Middle Sugarbush Lake
Vilas County, WisconsinOligotrophic
Middle Sugarbush Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.
A TSI value of 40 puts Middle Sugarbush Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 57 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. Middle Sugarbush Lake covers 254 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Middle Sugarbush Lake ranks 70 of 191 in Vilas County — solidly in the upper half of the local distribution.
An invasive species record — Rusty Crayfish — has been logged at Middle Sugarbush Lake; Wisconsin DNR maintains the official infested-waters list. Walleye are documented at Middle Sugarbush Lake, one of 6 fish species on record for the lake. 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 2025-09-01. Grade methodology: LakeGrade methodology.
Watch Middle Sugarbush Lake water quality
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 14.5 ft. Phosphorus level: 13 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.5 ft | B |
| Phosphorus | 13 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 57 ft |
| Surface Area | 254 acres |
Fish Species
Click a species to see every graded lake where it is documented.
→ Best fishing times for Middle Sugarbush Lake (14-day solunar calendar)
→ Is it safe to eat fish from Middle Sugarbush Lake? (mercury & PFAS guide)
→ Middle Sugarbush Lake fishing regulations (limits, seasons, special rules)
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.6 m/yr | 5 |
| Phosphorus | ↓ Declining | +0.68 µg/L/yr | 5 |
Location
County Ranking
Ranked #70 of 191 lakes in Vilas County
Nearby Lakes in Vilas County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Washington County · Clarity: 11.8 ft
Washington County · Clarity: 12.6 ft
Walworth County · Clarity: 11 ft
Waukesha County · Clarity: 11.3 ft
Walworth County · Clarity: 20.2 ft
Kenosha County · Clarity: 10 ft
Oligotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 2 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: 2025-09-01
Monitoring stations: 1
Where to stay near Middle Sugarbush Lake
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