Mann Lake

Mann Lake comes in at a B on the grading rubric — a respectable showing for a Wisconsin lake of its size and depth. High phosphorus is the leading drag on the score — likely from upland agriculture, lawn runoff, or in-lake sediment release.

A TSI near 44 places Mann Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. The lake bottoms out at 18 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 253 acres, Mann Lake fits the Wisconsin median for monitored lakes, with partial shoreline records. Within the 202 graded lakes of Vilas County, Mann Lake sits at rank 175, near the bottom of the county list.

Mann Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. 2 fish species are documented at Mann Lake, a mixed warm-water community typical for Wisconsin lakes of this size. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.