Unidentified falls on the McKenzie River. 💙🍃🕉🌻 The McKenzie River is a 90-mile tributary of the Willamette River in western Oregon. It drains part of the Cascade Range east of Eugene and flows westward into the southernmost end of the Willamette Valley. It is named for Donald McKenzie, a Scottish Canadian fur trader who explored parts of the Pacific Northwest for the Pacific Fur Company in the early 19th century. For about 8,000 years, the McKenzie River has been home to Native Americans. In more recent history, Kalapuya and Molala tribes.