Oak Lake

Oak Lake pulls a D on the LakeGrade rubric — phosphorus loading and limited clarity hold it below the Minnesota average. 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 in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. A maximum depth of 20 ft puts Oak Lake in the middle of Minnesota's depth distribution. At 459 acres, Oak Lake fits the Minnesota median for monitored lakes, with 4.8 miles of shoreline. Within the 19 graded lakes of Pine County, Oak Lake sits at rank 15, near the bottom of the county list.

No invasive species are currently listed at Oak Lake — the lake remains off the Minnesota infested-waters roster. Walleye are documented at Oak Lake, one of 12 fish species on record for the lake. A documented public access point at Oak Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.