Big Eau Pleine Lake
Big Eau Pleine Lake in Marathon County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 1.5 ft visibility. Phosphorus: 131 µg/L.
- Clarity
- 1.5 ft
- Type
- Hypereutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Big Eau Pleine Lake →
Next lake in Marathon County
Big Eau Pleine Lake is a highly nutrient-loaded hypereutrophic lake in Marathon County, Wisconsin. Water quality is graded D based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 7 public boat landings. Compared to the 3 other monitored lakes in Marathon County, Big Eau Pleine Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-07-12. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyElevated nutrients
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.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Very murky, less than 1.5 ft of visibility. Phosphorus level: 131 µg/L. Trophic State Index: 73.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.5 ft | Not graded |
| Phosphorus | 131 µg/L | Poor |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 73 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Big Eau Pleine Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Eau Pleine Lake in Marathon 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Big Eau Pleine Lake are listed below.
Top-rated places to stay near Big Eau Pleine Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Recreation & Access
- Dauls StreetPublic
- Big Eau Pleine County Park - West UnitPublic
- Big Eau Pleine County Park - South Unit 1Public
- Big Eau Pleine County Park - South Unit 2Public
- George's LandingPublic
- Highway SPublic
Showing 6 of 7 documented landings from the USGS National Boat Ramps inventory.
Fishing Big Eau Pleine Lake
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Big Eau Pleine Lake 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).
- 2024Big Eau Pleine Reservoir comprehensive survey, 2024Comprehensive Survey · WI DNR · 2024 (PDF)
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.025 m/yr | 3 |
| Phosphorus | ↑ Improving | -19.25 µg/L/yr | 3 |
EPA Impairment Status
Big Eau Pleine Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit WI10026869 · Official waterbody report
County Ranking
Ranked #3 of 4 lakes in Marathon County
Nearby Lakes With Higher Grades
Big Eau Pleine Lake holds Grade D. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Marathon County
Frequently asked questions about Big Eau Pleine Lake
What is the water quality grade for Big Eau Pleine Lake?
- Big Eau Pleine Lake in Marathon County, Wisconsin has a water quality grade of D (Nutrient-rich). Water clarity: 1.5 ft visibility. Phosphorus: 131 µg/L.
Is Big Eau Pleine Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Big Eau Pleine Lake has a water quality grade of D (Nutrient-rich). Always check local health department advisories before swimming.
Are there boat ramps on Big Eau Pleine Lake?
- Big Eau Pleine Lake has 7 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Dauls Street, Big Eau Pleine County Park - West Unit, Big Eau Pleine County Park - South Unit 1, Big Eau Pleine County Park - South Unit 2, among others. Public access is listed as yes.
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Where this data comes from
234 measurements from 7 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_WQX234 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (7)
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
Named boat-access points from the USGS National Boat Ramps inventory