Circle Lake

Circle Lake grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Minnesota. 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.

The hypereutrophic status — TSI 82 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. Circle Lake is a shallow lake at 14 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 838 acres, Circle Lake fits the Minnesota median for monitored lakes, with 9.5 miles of shoreline. Within Rice County's 12 graded lakes, Circle Lake ranks 9 — below the local median, though not at the bottom.

Eurasian watermilfoil has been documented at Circle Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The fishery includes walleye alongside the lake's other 18 documented species — a notable draw for Minnesota anglers. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a partial ice record — 14 observed ice-outs, centered near Mar 29. 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.