Big Round Deep Hole South Lake

Big Round Deep Hole South Lake earns a D — measurements through 2023 show persistent nutrient pressure that limits clarity through the summer. 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.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. A maximum depth of 17 ft puts Big Round Deep Hole South Lake in the middle of Wisconsin's depth distribution. At 1,014 acres, Big Round Deep Hole South Lake is one of the larger lakes in Polk County, with partial shoreline records supporting multiple distinct use patterns. Within the 74 graded lakes of Polk County, Big Round Deep Hole South Lake sits at rank 65, near the bottom of the county list.

Big Round Deep Hole South 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 Round Deep Hole South Lake, one of 5 fish species on record for the lake. A documented public access point at Big Round Deep Hole South Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.