Big Bass Lake
Big Bass Lake in Marathon County, Wisconsin has a water quality grade of B (Good). Water clarity: 6 ft visibility. Phosphorus: 19 µg/L. Maximum depth: 13 ft. Surface area: 177 acres.
- Clarity
- 6 ft
- Typical in August
- 75°F
- Max depth
- 13 ft
- Area
- 177 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Marathon County
Big Bass Lake is a 177-acre mesotrophic lake in Marathon County, Wisconsin with a maximum depth of 13 feet. Water quality is graded B based on 1 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 3 documented fish species including Panfish, Largemouth Bass, and Northern Pike. Public access is available with 1 public boat landing. Compared to the 3 other monitored lakes in Marathon County, Big Bass Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-09-27. Grade methodology: LakeGrade methodology.
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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)
Murky, only visible to about 6 ft. Phosphorus level: 19 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6 ft | Not graded |
| Phosphorus | 19 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Big Bass Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Bass 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.
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Water Temperature
Big Bass Lake typically sits around 75°F at the surface in August. Summer average is about 78°F. Usually warmest in Jun (about 80°F) and coldest in Oct (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 99 field readings (2024–2025) via the EPA Water Quality Portal. See the full Big Bass Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 13 ft |
| Surface Area | 177 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Big Bass LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Big Bass 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. Monitored by volunteers since 1994. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.299 m/yr | 6 |
| Phosphorus | ↑ Improving | -2.06 µg/L/yr | 6 |
EPA Impairment Status
Big Bass 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 WI10008654 · Official waterbody report
County Ranking
Ranked #1 of 4 lakes in Marathon County
Nearby Lakes in Marathon County
Frequently asked questions about Big Bass Lake
What is the water quality grade for Big Bass Lake?
- Big Bass Lake in Marathon County, Wisconsin has a water quality grade of B (Good). Water clarity: 6 ft visibility. Phosphorus: 19 µg/L. Maximum depth: 13 ft. Surface area: 177 acres.
Is Big Bass Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Big Bass Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Big Bass Lake?
- Big Bass Lake typically sits around 75°F at the surface in August, from 99 EPA Water Quality Portal field readings (2024–2025). That is a typical value for the month, not a live reading.
How deep is Big Bass Lake?
- Big Bass Lake has a maximum depth of 13 feet. The lake covers 177 acres.
What fish are in Big Bass Lake?
- Fish species found in Big Bass Lake include Panfish, Largemouth Bass, Northern Pike. Big Bass Lake is located in Marathon County, Wisconsin.
Are there boat ramps on Big Bass Lake?
- Big Bass Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Bass Lake. Public access is listed as yes.
Explore Big Bass Lake across LakeGrade
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Moderate nutrients, good water quality
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Where this data comes from
97 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX97 samples · 2020–2025
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