Big Trade Lake

Big Trade Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. Big Trade Lake reaches 39 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. The lake's 327 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. Within Burnett County's 57 graded lakes, Big Trade Lake ranks 42 — below the local median, though not at the bottom.

Eurasian watermilfoil is established at Big Trade Lake, which can dampen recreational access and pressure the native plant community. Walleye are documented at Big Trade Lake, one of 5 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.