Heidmann Lake

Heidmann Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Kewaunee County. 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.

Trophically, Heidmann Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. The lake bottoms out at 34 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 23 acres, Heidmann Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Heidmann Lake ranks 1 of 5 in Kewaunee County, putting it in the upper tier of locally monitored lakes.

Eurasian watermilfoil is established at Heidmann Lake, which can dampen recreational access and pressure the native plant community. The fishery is bass-led, with 2 documented species across the lake's records. 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.