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.
Watch Fowler Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
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.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.5 ft | B |
| Phosphorus | 15.6 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 50 ft |
| Surface Area | 97 acres |
| Public Access | Yes |
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.
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).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.196 m/yr | 7 |
| Phosphorus | → Stable | -0.19 µg/L/yr | 6 |
Recreation & Access
Location
County Ranking
Ranked #17 of 45 lakes in Waukesha County
Nearby Lakes in Waukesha County
More Wisconsin Lake Rankings
State Parks Near Fowler Lake
Other Grade A Lakes in Wisconsin
Washington County · Clarity: 11.8 ft
Washington County · Clarity: 12.6 ft
Walworth County · Clarity: 11 ft
Walworth County · Clarity: 20.2 ft
Kenosha County · Clarity: 10 ft
Sawyer County · Clarity: 12.2 ft
Mesotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 2011. 7 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
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
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.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.