Sewell Lake

Sewell Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Minnesota 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. At 52 ft of maximum depth, Sewell Lake stratifies reliably through the summer — the hypolimnion stays cooler and clearer than the surface layer suggests. Sewell Lake covers 369 acres alongside 5.6 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within the 97 graded lakes of Otter Tail County, Sewell Lake sits at rank 92, near the bottom of the county list.

Sewell Lake has no invasive species recorded in Minnesota state databases as of 2023, though prevention practices still apply at all access points. The fishery includes walleye among the lake's 13 documented species — a notable draw for Minnesota anglers. A documented public access point at Sewell 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.