Seneca Lake

Seneca Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Wisconsin average. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

At a TSI of 51, Seneca Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. At only 10 ft deep, Seneca Lake is shallow — wind keeps the water column mixed and sediment resuspension drives phosphorus levels harder to manage. The lake is compact at 18 acres, with partial shoreline records and little volume to buffer nutrient inputs. Seneca Lake ranks 183 of 191 in Vilas County — at the lower end of the locally monitored distribution.

Seneca Lake has no invasive species recorded in Wisconsin state databases as of 2022, though prevention practices still apply at all access points. The fishery is bass-led, with 2 documented species across the lake's records. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.