Birch Island Lake

On the LakeGrade scale Birch Island Lake grades a B, with clarity at 8.0 ft and 14 µg/L of phosphorus placing it above the Wisconsin median. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

A TSI near 45 places Birch Island Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Birch Island Lake is a shallow lake at 13 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. The lake's 768 acres and partial shoreline records put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Among the 57 graded lakes in Burnett County, Birch Island Lake sits at rank 28, above the county median.

An invasive species record — Chinese Mystery Snail — has been logged at Birch Island Lake; Wisconsin DNR maintains the official infested-waters list. Bass fishing is part of the appeal: the species list runs to 3, 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.