Polly Lake

On the LakeGrade scale Polly Lake grades a B, with clarity at 11.0 ft and phosphorus readings still being added placing it above the Minnesota median.

A TSI near 43 places Polly Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. At 95 ft of maximum depth, Polly Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. Polly Lake covers 122 acres alongside 4.5 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Polly Lake ranks 56 of 142 in Lake County — solidly in the upper half of the local distribution.

No invasive species are currently listed at Polly Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Polly Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.