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Fowler Lake

Waukesha County, WisconsinMesotrophic

Fowler Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in 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 50 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. The lake is compact at 97 acres, with partial shoreline records and little volume to buffer nutrient inputs. Among the 45 graded lakes in Waukesha County, Fowler Lake sits at rank 17, above the county median.

Zebra mussel presence at Fowler Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The fishery includes walleye alongside the lake's other 4 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. 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 2026-06-15. 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 14.5 ft. Phosphorus level: 15.6 µg/L. Trophic State Index: 41.

MetricValueGrade
Water Clarity (Secchi Depth)14.5 ftB
Phosphorus15.6 µg/LA
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)41Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth50 ft
Surface Area97 acres
Public AccessYes

Fish Species

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

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

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

Fowler 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.

Grass Carp(since 1990)Rudd(since 1916)

Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.

Water Quality Trend: Stable

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

MetricTrendChange/YearYears
Water Clarity Stable+0.196 m/yr7
Phosphorus Stable-0.19 µg/L/yr6
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Location

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County Ranking

Ranked #17 of 45 lakes in Waukesha County

Nearby Lakes in Waukesha County

State Parks Near Fowler Lake

WI DNR Lake Profile

Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2011. 7 stations on file (most recent sample 2025).

DNR Assessment
Reported
Trophic State Index 35 (oligotrophic) · 5-year average

Fish Species (DNR-rated)

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

Reservoir Info (USACE NID)

Fowler Lake is a man-made reservoir impounded by the Peacock (completed 1840), built primarily for recreation on the OCONOMOWOC; gravity-type dam, 11 ft tall and 150 ft long.

Surface area
78 ac
Normal storage
550 ac-ft
Max storage
630 ac-ft
Drainage area
88 sq mi
Hazard class
Significant
Owner
City of Oconomowoc

Source: USACE National Inventory of Dams, NID ID WI00704 · Operator website

EPA Impairment Status

Fowler Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Nutrients (phosphorus, nitrogen)PCBs

Source: EPA ATTAINS assessment unit WI10001317 · Official waterbody report · Matched by proximity (2.62 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: 2026-06-15

Monitoring stations: 2

Where to stay near Fowler Lake

Compare lakeside cabins, hotels, and vacation rentals near Fowler Lake in Waukesha County, Wisconsin — live availability and prices for your trip.

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