Seven Island Lake
Seven Island Lake in Lincoln County, Wisconsin has a water quality grade of B (Good). Water clarity: 14 ft visibility. Phosphorus: 9.9 µg/L. Maximum depth: 31 ft. Surface area: 132 acres.
- Clarity
- 14 ft
- Max depth
- 31 ft
- Area
- 132 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Lincoln County
Seven Island Lake is a 132-acre cold, clear oligotrophic lake in Lincoln County, Wisconsin with a maximum depth of 31 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 5 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 6 public boat landings. Compared to the 12 other monitored lakes in Lincoln County, Seven Island Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-31. Grade methodology: LakeGrade 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)
Good clarity, visible to about 14 ft. Phosphorus level: 9.9 µg/L. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14 ft | Not graded |
| Phosphorus | 9.9 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Seven Island Lake
Compare lakeside cabins, hotels, and vacation rentals near Seven Island Lake in Lincoln 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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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 31 ft |
| Surface Area | 132 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Long LakePublic
- Lake TwoPublic
- Two Island LakePublic
- Bennett LakePublic
- Fox LakePublic
- Perch Lake - 1Public
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Seven 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.
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)
DNR Reports & Resources
Wisconsin DNR Fisheries scientists publish multi-year survey reports for Seven Island Lake covering fish populations, stocking, water quality, and management. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 2024Seven Island Lake spring summary report, 2024Fisheries Survey · WI DNR · 2024 (PDF)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.434 m/yr | 6 |
| Phosphorus | ↑ Improving | -0.67 µg/L/yr | 7 |
EPA Impairment Status
Seven 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 WI10026794 · Official waterbody report · Matched by proximity (1.15 km)
County Ranking
Ranked #5 of 13 lakes in Lincoln County
Nearby Lakes in Lincoln County
Frequently asked questions about Seven Island Lake
What is the water quality grade for Seven Island Lake?
- Seven Island Lake in Lincoln County, Wisconsin has a water quality grade of B (Good). Water clarity: 14 ft visibility. Phosphorus: 9.9 µg/L. Maximum depth: 31 ft. Surface area: 132 acres.
Is Seven Island Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Seven Island Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Seven Island Lake?
- Seven Island Lake has a maximum depth of 31 feet. The lake covers 132 acres.
What fish are in Seven Island Lake?
- Fish species found in Seven Island Lake include Musky, Panfish, Largemouth Bass, Northern Pike, Walleye. Seven Island Lake is located in Lincoln County, Wisconsin.
Are there boat ramps on Seven Island Lake?
- Seven Island Lake has 6 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Long Lake, Lake Two, Two Island Lake, Bennett Lake, among others. Public access is listed as yes.
Explore Seven Island Lake across LakeGrade
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Where this data comes from
51 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_WQX51 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