Bonney Lake is a city in Pierce County, Washington. The population was 22,487 at the time of the 2020 census. Bonney Lake was incorporateā¦Bonney Lake is a city in Pierce County, Washington. The population was 22,487 at the time of the 2020 census. Bonney Lake was incorporated as a town on February 28, 1949, after the establishment of a co-op venture to bring electricity and tap water service to local residents. Several unsuccessful attempts were made to disincorporate the town from 1952 to 1972.