Lake Susan

On the LakeGrade rubric, Lake Susan pulls an A: clarity at 26.2 ft and phosphorus readings still being added put it in the top bracket for Wisconsin. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Trophically, Lake Susan reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. The lake bottoms out at 24 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 21 acres, Lake Susan sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Among the 29 graded lakes in Portage County, Lake Susan sits at rank 8, above the county median.

Lake Susan carries an invasive watermilfoil record — boat-launch decontamination and shoreline care matter more here than at uninfested lakes. The state fisheries records do not list documented species for Lake Susan, which usually reflects a lack of formal fisheries survey work rather than an empty lake. 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.