Orwell Lake

The LakeGrade rubric puts Orwell Lake at a C: clarity at 4.1 ft, 54 µg/L of phosphorus, and a TSI of 59 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.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. The lake bottoms out at 25 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 608 acres, Orwell Lake fits the Minnesota median for monitored lakes, with 11.7 miles of shoreline. Orwell Lake ranks 86 of 97 in Otter Tail County — at the lower end of the locally monitored distribution.

Zebra mussels have been documented at Orwell Lake, which alters the filter-feeding balance and can paradoxically increase water clarity while disrupting the food web. Walleye are documented at Orwell Lake, one of 17 fish species on record for the lake. A documented public access point at Orwell Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.