Little Spider Lake
Vilas County, WisconsinOligotrophic
Little Spider Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.
The lake's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. Little Spider Lake covers 223 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Among the 202 graded lakes in Vilas County, Little Spider Lake sits at rank 63, above the county median.
Little Spider Lake carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. Walleye are documented at Little Spider Lake, one of 5 fish species on record for the lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.
Source: EPA Water Quality Portal sampling records, Wisconsin DNR Surface Water, last sampled 2025-08-25. 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 52.5 ft down. Phosphorus level: 11.5 µg/L. Trophic State Index: 30.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 52.5 ft | A |
| Phosphorus | 11.5 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 30 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 223 acres |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Little Spider Lake (14-day solunar calendar)
→ Is it safe to eat fish from Little Spider Lake? (mercury & PFAS guide)
→ Little Spider Lake fishing regulations (limits, seasons, special rules)
Invasive Species
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.329 m/yr | 6 |
| Phosphorus | → Stable | -0.22 µg/L/yr | 6 |
Location
County Ranking
Ranked #63 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. Monitored by volunteers since 1993. 3 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: 2025-08-25
Monitoring stations: 1