Okauchee Lake
Waukesha County, WisconsinMesotrophic
Okauchee Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. 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.
The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. At 90 ft of maximum depth, Okauchee Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. Okauchee Lake covers 1,210 acres alongside partial shoreline records, large enough that conditions can vary meaningfully between bays. Okauchee Lake sits at rank 33 of 48 in Waukesha County, in the lower half of the local distribution.
Zebra mussel presence at Okauchee 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 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 2022-09-26. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Good clarity, visible to about 11.3 ft. Phosphorus level: 18 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.3 ft | B |
| Phosphorus | 18 µg/L | A |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 90 ft |
| Surface Area | 1.2K acres |
| Public Access | Yes |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Okauchee Lake (14-day solunar calendar)
→ Is it safe to eat fish from Okauchee Lake? (mercury & PFAS guide)
→ Okauchee Lake fishing regulations (limits, seasons, special rules)
Invasive Species
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.912 m/yr | 3 |
| Phosphorus | ↑ Improving | -1.13 µg/L/yr | 3 |
Recreation & Access
Location
County Ranking
Ranked #33 of 48 lakes in Waukesha County
Nearby Lakes in Waukesha County
More Wisconsin Lake Rankings
State Parks Near Okauchee Lake
Other Grade A Lakes in Wisconsin
Walworth County · Clarity: 19 ft
Washington County · Clarity: 12 ft
Kenosha County · Clarity: 10.1 ft
Washington County · Clarity: 12.5 ft
Walworth County · Clarity: 10.8 ft
Walworth County · Clarity: 11 ft
Mesotrophic Lakes in Wisconsin
WI DNR Lake Profile
Authoritative data from the Wisconsin DNR LakePages. Monitored by volunteers since 1995. 17 stations on file (most recent sample 2025).
Fish Species (DNR-rated)
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
Most recent sample: 2022-09-26
Monitoring stations: 1