Joanis Lake

Joanis Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Portage County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI value of 40 puts Joanis Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake is compact at 23 acres, with partial shoreline records and little volume to buffer nutrient inputs. Within Portage County's 28 graded waters, Joanis Lake sits at rank 7, near the top of the local distribution.

Joanis Lake 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 Joanis Lake, 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.