Pewaukee Lake

On the LakeGrade rubric, Pewaukee Lake pulls an A: clarity at 23.0 ft and phosphorus readings still being added 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's low TSI puts it in oligotrophic territory — the cleanest of the four trophic classes, but also the most vulnerable to nutrient-driven shifts. The lake bottoms out at 45 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Pewaukee Lake covers 2,437 acres alongside partial shoreline records, large enough that conditions can vary meaningfully between bays. Pewaukee Lake ranks 22 of 48 in Waukesha County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Pewaukee Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. A documented public access point at Pewaukee Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.