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LakeQuality
B

Lost Lake

Vilas County, WisconsinMesotrophic

Lost Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI near 47 places Lost Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. The lake bottoms out at 20 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Lost Lake covers 539 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Lost Lake ranks 190 of 202 in Vilas County — at the lower end of the locally monitored distribution.

Lost Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. 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 2025-10-13. Grade methodology: LakeGrade methodology.

Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Good clarity, visible to about 14.8 ft. Phosphorus level: 35.3 µg/L. Trophic State Index: 47.

MetricValueGrade
Water Clarity (Secchi Depth)14.8 ftB
Phosphorus35.3 µg/LC
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)47Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth20 ft
Surface Area539 acres
Public AccessYes

Fish Species

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

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

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

Lost Lake fishing regulations (limits, seasons, special rules)

Invasive Species

Banded Mystery SnailChinese Mystery SnailCurly-Leaf PondweedEurasian Water-MilfoilRusty Crayfish

Water Quality Trend: Stable

Based on 7 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.818 m/yr7
Phosphorus Improving-9.68 µg/L/yr4
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #190 of 202 lakes in Vilas County

Cleaner Lakes Within 30 Miles

Lost Lake holds Grade B. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Vilas County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1993. 5 stations on file (most recent sample 2025).

DNR Assessment
Fair · Shallow Lowland lake
Trophic State Index 62 (eutrophic) · 5-year average

Fish Species (DNR-rated)

Panfish(Abundant)Musky(Common)Largemouth Bass(Common)Northern Pike(Common)Walleye(Common)

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: 2025-10-13

Monitoring stations: 2