Shadow Lake
Oconto County, WisconsinMesotrophic
Shadow 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.
The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake is compact at 24 acres, with partial shoreline records and little volume to buffer nutrient inputs. Among the 66 graded lakes in Oconto County, Shadow Lake sits at rank 17, above the county median.
No invasive species are currently listed at Shadow Lake — the lake remains off the Wisconsin infested-waters roster. Bass fishing is part of the appeal: the species list runs to 3, anchored by largemouth and/or smallmouth bass. Public access is available — the lake is on the Wisconsin DNR public-access list. 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 2023-08-23. 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 19.7 ft down. Phosphorus level: 18 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 19.7 ft | A |
| Phosphorus | 18 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 24 acres |
| Public Access | Yes |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Shadow Lake (14-day solunar calendar)
→ Is it safe to eat fish from Shadow Lake? (mercury & PFAS guide)
→ Shadow Lake fishing regulations (limits, seasons, special rules)
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -2.5 m/yr | 4 |
| Phosphorus | ↓ Declining | +1.9 µg/L/yr | 2 |
Recreation & Access
Location
County Ranking
Ranked #17 of 66 lakes in Oconto County
Nearby Lakes in Oconto County
More Wisconsin Lake Rankings
State Parks Near Shadow Lake
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
Mesotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. 1 station on file (most recent sample 2023).
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: 2023-08-23
Monitoring stations: 1