Sanburn Lake

Sanburn Lake sits at the top of the Minnesota PCA grading rubric with an A, a mark reached by the cleanest lakes 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.

A TSI value of 35 puts Sanburn Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Sanburn Lake reaches 48 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 220 acres, Sanburn Lake fits the Minnesota median for monitored lakes, with 2.5 miles of shoreline. Sanburn Lake ranks 18 of 133 in Cass County, putting it in the upper tier of locally monitored lakes.

No invasive species are currently listed at Sanburn Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Sanburn Lake, one of 12 fish species on record for the lake. 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.