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Squash Lake

Oneida County, WisconsinOligotrophic

Squash Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Oneida County. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Trophically, Squash Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Squash Lake is unusually deep for Wisconsin at 74 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 398 acres, Squash Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Within Oneida County's 134 graded waters, Squash Lake sits at rank 5, near the top of the local distribution.

Eurasian watermilfoil is established at Squash Lake, which can dampen recreational access and pressure the native plant community. The fishery includes walleye alongside the lake's other 6 documented species — a notable draw for Wisconsin anglers. 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 2026-04-25. 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 17.4 ft down. Phosphorus level: 9.6 µg/L. Trophic State Index: 36.

MetricValueGrade
Water Clarity (Secchi Depth)17.4 ftA
Phosphorus9.6 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)36Oligotrophic

Low nutrients, clear water, excellent for swimming

Lake Details

CharacteristicValue
Maximum Depth74 ft
Surface Area398 acres
Public AccessYes

Fish Species

Click a species to see every graded lake where it is documented.

→ Best fishing times for Squash Lake (14-day solunar calendar)

→ Is it safe to eat fish from Squash Lake? (mercury & PFAS guide)

Squash 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.

Banded Mystery SnailChinese Mystery SnailEurasian Water-MilfoilRusty Crayfish

Water Quality Trend: Stable

Based on 6 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.747 m/yr6
Phosphorus Improving-0.35 µg/L/yr6
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #5 of 134 lakes in Oneida County

Nearby Lakes in Oneida County

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1989. 2 stations on file (most recent sample 2025).

DNR Assessment
Excellent · Deep Seepage lake
Trophic State Index 37 (oligotrophic) · 5-year average

Fish Species (DNR-rated)

Panfish(Common)Smallmouth Bass(Common)Northern Pike(Common)Walleye(Common)Largemouth Bass(Present)Trout(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

Public boat-access points from the USGS National Boat Ramps inventory

Most recent sample: 2026-04-25

Monitoring stations: 1

Where to stay near Squash Lake

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