Round Island Lake

Round Island Lake earns a C — middle-of-the-pack water quality, with one or two parameters dragging the average down from a stronger grade. 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. Round Island Lake is a shallow lake at 4 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. The lake is compact at 55 acres, with 1.6 miles of shoreline and little volume to buffer nutrient inputs. Within the 142 graded lakes of Lake County, Round Island Lake sits at rank 117, near the bottom of the county list.

No invasive species are currently listed at Round Island Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Round Island Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. 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.