St. Olaf Lake

On the scoring rubric St. Olaf Lake grades a D: clarity at 5.0 ft and phosphorus readings still being added keep it in the lower bracket for Waseca County. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

At a TSI of 54, St. Olaf Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 33 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. St. Olaf Lake is small — 91 acres alongside 1.6 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Among the 6 graded lakes in Waseca County, St. Olaf Lake sits at rank 2, above the county median.

No invasive species are currently listed at St. Olaf Lake — the lake remains off the Minnesota infested-waters roster. Bass fishing is part of the appeal: the species list runs to 11, anchored by largemouth and/or smallmouth bass. A documented public access point at St. Olaf Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 15 observed ice-outs, centered near Mar 31. 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.