First Black Lake

First Black Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI near 49 places First Black Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. A maximum depth of 19 ft puts First Black Lake in the middle of Wisconsin's depth distribution. At 23 acres, First Black Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Within the 34 graded lakes of Iron County, First Black Lake sits at rank 33, near the bottom of the county list.

No invasive species are currently listed at First Black Lake — the lake remains off the Wisconsin infested-waters roster. Walleye are documented at First Black Lake, one of 5 fish species on record for the lake. 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.