Perch Lake
Oneida County, WisconsinMesotrophic
Perch Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Oneida County. 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.
Mesotrophic conditions dominate at Perch Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Perch Lake is unusually deep for Wisconsin at 56 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake is compact at 34 acres, with partial shoreline records and little volume to buffer nutrient inputs. Perch Lake ranks 8 of 134 in Oneida County, putting it in the upper tier of locally monitored lakes.
Perch Lake has at least one documented invasive species (Chinese Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Bass fishing is part of the appeal: the species list runs to 2, anchored by largemouth and/or smallmouth bass. 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 2025-08-17. Grade methodology: LakeGrade methodology.
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 15 ft down. Phosphorus level: 14.5 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 15 ft | A |
| Phosphorus | 14.5 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 56 ft |
| Surface Area | 34 acres |
| Public Access | Yes |
Fish Species
Click a species to see every graded lake where it is documented.
→ Best fishing times for Perch Lake (14-day solunar calendar)
→ Is it safe to eat fish from Perch Lake? (mercury & PFAS guide)
→ Perch 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 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.082 m/yr | 7 |
| Phosphorus | ↓ Declining | +0.93 µg/L/yr | 6 |
Recreation & Access
Location
County Ranking
Ranked #8 of 134 lakes in Oneida County
Nearby Lakes in Oneida 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
Mesotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2002. 1 station on file (most recent sample 2025).
Fish Species (DNR-rated)
EPA Impairment Status
Perch Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit WI10007349 · Official waterbody report · Matched by proximity (1.66 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Fish and recreation data from Wisconsin DNR Lakes
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2025-08-17
Monitoring stations: 1
Where to stay near Perch Lake
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