Johnson Lake

On the LakeGrade rubric Johnson Lake fails the cutoffs — a TSI of 61 and persistent algal pressure put it in the bottom tier. 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.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. The lake bottoms out at 18 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. At 456 acres, Johnson Lake fits the Minnesota median for monitored lakes, with 10.6 miles of shoreline. Within the 187 graded lakes of St. Louis County, Johnson Lake sits at rank 184, near the bottom of the county list.

No invasive species are currently listed at Johnson Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 11 documented species — a notable draw for Minnesota anglers. A documented public access point at Johnson 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.