Zumwalde Lake

Zumwalde Lake grades an F: every scored parameter (clarity) rates poorly, placing it among the most stressed lakes monitored in Minnesota.

At a TSI of 65, Zumwalde Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. Zumwalde Lake reaches 23 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. The lake's 128 acres and 4.6 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Zumwalde Lake ranks 50 of 55 in Stearns County — at the lower end of the locally monitored distribution.

Zebra mussels have been documented at Zumwalde Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. The fishery includes walleye among the lake's 18 documented species — a notable draw for Minnesota anglers. The lake lacks a documented public access point, so visitor use is limited. 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.