The Okanogan River (known as the Okanagan River in Canada) is a tributary of the Columbia River, approximately 115 mi (185 km) long, in southern British Columbia and north central Washington. It drains a scenic plateau region called the Okanagan Country east of the Cascade Range and north and west of the Columbia, and also the Okanagan region of British Columbia. The Canadian portion of the river has been channelized since the mid-1950s. Source: Wikipedia