High Quality Content by WIKIPEDIA articles! The Naches River is a tributary of the Yakima River in central Washington in the United States. Beginning as the Little Naches River, it is about 75 miles (121 km) long. After the confluence of the Little Naches and Bumping River the name becomes simply the Naches River. The Naches and its tributaries drain a portion of the eastern side of the Cascade Range, east of Mount Rainier and northeast of Mount Adams. In terms of discharge, the Naches River is the largest tributary of the Yakima River.