The Columbia River Basin spans across multiple states, including Washington, Idaho, and Oregon.

This vast region is primarily drained by the Columbia River, which flows through Washington and Oregon, and also includes parts of Idaho and other neighboring states. The basin covers approximately 258,000 square miles and is vital to the ecosystem and economy of the Pacific Northwest. It supports agriculture, hydropower, wildlife, and fisheries. The Columbia River Basin plays a key role in the region's water management, conservation efforts, and natural resources, making it an important geographical feature for all the states involved.