Long Lake

Long 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.

The lake sits in the mesotrophic zone — the band where most well-managed Minnesota lakes fall. Long Lake is unusually deep for Minnesota at 128 ft, which buffers the lake against summer warming and helps the deep water stay oxygenated. With 1,289 acres of surface and 12.6 miles of shoreline, Long Lake is a large water by Minnesota standards — recreational pressure is spread across a long shoreline. Among the 97 graded lakes in Otter Tail County, Long Lake sits at rank 26, above the county median.

Zebra mussel presence at Long Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The fishery includes walleye alongside the lake's other 16 documented species — a notable draw for Minnesota anglers. 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.