Porcupine Lake

Porcupine Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in 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 34 puts Porcupine Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 20 ft puts Porcupine Lake in the middle of Wisconsin's depth distribution. At 36 acres, Porcupine Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Porcupine Lake ranks 7 of 39 in Florence County, putting it in the upper tier of locally monitored lakes.

Porcupine Lake has at least one documented invasive species (Purple Loosestrife), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Bass fishing is part of the appeal: the species list runs to 2, anchored by largemouth and/or smallmouth bass. 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.