Fort Okanogan, Trade outpost and heritage site in Okanogan County, United States.

Fort Okanogan was a fur-trading post at the confluence of the Okanogan and Columbia Rivers, founded in 1811 for John Jacob Astor's Pacific Fur Company. Its original site was flooded in 1967 by Lake Pateros, the reservoir behind Wells Dam, so nothing of the stockade remains. Near the old fort, the state opened a small Fort Okanogan Interpretive Center, which Washington handed over to the Colville Tribes in 2011.

The fort was established in 1811 as the first American settlement in Washington and became a crucial trading hub for the Pacific Fur Company and later the Hudson's Bay Company. It grew into a central gathering point where traders and Indigenous peoples conducted business together.

The fort's name comes from the Okanogan people, whose leaders met Pacific Fur Company officers on 31 October 1811 and agreed to keep friendly relations, take part in beaver trapping, guard the station and keep its workers fed. The site is now managed by the Colville tribes, who took over the interpretive center and state park in 2011.

The fort itself no longer stands: its site was submerged in 1967 by Lake Pateros behind Wells Dam. The Fort Okanogan Interpretive Center, run by the Confederated Tribes of the Colville Reservation since Washington State gave up the park in 2011, holds the museum exhibits. Check current opening arrangements before traveling, as state funding ended.

The original fort site now sits underwater in Lake Pateros, created in 1967 when Wells Dam was built on the Columbia River. This inundation shows how modern development reshaped the physical traces of early settlement history.