Quarter Line Lake

Quarter Line Lake earns a D — measurements through 2023 show persistent nutrient pressure that limits clarity through the summer. 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.

At a TSI of 55, Quarter Line Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. A maximum depth of 22 ft puts Quarter Line Lake in the middle of Minnesota's depth distribution. At 20 acres, Quarter Line Lake sits below the Minnesota median: a small water where shoreline activity has an outsized effect on water quality. Within the 187 graded lakes of St. Louis County, Quarter Line Lake sits at rank 151, near the bottom of the county list.

Quarter Line Lake has no invasive species recorded in Minnesota state databases as of 2023, though prevention practices still apply at all access points. Bass fishing is part of the appeal: the species list runs to 3, anchored by largemouth and/or smallmouth bass. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.