Long Lake
Long Lake in Washburn County, Wisconsin has a water quality grade of B (Good). Water clarity: 9.5 ft visibility. Phosphorus: 17.3 µg/L. Surface area: 3290 acres.
- Clarity
- 9.5 ft
- Area
- 3,290 acres
- Type
- Mesotrophic
- Public access
- Yes
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Long Lake is a 3,290-acre mesotrophic lake in Washburn County, Wisconsin. Water quality is graded B based on 1 sampling years through 2026. Limited fish-species data available. Public access is available with 3 public boat landings. Compared to the 26 other monitored lakes in Washburn County, Long Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2026-06-30. Grade methodology: LakeQuality 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)
Moderate clarity, visible to about 9.5 ft. Phosphorus level: 17.3 µg/L. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.5 ft | Not graded |
| Phosphorus | 17.3 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Long Lake
Compare lakeside cabins, hotels, and vacation rentals near Long Lake in Washburn 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 Long Lake
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Planning a trip? Cabins and lodging at Long Lake → · more Wisconsin lake trips
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 3,290 acres |
| Public Access | Yes |
No bathymetric survey has been published for Long Lake, so its depth is not documented here.
Recreation & Access
- Long LakePublic
- Hanks - Long LakePublic
- Big Devils LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Long Lake
Reservoir Info (USACE NID)
Long Lake is a man-made reservoir impounded by the Long Lake (completed 1913), built primarily for recreation on the BRILL; gravity-type dam, 15 ft tall and 575 ft long.
- Surface area
- 3,290 ac
- Normal storage
- 15,000 ac-ft
- Max storage
- 35,000 ac-ft
- Drainage area
- 82 sq mi
- Hazard class
- High
- Owner
- Washburn County
Source: USACE National Inventory of Dams, NID ID WI00325 · Operator website
EPA Impairment Status
Long Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5R).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10004589 · Official waterbody report
County Ranking
Ranked #4 of 27 lakes in Washburn County
Nearby Lakes in Washburn County
Frequently asked questions about Long Lake
Where is Long Lake?
- Long Lake is a lake in Washburn County, Wisconsin. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Long Lake?
- Long Lake in Washburn County, Wisconsin has a water quality grade of B (Good). Water clarity: 9.5 ft visibility. Phosphorus: 17.3 µg/L. Surface area: 3290 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.
Are there boat ramps on Long Lake?
- Long Lake has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Long Lake, Hanks - Long Lake, Big Devils Lake. Public access is listed as yes.
Explore Long Lake across LakeQuality
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Moderate nutrients, good water quality
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Where this data comes from
193 measurements from 6 monitoring stations, 2020–2026. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX193 samples · 2020–2026
Analytical methods
- Phosphorus by Colorimetry
- Total Phosphorus After Block Digestion
- Turbidity in Water
Monitoring station identifiers (6)
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
Named boat-access points from the USGS National Boat Ramps inventory