Little Trout Lake Deep
Vilas County, WisconsinLimited DataOligotrophic
Little Trout Lake Deep 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.
Trophically, Little Trout Lake Deep reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Little Trout Lake Deep is unusually deep for Wisconsin at 98 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 1,007 acres, Little Trout Lake Deep is one of the larger lakes in Vilas County, with partial shoreline records supporting multiple distinct use patterns. Little Trout Lake Deep sits at rank 114 of 202 in Vilas County, in the lower half of the local distribution.
No invasive species are currently listed at Little Trout Lake Deep — 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 2020-07-29. 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 49.2 ft down. Trophic State Index: 21.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 49.2 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 21 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 98 ft |
| Surface Area | 1.0K acres |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Little Trout Lake Deep (14-day solunar calendar)
→ Is it safe to eat fish from Little Trout Lake Deep? (mercury & PFAS guide)
→ Little Trout Lake Deep fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -0.33 µg/L/yr | 2 |
Location
County Ranking
Ranked #114 of 202 lakes in Vilas County
Nearby Lakes in Vilas County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Waukesha County · Clarity: 14.6 ft
Waukesha County · Clarity: 13.8 ft
Walworth County · Clarity: 19 ft
Washington County · Clarity: 12 ft
Kenosha County · Clarity: 10.1 ft
Washington County · Clarity: 12.5 ft
Oligotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 5 stations on file (most recent sample 2003).
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: 2020-07-29
Monitoring stations: 1