Douglas County is a county located in the U.S. state of Washington. As of the 2020 census, its population was 42,938. The county seat is Waterville, while its largest settlement is East Wenatchee. The county was created out of Lincoln County on November 28, 1883 and is named for American statesman Stephen A. Douglas.

Waterville is a town in and the county seat of Douglas County, Washington, United States which is known for its wheat industry. As a part of Douglas County, it is part of the Wenatchee-East Wenatchee metropolitan area. The population was 1,134 at the 2020 census.