Long Lake
Long Lake in Lincoln County, Wisconsin has a water quality grade of B (Good). Water clarity: 14.5 ft visibility. Phosphorus: 12.4 µg/L. Maximum depth: 64 ft. Surface area: 119 acres.
- Clarity
- 14.5 ft
- Max depth
- 64 ft
- Area
- 119 acres
- Type
- Oligotrophic
- Trend
- ↑ Improving
- Public access
- Yes
Next lake in Lincoln County
Long Lake is a 119-acre cold, clear oligotrophic lake in Lincoln County, Wisconsin with a maximum depth of 64 feet. Water quality is graded B based on 1 sampling years through 2026. Overall water quality is improving over recent sampling years. The lake supports 4 documented fish species including Musky, Panfish, and Largemouth Bass. Public access is available with 2 public boat landings. Compared to the 12 other monitored lakes in Lincoln County, Long Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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 14.5 ft. Phosphorus level: 12.4 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.5 ft | Not graded |
| Phosphorus | 12.4 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long 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 | 64 ft |
| Surface Area | 119 acres |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Seven Island LakePublic
- Dudley LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long 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 1994. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
Water Quality Trend: ↑ Improving
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.334 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.83 µg/L/yr | 7 |
EPA Impairment Status
Long 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
County Ranking
Ranked #4 of 13 lakes in Lincoln County
Nearby Lakes in Lincoln County
Frequently asked questions about Long Lake
What is the water quality grade for Long Lake?
- Long Lake in Lincoln County, Wisconsin has a water quality grade of B (Good). Water clarity: 14.5 ft visibility. Phosphorus: 12.4 µg/L. Maximum depth: 64 ft. Surface area: 119 acres.
Is Long Lake safe to swim in?
- Good for swimming, clear water with low algae levels. Long Lake has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Long Lake?
- Long Lake has a maximum depth of 64 feet. The lake covers 119 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include Musky, Panfish, Largemouth Bass, Northern Pike. Long Lake is located in Lincoln County, Wisconsin.
Are there boat ramps on Long Lake?
- Long Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Seven Island Lake, Dudley Lake. Public access is listed as yes.
Explore Long Lake across LakeGrade
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Low nutrients, clear water, excellent for swimming
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Where this data comes from
38 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_WQX38 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