O'Leary Lake

O'Leary Lake earns an F: 153 µg/L of phosphorus and clarity at 2.6 ft signal heavy nutrient loading from the surrounding watershed. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

At a TSI of 70, O'Leary Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 34 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 31 acres, O'Leary Lake sits below the Minnesota median: a small water where shoreline activity has an outsized effect on water quality. O'Leary Lake ranks 30 of 36 in Dakota County — at the lower end of the locally monitored distribution.

Eurasian watermilfoil is established at O'Leary Lake, which can dampen recreational access and pressure the native plant community. The fishery is bass-led, with 7 documented species across the lake's records. A documented public access point at O'Leary Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 6 observed ice-outs, centered near Mar 31. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.