Oconomowoc Lake is a village in Waukesha County, Wisconsin, United States. Located just outside the City of Oconomowoc, the village includes the residential area encircling Oconomowoc Lake. Around the turn of the 20th century, the area become known as a summer retreat for wealthy residents of Milwaukee and Chicago. The population was 566 at the …Oconomowoc Lake is a village in Waukesha County, Wisconsin, United States. Located just outside the City of Oconomowoc, the village includes the residential area encircling Oconomowoc Lake. Around the turn of the 20th century, the area become known as a summer retreat for wealthy residents of Milwaukee and Chicago. The population was 566 at the 2020 census, and has remained one of the wealthiest jurisdictions in the state of Wisconsin.