- Yes
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Why Lake Butte des Morts has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Lake Butte des Morts, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by WI DNR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lake Butte des Morts is a 8,581-acre lake in Winnebago County, Wisconsin with a maximum depth of 9 feet. The lake supports 8 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-05-27. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lake Butte des Morts
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 2.3 ft of visibility. Trophic State Index: 65.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.3 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 65 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Lake Butte des Morts
Compare lakeside cabins, hotels, and vacation rentals near Lake Butte des Morts in Winnebago 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 Lake Butte des Morts
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Planning a trip? Cabins and lodging at Lake Butte des Morts → · more Wisconsin lake trips
Water Temperature
Lake Butte des Morts typically sits around 74°F at the surface in August. Summer average is about 75°F. Usually warmest in Jul (about 76°F) and coldest in Oct (about 52°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 44 field readings (2024–2026) via the EPA Water Quality Portal. See the full Lake Butte des Morts water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Lake Butte des Morts — clouds, ice, or an off-season gap in coverage. The most recent reading was high (912,011 cells/mL) on July 18, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR rates Panfish, Northern Pike, Sturgeon, and Catfish as abundant on Lake Butte des Morts.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Lake Butte des Morts — official chemistry is on file, not a letter, and the water-quality trend over 5 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. 31 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Lake Butte des Morts covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2023Sunset Bay (Lake Butte des Morts) spring shocking survey, 2023Spring Shocking Survey · WI DNR · 2023 (PDF)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 9 ft |
| Surface Area | 8,581 acres |
| Public Access | Yes |
Recreation & Access
- Lake Butte des MortsPublic
- Rainbow ParkPublic
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 Lake Butte des Morts
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: → Stable
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.024 m/yr | 5 |
EPA Impairment Status
Lake Butte des Morts is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit WI10000955 · Official waterbody report
Regulated Pollution Sources Nearby
3 EPA-permitted facilities operate within about 5 miles of Lake Butte des Morts under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 2 facilities have a reported Clean Water Act violation in the past three years.
- Oshkosh Wastewater Treatment PlantOshkosh · 3.5 mi away · NPDES WI0025038MajorRecent violation
- Butte Des Morts Consolidated Sd 1Winneconne · 3.8 mi away · NPDES WI0032492Recent violation
- Michels Materials Fl&B Sheppard QuarryOshkosh · 1.3 mi away · NPDES WI0058564
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.
Graded lakes near Lake Butte des Morts
Lake Butte des Morts has no grade, but these lakes within a short drive do.
Nearby Lakes in Winnebago County
Frequently asked questions about Lake Butte des Morts
Where is Lake Butte des Morts?
- Lake Butte des Morts is a lake in Winnebago County, Wisconsin. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Lake Butte des Morts?
- Lake Butte des Morts in Winnebago County, Wisconsin is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 2.3 ft visibility. Maximum depth: 9 ft. Surface area: 8581 acres.
Is Lake Butte des Morts safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lake Butte des Morts is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Lake Butte des Morts?
- Lake Butte des Morts typically sits around 74°F at the surface in August, from 44 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Lake Butte des Morts?
- Lake Butte des Morts has a maximum depth of 9 feet. The lake covers 8581 acres.
What fish are in Lake Butte des Morts?
- Fish species found in Lake Butte des Morts include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye, Sturgeon, Catfish. Lake Butte des Morts is located in Winnebago County, Wisconsin.
What did the DNR fisheries survey find at Lake Butte des Morts?
- Wisconsin DNR rates Panfish, Northern Pike, Sturgeon, and Catfish as abundant on Lake Butte des Morts. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality does not assign an A–F grade on Lake Butte des Morts — official chemistry is on file, not a letter, and the water-quality trend over 5 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Does Lake Butte des Morts have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Lake Butte des Morts (clouds, ice, or an off-season gap). The most recent reading was high (912,011 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Are there boat ramps on Lake Butte des Morts?
- Lake Butte des Morts has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Lake Butte des Morts, Rainbow Park. Public access is listed as yes.
Explore Lake Butte des Morts across LakeQuality
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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
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
Impairment status from EPA ATTAINS 303(d) database
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