The John Day River is a tributary of the Columbia River, and is approximately 281 miles (452 km) long. The river is located in northeastern Oregon. There are two rivers in Oregon that bear this name. The other John Day River is a small tributary of the Columbia in Clatsop County.
The river was named for a member of the Astor Expedition that was funded in part by John Jacob Astor and John Day, who wandered lost through this part of Oregon in the winter of 1811–1812. Through its tributaries it drains much of the western side of the Blue Mountains, flowing across the sparsely populated arid part of the state east of the Cascade Range in a northwest zigzag, then entering the Columbia upstream from the Columbia River Gorge. It flows through exceptionally scenic canyons in its upper course, with several significant paleontological sites along its banks. Undammed along its entire length, the river is the second longest free-flowing river in the conterminous United States. Despite the extensive use of its waters for irrigation, its free-flowing course furnishes an exceptional habitat for diverse species, including prolific wild Steelhead runs.
Source Wikipedia (2008)