Fourmile Lake
Oneida County, Wisconsin210 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Fourmile Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- Rusty Crayfish
- 29 ft max depth
- Public access
- Limited data
Fourmile Lake in Oneida County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. 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 →
Fourmile Lake is a 210-acre productive, nutrient-rich eutrophic lake in Oneida County, Wisconsin with a maximum depth of 29 feet. 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. 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. Methodology: how these readings are compared.
What Fourmile Lake is good for
From access and monitoring records, not editorial picks.
- Fishing6 species recorded
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Fourmile Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Whether Fourmile Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Fourmile Lake
These are the measurements Wisconsin DNR publishes for Fourmile Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 3 ft of visibility. Phosphorus 28.9 µg/L. TSI 57.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 28.9µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 57 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Fourmile Lake
Answers come straight from the public measurements and survey records on this page.
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.
Column height runs from this lake’s coldest month (69°F) to its warmest (73°F).
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 water quality. LakeQuality shows Fourmile Lake’s water-quality measurements separately, 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
Max depth
29 ft
Surface area
210 acres
Public access
Yes
Listed by Wisconsin DNR
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Stays near Fourmile Lake
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Fish Species
Click a species to see every 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 (2020–2026).
Water clarity
Improving7 years
Phosphorus
Improving-1.85 µg/L/yr4 years
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
Designated uses not supporting: Fish consumption.
Source: EPA ATTAINS assessment unit WI10007283 · Official waterbody report
Nearby Lakes in Oneida County
Frequently asked questions about Fourmile Lake
Where is Fourmile Lake?
- Fourmile Lake is a lake in Oneida County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Fourmile Lake?
- Fourmile Lake in Oneida County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. 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?
- Nutrient and algae readings are not a swimming clearance. Fourmile Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
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 water quality. LakeQuality shows Fourmile Lake’s water-quality measurements separately, 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.
Can I fish at Fourmile Lake?
- Public access to Fourmile Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Fish and recreation data from Wisconsin DNR Lakes