Island Lake
Island Lake in Oneida County, Wisconsin has a water quality grade of B (Good). Water clarity: 7 ft visibility. Phosphorus: 21.5 µg/L. Maximum depth: 26 ft. Surface area: 305 acres.
Wisconsin DNR rates Walleye as abundant on Island Lake. DNR survey details →
- Clarity
- 7 ft
- Typical in July
- 63°F
- Max depth
- 26 ft
- Area
- 305 acres
- Type
- Mesotrophic
- Trend
- → Stable
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Island Lake is a 305-acre mesotrophic lake in Oneida County, Wisconsin with a maximum depth of 26 feet. Water quality is graded B based on 1 sampling years through 2026. The lake supports 6 documented fish species including Musky, Panfish, and Largemouth Bass. Compared to the 66 other monitored lakes in Oneida County, Island Lake ranks #11 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-23. 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.
Good for swimming, clear water with low algae levels
Water Quality Grade: B (Good)
Moderate clarity, visible to about 7 ft. Phosphorus level: 21.5 µg/L. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7 ft | Not graded |
| Phosphorus | 21.5 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Island 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 Island Lake
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Planning a whole trip? See where to stay at Wisconsin’s top lakes →
Water Temperature
Island Lake typically sits around 63°F at the surface in July. Summer average is about 63°F. Usually warmest in Jul (about 63°F) and coldest in Feb (about 37°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 11 field readings (2025–2026) via the EPA Water Quality Portal. See the full Island Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Island Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (293,765 cells/mL) on May 2, 2026.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Wisconsin DNR rates Walleye as abundant on Island Lake.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Island Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is stable. 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 1979. 1 station on file (most recent sample 2026).
Fish Species (DNR-rated)
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 26 ft |
| Surface Area | 305 acres |
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Island 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: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.045 m/yr | 7 |
| Phosphorus | → Stable | 0 µg/L/yr | 2 |
EPA Impairment Status
Island 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 WI10007314 · Official waterbody report
County Ranking
Ranked #11 of 67 lakes in Oneida County
Nearby Lakes in Oneida County
Frequently asked questions about Island Lake
Where is Island Lake?
- Island Lake is a lake in Oneida County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Island Lake?
- Island Lake in Oneida County, Wisconsin has a water quality grade of B (Good). Water clarity: 7 ft visibility. Phosphorus: 21.5 µg/L. Maximum depth: 26 ft. Surface area: 305 acres.
Is Island Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Island Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
What is the water temperature of Island Lake?
- Island Lake typically sits around 63°F at the surface in July, from 11 EPA Water Quality Portal field readings (2025–2026). That is a typical value for the month, not a live reading.
How deep is Island Lake?
- Island Lake has a maximum depth of 26 feet. The lake covers 305 acres.
What fish are in Island Lake?
- Fish species found in Island Lake include Musky, Panfish, Largemouth Bass, Smallmouth Bass, Northern Pike, Walleye. Island Lake is located in Oneida County, Wisconsin.
What did the DNR fisheries survey find at Island Lake?
- Wisconsin DNR rates Walleye as abundant on Island Lake. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Island Lake B from EPA Water Quality Portal chemistry, and the water-quality trend over 7 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
Does Island Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Island Lake (clouds, ice, or an off-season gap). The most recent reading was high (293,765 cells/mL). Blue-green algae can appear and clear within days, so check Wisconsin's current advisory before swimming.
Explore Island Lake across LakeQuality
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Where this data comes from
43 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_WQX43 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