Middle Eau Claire Lake

On the LakeGrade rubric, Middle Eau Claire Lake pulls an A: clarity at 17.3 ft and 13 µg/L of phosphorus put it in the top bracket for Wisconsin. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

A TSI value of 38 puts Middle Eau Claire Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Middle Eau Claire Lake is unusually deep for Wisconsin at 66 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. At 880 acres, Middle Eau Claire Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Middle Eau Claire Lake ranks 10 of 52 in Bayfield County, putting it in the upper tier of locally monitored lakes.

Middle Eau Claire 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 Middle Eau Claire Lake, one of 6 fish species on record for the lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.