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Gilbert Lake

Waushara County, WisconsinMesotrophic

On the LakeGrade rubric, Gilbert Lake pulls an A: clarity at 12.0 ft and 12 µg/L of phosphorus put it in the top bracket for Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. The lake's 65 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. At 139 acres, Gilbert Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Gilbert Lake ranks 15 of 32 in Waushara County — solidly in the upper half of the local distribution.

Gilbert Lake is on the Wisconsin infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. A documented public access point at Gilbert 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 2026-04-13. Grade methodology: LakeGrade methodology.

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Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Good clarity, visible to about 12 ft. Phosphorus level: 11.8 µg/L. Trophic State Index: 41.

MetricValueGrade
Water Clarity (Secchi Depth)12 ftB
Phosphorus11.8 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)41Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth65 ft
Surface Area139 acres
Public AccessYes

Fish Species

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

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

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

Gilbert 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 SnailEurasian Water-MilfoilHybrid Eurasian / Northern Water-MilfoilPurple LoosestrifeZebra Mussel

Water Quality Trend: Improving

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

MetricTrendChange/YearYears
Water Clarity Improving+0.414 m/yr6
Phosphorus Improving-0.45 µg/L/yr6
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #15 of 32 lakes in Waushara County

Nearby Lakes in Waushara County

State Parks Near Gilbert Lake

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1986. 1 station on file (most recent sample 2025).

DNR Assessment
Reported
Trophic State Index 36 (oligotrophic) · 5-year average

Fish Species (DNR-rated)

Largemouth Bass(Common)Smallmouth Bass(Common)Panfish(Present)Northern Pike(Present)Walleye(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: 2026-04-13

Monitoring stations: 1

Where to stay near Gilbert Lake

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