Unknown Lake
Grant County, WisconsinView mapDirections
Wisconsin DNR publishes the water-quality measurements for Unknown Lake. Here is what has been measured.
- Eutrophic
- Limited data
Unknown Lake in Grant County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 2.4 ft visibility. Phosphorus: 135.5 µg/L.
Unknown Lake is a productive, nutrient-rich eutrophic lake in Grant County, Wisconsin. Compared to the 2 other monitored lakes in Grant County, Unknown Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2022-10-27. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
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 Unknown 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 Unknown Lake
These are the measurements Wisconsin DNR publishes for Unknown Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2.4 ft of visibility. Phosphorus 135.5 µg/L. TSI 70.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.4ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 136µg/L | Poor 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. | 70 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
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Stays near Unknown Lake
Compare lakeside cabins, hotels, and vacation rentals near Unknown Lake in Grant 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Unknown Lake are listed below.
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Fishing Unknown Lake
Nearby Lakes in Grant County
Frequently asked questions about Unknown Lake
Where is Unknown Lake?
- Unknown Lake is a lake in Grant County, Wisconsin. Its water-quality measurements are published by Wisconsin DNR and shown on this page as reported.
What is the water quality of Unknown Lake?
- Unknown Lake in Grant County, Wisconsin has water-quality measurements published by Wisconsin DNR, shown here as reported. Water clarity: 2.4 ft visibility. Phosphorus: 135.5 µg/L.
Is Unknown Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Unknown Lake across LakeQuality
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Where this data comes from
24 measurements from 2 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Wisconsin Department of Natural Resources
WIDNR_WQX24 samples · 2022
Analytical methods
- Phosphorus by Colorimetry
Monitoring station identifiers (2)
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.