Lake Denoon is a 162-acre lake in the southwestern portion of the City and is also partially located in the Town of Norway. The lake has a glacially formed kettle basin with bottom substrates varying from sands and gravel to muck. An outlet stream on the south end drains to Ke-Nong-Go-Mong (Long) Lake in Racine County.
A cattail island and an extent of cattail shoreline are found on the lake's west end; the remaining lakeshore is mostly developed with residential housing. Lake Denoon provides habitat for the Black Tern, a rare bird species.