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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.8 ft | B |
| Phosphorus | 35.3 µg/L | C |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 20 ft |
| Surface Area | 539 acres |
| Public Access | Yes |
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
Water Quality Trend: → Stable
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.818 m/yr | 7 |
| Phosphorus | ↑ Improving | -9.68 µg/L/yr | 4 |
Recreation & Access
Location
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.
- AShannon LakeVilas County · 2.1 mi · Higher grade (B → A)
- APlum LakeVilas County · 3.4 mi · Higher grade (B → A)
- AStella LakeVilas County · 1.4 mi · Higher grade (B → A)
- AFound LakeVilas County · 1.7 mi · Higher grade (B → A)
- ALake ContentVilas County · 3.2 mi · Higher grade (B → A)
Nearby Lakes in Vilas County
More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Mesotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1993. 5 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
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