Yellowstone Lake

Yellowstone Lake grades an F: every scored parameter (clarity and phosphorus) rates poorly, placing it among the most stressed lakes monitored in Wisconsin. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

A TSI above 70 puts Yellowstone Lake in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. Yellowstone Lake is a shallow lake at 14 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. The lake's 453 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 the 3 graded lakes of Lafayette County, Yellowstone Lake sits at rank 3, near the bottom of the county list.

An invasive species record — Curly-Leaf Pondweed — has been logged at Yellowstone Lake; Wisconsin DNR maintains the official infested-waters list. The fishery includes walleye among the lake's 6 documented species — a notable draw for Wisconsin anglers. 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.