Tree Lake

Tree Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The lake sits in the mesotrophic zone — the band where most well-managed Wisconsin lakes fall. Tree Lake reaches 33 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 73 acres, Tree Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Within Portage County's 28 graded lakes, Tree Lake ranks 17 — below the local median, though not at the bottom.

An invasive species record — Banded Mystery Snail — has been logged at Tree Lake; Wisconsin DNR maintains the official infested-waters list. The fishery is bass-led, with 3 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.