Lake Wildwood, California. For places called Wildwood Lake, see Wildwood Lake (disambiguation). Lake Wildwood is a census-designated place (CDP) in Nevada County, California, United States. The population was 4,991 at the 2010 census, up from 4,868 at the 2000 census. Lake Wildwood is mainly a gated community and news about the CDP is published in a twice a month newspaper, The Wildwood Independent.