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.

Mesotrophic conditions dominate at Porcupine Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. 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. Among the 39 graded lakes in Florence County, Porcupine Lake sits at rank 11, above the county median.

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.