Bonnie Lake

Bonnie Lake earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Crow Wing County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

A TSI value of 36 puts Bonnie Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. A maximum depth of 42 ft puts Bonnie Lake in the middle of Minnesota's depth distribution. The lake is compact at 76 acres, with 1.4 miles of shoreline and little volume to buffer nutrient inputs. Bonnie Lake ranks 35 of 120 in Crow Wing County — solidly in the upper half of the local distribution.

Bonnie Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. Bass fishing is part of the appeal: the species list runs to 7, anchored by largemouth and/or smallmouth bass. The lake lacks a documented public access point, so visitor use is limited. The lake has a partial ice record — 6 observed ice-outs, centered near Apr 10. 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.