Thiensville Millpond

On the LakeGrade rubric Thiensville Millpond fails the cutoffs — a TSI of 78 and persistent algal pressure put it in the bottom tier. Clarity, phosphorus, and chlorophyll-a all rate similarly, so there is no obvious single lever to pull on watershed management.

Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. Thiensville Millpond is small — 45 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Within the 9 graded lakes of Ozaukee County, Thiensville Millpond sits at rank 8, near the bottom of the county list.

Thiensville Millpond has no invasive species recorded in Wisconsin state databases as of 2024, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Thiensville Millpond, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.