Johanna Lake

The LakeGrade rubric puts Johanna Lake at a C: clarity at 7.2 ft, 38 µg/L of phosphorus, and a TSI of 53 signal an intermediate trophic state. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake bottoms out at 43 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 212 acres, Johanna Lake fits the Minnesota median for monitored lakes, with 3.0 miles of shoreline. Johanna Lake ranks 15 of 49 in Ramsey County — solidly in the upper half of the local distribution.

Zebra mussels have been documented at Johanna Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Johanna Lake, one of 13 fish species on record for the lake. A documented public access point at Johanna Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 9 times at Johanna Lake, with a median around Apr 5. 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.