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. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

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.

Zebra mussel presence at Marion Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The fishery includes walleye alongside the lake's other 14 documented species — a notable draw for Minnesota anglers. A documented public access point at Marion Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 14 observed ice-outs, centered near Mar 30. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.