Long Lake
Washburn County, Wisconsin3,290 acresView mapDirections
Wisconsin DNR publishes the water-quality measurements for Long Lake. Here is what has been measured.
- Mesotrophic
- Public access
Long Lake in Washburn County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 9.5 ft visibility. Phosphorus: 17.3 µg/L. Surface area: 3290 acres.
Long Lake is a 3,290-acre mesotrophic lake in Washburn County, Wisconsin. Limited fish-species data available. Public access is available. 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. Methodology: how these readings are compared.
Long Lake covers about 3,300 acres in Washburn County. For a place on the water, look through cabin and lake-house rentals near Long Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Long Lake is good for
From access and monitoring records, not editorial picks.
- Big water3,290 acres
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Long Lake is safe to swim in today is a call for the Wisconsin Department of Natural Resources and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Long Lake
These are the measurements Wisconsin DNR publishes for Long Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Moderate clarity, visible to about 9.5 ft. Phosphorus 17.3 µg/L. TSI 45.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 9.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 17.3µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 45 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Long Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
3,290 acres
Public access
Yes
Listed by Wisconsin DNR
No bathymetric survey has been published for Long Lake, so its depth is not documented here.
Stays via Stay22
Stays 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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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
Nearby Lakes in Washburn County
Frequently asked questions about Long Lake
Where is Long Lake?
- Long Lake is a lake in Washburn County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Long Lake?
- Long Lake in Washburn County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 9.5 ft visibility. Phosphorus: 17.3 µg/L. Surface area: 3290 acres.
Is Long Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Can I fish at Long Lake?
- Public access to Long Lake is listed as yes on the lake record. Seasons, size and bag limits, and whether you need a license are set by Wisconsin's fish and wildlife agency, so check its current regulations before you go.
Explore Long Lake across LakeQuality
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.