Grenlie Lake

On the LakeGrade rubric, Grenlie Lake pulls an A: clarity at 49.2 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.

A TSI value of 21 puts Grenlie Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 40 ft puts Grenlie Lake in the middle of Wisconsin's depth distribution. At 6 acres, Grenlie Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Grenlie Lake sits at rank 18 of 27 in Waupaca County, in the lower half of the local distribution.

An invasive species record — Purple Loosestrife — has been logged at Grenlie Lake; Wisconsin DNR maintains the official infested-waters list. The fishery is bass-led, with 2 documented species across the lake's records. 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.