Shell Lake
Washburn County, WisconsinOligotrophic
On the LakeGrade rubric, Shell Lake pulls an A: clarity at 50.9 ft and 15 µg/L of phosphorus put it in the top bracket for 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.
Trophically, Shell Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Shell Lake reaches 36 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. With 2,513 acres of surface and partial shoreline records, Shell Lake is a large water by Wisconsin standards — recreational pressure is spread across a long shoreline. Among the 48 graded lakes in Washburn County, Shell Lake sits at rank 20, above the county median.
Shell Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Walleye are documented at Shell Lake, one of 6 fish species on record for the lake. A documented public access point at Shell Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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 2025-09-26. 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 50.9 ft down. Phosphorus level: 15.2 µg/L. Trophic State Index: 32.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 50.9 ft | A |
| Phosphorus | 15.2 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 32 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 36 ft |
| Surface Area | 2.5K acres |
| Public Access | Yes |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Shell Lake (14-day solunar calendar)
→ Is it safe to eat fish from Shell Lake? (mercury & PFAS guide)
→ Shell 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 | → Stable | +0.272 m/yr | 7 |
| Phosphorus | ↓ Declining | +2.98 µg/L/yr | 5 |
Recreation & Access
Location
County Ranking
Ranked #20 of 48 lakes in Washburn County
Nearby Lakes in Washburn 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 1988. 8 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: 2025-09-26
Monitoring stations: 1