Petenwell Flowage Lake

Petenwell Flowage Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

At a TSI of 58, Petenwell Flowage Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 44 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. With 23,173 acres of surface and partial shoreline records, Petenwell Flowage Lake is a large water by Wisconsin standards — recreational pressure is spread across a long shoreline. Petenwell Flowage Lake ranks 1 of 2 in Juneau County — solidly in the upper half of the local distribution.

Petenwell Flowage 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. Walleye are documented at Petenwell Flowage Lake, one of 8 fish species on record for the lake. 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.