Lion's Den Gorge Nature Preserve is a freshwater beach in Ozaukee County, Wisconsin. Across 180 bacteria samples collected between 2021 and 2025 at nearby monitoring stations, it earns a Beach Safety Grade of F — Failing.
About 51% of samples at Lion's Den Gorge Nature Preserve exceeded the EPA Beach Action Value of 235 CFU/100 mL for Escherichia coli — the threshold at which water managers typically post a swimming advisory. In practice that means the safe-swimming limit was frequently crossed here over the monitored period. Bacteria samples exceed the safe-swimming threshold a large share of the time — this beach flags advisories often.
Lion's Den Gorge Nature Preserve was not under a swimming advisory in the most recent EPA snapshot. Conditions can change quickly after heavy rain or high runoff, so it's still worth checking the current advisory the day you go.