Alder Lake

On the LakeGrade rubric, Alder Lake pulls an A: clarity at 13.8 ft and 8 µg/L of phosphorus put it in the top bracket for Minnesota. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Trophically, Alder Lake reads as oligotrophic — nutrient-poor, clear, and ecologically more sensitive to disturbance than richer lakes. Alder Lake is unusually deep for Minnesota at 72 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. The lake's 529 acres and 10.0 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. Alder Lake ranks 38 of 128 in Cook County — solidly in the upper half of the local distribution.

Alder Lake has no invasive species recorded in Minnesota state databases as of 2022, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Alder Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Alder Lake — most use is by shoreline residents and their guests. 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.