Upper Vermillion Lake

Upper Vermillion 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 Upper Vermillion Lake in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. A maximum depth of just 9 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. At 91 acres, Upper Vermillion Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Within the 37 graded lakes of Barron County, Upper Vermillion Lake sits at rank 35, near the bottom of the county list.

Upper Vermillion Lake has at least one documented invasive species (Curly-Leaf Pondweed), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery is bass-led, with 3 documented species across the lake's records. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.