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LakeQuality
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Allequash Lake

Vilas County, WisconsinOligotrophic

Allequash Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI value of 35 puts Allequash Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Within Vilas County's 202 graded lakes, Allequash Lake ranks 131 — below the local median, though not at the bottom.

Allequash Lake has no invasive species recorded in Wisconsin state databases as of 2022, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Allequash Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2022-09-09. Grade methodology: LakeGrade methodology.

Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Crystal clear, you can see 26.8 ft down. Phosphorus level: 12.3 µg/L. Trophic State Index: 35.

MetricValueGrade
Water Clarity (Secchi Depth)26.8 ftA
Phosphorus12.3 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)35Oligotrophic

Low nutrients, clear water, excellent for swimming

Water Quality Trend: Declining

Based on 2 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-7.85 m/yr2
See year-by-year chart →

Location

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County Ranking

Ranked #131 of 202 lakes in Vilas County

Nearby Lakes in Vilas County

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Most recent sample: 2022-09-09

Monitoring stations: 2