Mauthe Lake
Mauthe Lake in Fond du Lac County, Wisconsin has a water quality grade of C (Fair). Water clarity: 6 ft visibility. Phosphorus: 54 µg/L. Maximum depth: 23 ft. Surface area: 70 acres.
- Clarity
- 6 ft
- Max depth
- 23 ft
- Area
- 70 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Fond du Lac County
Mauthe Lake is a 70-acre productive, nutrient-rich eutrophic lake in Fond du Lac County, Wisconsin with a maximum depth of 23 feet. Water quality is graded C based on 1 sampling years through 2020. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 8 other monitored lakes in Fond du Lac County, Mauthe Lake ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2020-09-10. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria B
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.
Based on E. coli testing, Mauthe Lake rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 1.8% of 110 samples across 9 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Wisconsin’s current beach and health-department advisories before swimming.
Water Quality Grade: C (Fair)
Murky, only visible to about 6 ft. Phosphorus level: 54 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | Not graded |
| Phosphorus | 54 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mauthe Lake
Compare lakeside cabins, hotels, and vacation rentals near Mauthe Lake in Fond du Lac 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 Mauthe Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 23 ft |
| Surface Area | 70 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Mauthe LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Mauthe 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.
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 1 station on file (most recent sample 2020).
Fish Species (DNR-rated)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.207 m/yr | 6 |
| Phosphorus | ↑ Improving | -2.29 µg/L/yr | 7 |
EPA Impairment Status
Mauthe Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10001196 · Official waterbody report
County Ranking
Ranked #7 of 9 lakes in Fond du Lac County
Nearby Lakes With Higher Grades
Mauthe Lake holds Grade C. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Fond du Lac County
Frequently asked questions about Mauthe Lake
What is the water quality grade for Mauthe Lake?
- Mauthe Lake in Fond du Lac County, Wisconsin has a water quality grade of C (Fair). Water clarity: 6 ft visibility. Phosphorus: 54 µg/L. Maximum depth: 23 ft. Surface area: 70 acres.
Is Mauthe Lake safe to swim in?
- Based on E. coli testing, Mauthe Lake rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 1.8% of 110 samples across 9 seasons. That works out to a bacteria swim-safety grade of B — a historical summary of past testing, not a current reading. Mauthe Lake has a water quality grade of C (Fair). Bacteria levels can spike quickly after heavy rain, so always check Wisconsin's current beach and health-department advisories before you swim.
How deep is Mauthe Lake?
- Mauthe Lake has a maximum depth of 23 feet. The lake covers 70 acres.
What fish are in Mauthe Lake?
- Fish species found in Mauthe Lake include Panfish, Largemouth Bass, Northern Pike, Walleye. Mauthe Lake is located in Fond du Lac County, Wisconsin.
Are there boat ramps on Mauthe Lake?
- Mauthe Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mauthe Lake. Public access is listed as yes.
Explore Mauthe Lake across LakeGrade
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Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
6 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX6 samples · 2020
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
Impairment status from EPA ATTAINS 303(d) database
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