Willmert Lake

Willmert Lake grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Minnesota. 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 just 8 ft means sediment-bound phosphorus releases back into the water column whenever wind stirs the bottom — a classic shallow-lake dynamic. At 335 acres, Willmert Lake fits the Minnesota median for monitored lakes, with 3.3 miles of shoreline. Willmert Lake ranks 4 of 14 in Martin County — solidly in the upper half of the local distribution.

Willmert Lake has no invasive species recorded in Minnesota state databases as of 2025, though prevention practices still apply at all access points. Walleye are documented at Willmert Lake, one of 11 fish species on record for the lake. A documented public access point at Willmert Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.