Tonseth Lake

Tonseth Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season.

A TSI near 44 places Tonseth Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. A maximum depth of 27 ft puts Tonseth Lake in the middle of Minnesota's depth distribution. The lake's 149 acres and 3.2 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Tonseth Lake ranks 46 of 97 in Otter Tail County — solidly in the upper half of the local distribution.

No invasive species are currently listed at Tonseth Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Tonseth Lake, one of 12 fish species on record for the lake. The lake lacks a documented public access point, so visitor use is limited. The lake has a long ice-out record — 39 observations on file, with a median ice-out around Apr 15. 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.