Marion Lake

The LakeGrade rubric puts Marion Lake at a C: clarity at 7.0 ft, phosphorus readings still being added, and a TSI of 49 signal an intermediate trophic state.

A TSI near 49 places Marion Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. Marion Lake reaches 21 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Marion Lake covers 530 acres alongside 10.2 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Marion Lake ranks 12 of 36 in Dakota County — solidly in the upper half of the local distribution.

Marion Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. Walleye are documented at Marion Lake, one of 14 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 14 observed ice-outs, centered near Mar 30. 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.