Union Lake

On the LakeGrade rubric Union Lake fails the cutoffs — a TSI of 84 and persistent algal pressure put it in the bottom tier. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

A TSI above 70 puts Union Lake in hypereutrophic territory: visible blooms are common, and clarity rarely climbs even in early summer. A maximum depth of just 10 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. The lake's 397 acres and 5.2 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Union Lake ranks 6 of 12 in Rice County — solidly in the upper half of the local distribution.

No invasive species are currently listed at Union Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Union Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. A documented public access point at Union Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 12 times at Union Lake, with a median around Mar 23. 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.