Long Lake

On the LakeGrade scale Long Lake grades a B, with clarity at 13.5 ft and phosphorus readings still being added placing it above the Minnesota median. 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 40 puts Long Lake in the oligotrophic range, where biological productivity stays low and the water column remains clear. Long Lake reaches 33 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 150 acres, Long Lake fits the Minnesota median for monitored lakes, with 4.0 miles of shoreline. Among the 187 graded lakes in St. Louis County, Long Lake sits at rank 51, above the county median.

Long Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. The fishery includes walleye alongside the lake's other 8 documented species — a notable draw for Minnesota anglers. The lake lacks a documented public access point, so visitor use is limited. Ice-out has been recorded 15 times at Long Lake, with a median around Apr 21. 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.