Fourmile Lake
Fourmile Lake in Oneida County, Wisconsin has a water quality grade of C (Fair). Water clarity: 3 ft visibility. Phosphorus: 28.9 µg/L. Maximum depth: 29 ft. Surface area: 210 acres.
Wisconsin DNR lists Musky as common on Fourmile Lake. DNR survey details →
- Clarity
- 3 ft
- Typical in August
- 73°F
- Max depth
- 29 ft
- Area
- 210 acres
- Type
- Eutrophic
- Trend
- ↑ Improving
- Public access
- Yes
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Fourmile Lake is a 210-acre productive, nutrient-rich eutrophic lake in Oneida County, Wisconsin with a maximum depth of 29 feet. Water quality is graded C based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 1 public boat landing. Compared to the 66 other monitored lakes in Oneida County, Fourmile Lake ranks #61 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-17. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyLimited data
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Very murky, less than 3 ft of visibility. Phosphorus level: 28.9 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3 ft | Not graded |
| Phosphorus | 28.9 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Fourmile Lake
Compare lakeside cabins, hotels, and vacation rentals near Fourmile Lake in Oneida 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 Fourmile Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Fourmile Lake typically sits around 73°F at the surface in August. Summer average is about 71°F. Usually warmest in Aug (about 73°F) and coldest in Jun (about 69°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 10 field readings (2024–2026) via the EPA Water Quality Portal. See the full Fourmile Lake water temperature breakdown →
Wisconsin DNR lists Musky as common on Fourmile Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Fourmile Lake C from EPA Water Quality Portal chemistry, and the water-quality trend over 7 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 1993. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 29 ft |
| Surface Area | 210 acres |
| Public Access | Yes |
Recreation & Access
- Big Fork LakePublic
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 Fourmile 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 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.368 m/yr | 7 |
| Phosphorus | ↑ Improving | -1.85 µg/L/yr | 4 |
EPA Impairment Status
Fourmile 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 WI10007283 · Official waterbody report
County Ranking
Ranked #61 of 67 lakes in Oneida County
Nearby Lakes With Higher Grades
Fourmile Lake holds Grade C. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Oneida County
Frequently asked questions about Fourmile Lake
Where is Fourmile Lake?
- Fourmile Lake is a lake in Oneida County, Wisconsin. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Fourmile Lake?
- Fourmile Lake in Oneida County, Wisconsin has a water quality grade of C (Fair). Water clarity: 3 ft visibility. Phosphorus: 28.9 µg/L. Maximum depth: 29 ft. Surface area: 210 acres.
Is Fourmile Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Fourmile Lake has a water quality grade of C (Fair). Always check local health department advisories before swimming.
What is the water temperature of Fourmile Lake?
- Fourmile Lake typically sits around 73°F at the surface in August, from 10 EPA Water Quality Portal field readings (2024–2026). That is a typical value for the month, not a live reading.
How deep is Fourmile Lake?
- Fourmile Lake has a maximum depth of 29 feet. The lake covers 210 acres.
What fish are in Fourmile Lake?
- Fish species found in Fourmile Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Fourmile Lake is located in Oneida County, Wisconsin.
What did the DNR fisheries survey find at Fourmile Lake?
- Wisconsin DNR lists Musky as common on Fourmile Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Fourmile Lake C from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Fourmile Lake?
- Fourmile Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Big Fork Lake. Public access is listed as yes.
Explore Fourmile Lake 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
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