Osnuhsa Lake

Osnuhsa Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. High phosphorus is the leading drag on the score — likely from upland agriculture, lawn runoff, or in-lake sediment release.

Mesotrophic conditions dominate at Osnuhsa Lake: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. Osnuhsa Lake is small — 6 acres alongside partial shoreline records — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Osnuhsa Lake ranks 3 of 3 in Brown County — at the lower end of the locally monitored distribution.

Osnuhsa Lake has no invasive species recorded in Wisconsin state databases as of 2025, though prevention practices still apply at all access points. The state fisheries records do not list documented species for Osnuhsa Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. The grade is supported by multiple sampling years from the Wisconsin DNR Citizen Lake Monitoring Network, giving the letter a reasonably stable foundation.