Little Lake Butte des Morts

Little Lake Butte des Morts grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Wisconsin. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. The lake bottoms out at 18 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. With 1,200 acres of surface and partial shoreline records, Little Lake Butte des Morts is a large water by Wisconsin standards — recreational pressure is spread across a long shoreline. Within the 5 graded lakes of Winnebago County, Little Lake Butte des Morts sits at rank 5, near the bottom of the county list.

Little Lake Butte des Morts 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 Little Lake Butte des Morts, one of 7 fish species on record for the lake. A documented public access point at Little Lake Butte des Morts 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.