A tributary of the Columbia River, the Okanagan begins near Armstrong, B.C. From there, it runs approximately 185 kilometres through southern B.C. and northern Washington, connecting with the Similkaneen River near the Canada-U.S. border.

Much of the watershed falls in the rain shadow of the Coast and Cascade mountains. This desert-like region has the lowest per person water supply in Canada, adding to the importance of these rivers.

Despite the dryness, the watershed supports award-winning wineries and fruit orchards. Meanwhile, beautiful vistas and warm summers draw an increasing number of developers and tourists each year, making this one of the fastest-growing areas in the country.

The area is home to diverse and unique wildlife, including eight species of vertebrates and 28 species of invertebrates found nowhere else in Canada. The rivers also serve as key habitat for sockeye salmon and an important stop for many species of migratory birds.