The Columbia just below the confluence of the Columbia and the Spokane River. "The Columbia River is the largest river in the Pacific Northwest region of North America. It stretches from British Columbia through Washington state, forming much of the border between Washington and Oregon before emptying into the Pacific Ocean. The river is 1,243 miles (2,000 km) long. Measured by the volume of its flow, the Columbia is the largest river flowing into the Pacific from North America and is the fourth-largest river in the U.S. The river's heavy flow, and its large elevation drop over a relatively short distance, give it tremendous potential for the generation of electricity. It is the largest hydroelectric power producing river in North America with fourteen hydroelectric dams in the U.S. and Canada, and many more on various tributaries.