Three Island Lake

On the LakeGrade scale Three Island Lake grades a B, with clarity at 9.0 ft and 12 µg/L of phosphorus placing it above the Minnesota median. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. Three Island Lake is a shallow lake at 13 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 288 acres, Three Island Lake fits the Minnesota median for monitored lakes, with 7.5 miles of shoreline. Three Island Lake sits at rank 93 of 133 in Cass County, in the lower half of the local distribution.

No invasive species are currently listed at Three Island Lake — the lake remains off the Minnesota infested-waters roster. The fishery is bass-led, with 8 documented species across the lake's records. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.