Island Lake
Iron County, WisconsinLimited DataEutrophic
On the LakeGrade rubric Island Lake fails the cutoffs — a TSI of 60 and persistent algal pressure put it in the bottom tier.
Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake bottoms out at 17 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 344 acres, Island Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Within the 33 graded lakes of Iron County, Island Lake sits at rank 33, near the bottom of the county list.
An invasive species record — Banded Mystery Snail — has been logged at Island Lake; Wisconsin DNR maintains the official infested-waters list. The fishery includes walleye among the lake's 5 documented species — a notable draw for Wisconsin anglers. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-09-24. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 3.2 ft of visibility. Trophic State Index: 60.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.2 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 60 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 17 ft |
| Surface Area | 344 acres |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Island Lake (14-day solunar calendar)
→ Is it safe to eat fish from Island Lake? (mercury & PFAS guide)
→ Island Lake fishing regulations (limits, seasons, special rules)
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: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.142 m/yr | 6 |
Location
County Ranking
Ranked #33 of 33 lakes in Iron County
Cleaner Lakes Within 30 Miles
Island Lake holds Grade F. 5 nearby lakes hold higher grades.
- BLittle Pine LakeIron County · mi · Two grade letters higher (F → B)
- BPine LakeIron County · mi · Two grade letters higher (F → B)
- BLake of the FallsIron County · mi · Two grade letters higher (F → B)
- CFirst Black LakeIron County · mi · Two grade letters higher (F → C)
- CGile Flowage LakeIron County · mi · Two grade letters higher (F → C)
Nearby Lakes in Iron County
More Wisconsin Lake Rankings
State Parks Near Island Lake
Other Grade F Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2019. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Island Lake covering fish populations, stocking, water quality, and management. 1 report on file.
- 2024Island Lake shocking and netting survey, 2024Netting Survey · WI DNR · 2024 (PDF)
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 WI10008930 · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-09-24
Monitoring stations: 1