Francis Lake

Francis Lake earns a D — measurements through 2024 show persistent nutrient pressure that limits clarity through the summer. Clarity is the limiting factor — phosphorus is reasonable but suspended particles or algal cells keep water transparency below Minnesota norms.

At a TSI of 63, Francis Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. Francis Lake is a shallow lake at 7 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 269 acres, Francis Lake fits the Minnesota median for monitored lakes, with 3.8 miles of shoreline. Francis Lake sits at rank 14 of 19 in Isanti County, in the lower half of the local distribution.

No invasive species are currently listed at Francis Lake — the lake remains off the Minnesota infested-waters roster. Bass fishing is part of the appeal: the species list runs to 14, anchored by largemouth and/or smallmouth bass. A documented public access point at Francis Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The lake has a partial ice record — 16 observed ice-outs, centered near Apr 11. Multiple sampling years from Minnesota PCA volunteers and partner agencies back the grade, so the letter should hold steady absent a major watershed shift.