Big Portage Lake

On the LakeGrade rubric, Big Portage Lake pulls an A: clarity at 18.5 ft and 12 µg/L of phosphorus put it in the top bracket for Wisconsin. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

Trophically, Big Portage Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. A maximum depth of 40 ft puts Big Portage Lake in the middle of Wisconsin's depth distribution. At 586 acres, Big Portage Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Big Portage Lake ranks 11 of 191 in Vilas County, putting it in the upper tier of locally monitored lakes.

Big Portage Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. Walleye are documented at Big Portage Lake, one of 4 fish species on record for the lake. A documented public access point at Big Portage Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.