Thompson Lake

Thompson Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Mesotrophic conditions dominate at Thompson Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Thompson Lake reaches 22 ft at its deepest point — typical for Minnesota mid-sized lakes, with seasonal stratification but limited cold-water refuge. Thompson Lake is small — 84 acres alongside 2.1 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Thompson Lake ranks 8 of 24 in Sherburne County — solidly in the upper half of the local distribution.

No invasive species are currently listed at Thompson Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Thompson Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The lake lacks a documented public access point, so visitor use is limited. 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.