The Regional District of Okanagan-Similkameen (RDOS) is in southern British Columbia, adjacent to the U.S. state of Washington. It is bounded by Fraser Valley Regional District to the west, Thompson-Nicola Regional District and Regional District of Central Okanagan to the north, Regional District of Kootenay Boundary to the east, and by Okanogan County, Washington to the south. At the 2011 census the population was 80,742. The district covers a land area of . The administrative offices are in the City of Penticton.