O'Leary Lake

O'Leary Lake comes in at a B on the grading rubric — a respectable showing for a Minnesota lake of its size and depth. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at O'Leary Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. At 52 ft of maximum depth, O'Leary Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. The lake's 202 acres and 2.5 miles of shoreline put it in the mid-range bucket — large enough for varied use, small enough that watershed inputs reach the whole basin. O'Leary Lake ranks 49 of 187 in St. Louis County — solidly in the upper half of the local distribution.

No invasive species are currently listed at O'Leary Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 9 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.