Willmar Lake

Willmar Lake earns a D — measurements through 2022 show persistent nutrient pressure that limits clarity through the summer. 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. Willmar Lake is a shallow lake at 14 ft maximum depth, which means it warms quickly, mixes constantly, and amplifies nutrient inputs. Willmar Lake covers 636 acres alongside 7.9 miles of shoreline — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Willmar Lake sits at rank 22 of 35 in Kandiyohi County, in the lower half of the local distribution.

Zebra mussel presence at Willmar Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. Walleye are documented at Willmar Lake, one of 18 fish species on record for the lake. A documented public access point at Willmar Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 7 times at Willmar Lake, with a median around Mar 28. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.