Tyson Lake

Tyson Lake earns a D — measurements through 2024 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.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. Tyson Lake is a shallow lake at 8 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. At 166 acres, Tyson Lake fits the Minnesota median for monitored lakes, with 3.3 miles of shoreline. Within Yellow Medicine County's 5 graded lakes, Tyson Lake ranks 3 — below the local median, though not at the bottom.

No invasive species are currently listed at Tyson Lake — the lake remains off the Minnesota infested-waters roster. The fishery includes walleye alongside the lake's other 8 documented species — a notable draw for Minnesota anglers. A documented public access point at Tyson Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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.