Three Island Lake

Three Island Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes in Minnesota. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. 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 729 acres, Three Island Lake fits the Minnesota median for monitored lakes, with 10.4 miles of shoreline. Among the 86 graded lakes in Beltrami County, Three Island Lake sits at rank 40, above the county median.

Three Island Lake is on the watch list for starry stonewort, an invasive macroalga that is difficult to control once established. The fishery includes walleye alongside the lake's other 17 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 — 8 observed ice-outs, centered near Apr 23. 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.