Big Twin Lake

On the LakeGrade scale Big Twin Lake grades a B, with clarity readings still being added and 28 µg/L of phosphorus placing it above the Wisconsin median. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

At a TSI of 52, Big Twin Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. A maximum depth of just 13 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. At 93 acres, Big Twin Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Big Twin Lake ranks 25 of 32 in Waushara County — at the lower end of the locally monitored distribution.

Eurasian watermilfoil has been documented at Big Twin Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The fishery is bass-led, with 3 documented species across the lake's records. A documented public access point at Big Twin 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.