Oroville is a city located in the northern bulk of the Okanogan Highlands in north-central Washington, United States. Oroville is a member municiā¦Oroville is a city located in the northern bulk of the Okanogan Highlands in north-central Washington, United States. Oroville is a member municipality of Okanogan County, Washington, situated between Omak and Penticton. The population was 1,795 at the 2020 census.