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LakeQuality
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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.

MetricValueGrade
Water Clarity (Secchi Depth)50.9 ftA
Phosphorus15.2 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)32Oligotrophic

Low nutrients, clear water, excellent for swimming

Lake Details

CharacteristicValue
Maximum Depth36 ft
Surface Area2.5K acres
Public AccessYes

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

Banded Mystery SnailChinese Mystery SnailCurly-Leaf PondweedPurple Loosestrife

Water Quality Trend: Declining

Based on 7 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Stable+0.272 m/yr7
Phosphorus Declining+2.98 µg/L/yr5
See year-by-year chart →

Recreation & Access

5
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #20 of 48 lakes in Washburn County

Nearby Lakes in Washburn County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1988. 8 stations on file (most recent sample 2025).

DNR Assessment
Excellent · Shallow Seepage lake
Trophic State Index 44 (mesotrophic) · 5-year average

Fish Species (DNR-rated)

Smallmouth Bass(Abundant)Walleye(Abundant)Musky(Common)Panfish(Common)Largemouth Bass(Present)Northern Pike(Present)

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