Soap Lake is a city in Grant County, Washington, on the shores of Soap Lake. The population was 1,733 at the 2000 census. In 2002, the city announced preliminary plans to construct the world's largest lava lamp (60 feet in height) as a tourist attraction. Soap Lake was officially incorporated on June 9, 1919. The choosing of the town’s name ended the battle between two rival factions. One group had platted a town site and called it Siloam in 1905; while another faction named their town-to-be Cottage City on 1908.