Big Mckenzie Lake

Big Mckenzie Lake sits at the top of the Wisconsin DNR grading rubric with an A, a mark reached by the cleanest lakes in Wisconsin. 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.

A TSI value of 36 puts Big Mckenzie Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. The lake's 71 ft maximum depth is in the upper tier for Wisconsin — deep enough for cold-water fish to find refuge in summer. Big Mckenzie Lake covers 1,129 acres alongside partial shoreline records, large enough that conditions can vary meaningfully between bays. Among the 48 graded lakes in Washburn County, Big Mckenzie Lake sits at rank 13, above the county median.

Zebra mussels have been documented at Big Mckenzie Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye alongside the lake's other 7 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. 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.