East Thomas Lake

East Thomas Lake sits at a C on the grading scale — not impaired, not pristine, with summer measurements that vary year to year. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Eutrophic conditions are the baseline here: clarity drops noticeably in late summer, and dissolved oxygen near the bottom can become a concern. A maximum depth of 19 ft puts East Thomas Lake in the middle of Minnesota's depth distribution. East Thomas Lake is small — 12 acres alongside 0.6 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Among the 36 graded lakes in Dakota County, East Thomas Lake sits at rank 17, above the county median.

East Thomas Lake has no invasive species recorded in Minnesota state databases as of 2024, though prevention practices still apply at all access points. Walleye are documented at East Thomas Lake, one of 6 fish species on record for the lake. 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.