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LakeQuality
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Little Trout Lake

Vilas County, WisconsinLimited DataMesotrophic

Little Trout Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. Little Trout Lake is unusually deep for Wisconsin at 98 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. With 1,007 acres of surface and partial shoreline records, Little Trout Lake is a large water by Wisconsin standards — recreational pressure is spread across a long shoreline. Little Trout Lake sits at rank 149 of 202 in Vilas County, in the lower half of the local distribution.

No invasive species are currently listed at Little Trout Lake — the lake remains off the Wisconsin infested-waters roster. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Wisconsin anglers. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.

Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2024-07-24. Grade methodology: LakeGrade methodology.

Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

No clarity data. Phosphorus level: 12.5 µg/L. Trophic State Index: 41.

MetricValueGrade
Water Clarity (Secchi Depth)No data
Phosphorus12.5 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)41Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth98 ft
Surface Area1.0K acres

Fish Species

Click a species to see all Wisconsin and Minnesota lakes where it is found.

→ Best fishing times for Little Trout Lake (14-day solunar calendar)

→ Is it safe to eat fish from Little Trout Lake? (mercury & PFAS guide)

Little Trout Lake fishing regulations (limits, seasons, special rules)

Water Quality Trend: Improving

Based on 3 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Phosphorus Improving-0.33 µg/L/yr2
See year-by-year chart →

Location

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County Ranking

Ranked #149 of 202 lakes in Vilas County

Nearby Lakes in Vilas County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. 5 stations on file (most recent sample 2003).

Fish Species (DNR-rated)

Musky(Common)Smallmouth Bass(Common)Walleye(Common)Panfish(Present)Largemouth Bass(Present)Trout(Present)

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Fish and recreation data from Wisconsin DNR Lakes

Most recent sample: 2024-07-24

Monitoring stations: 1