Koosah Falls, also known as Middle Falls, is the second of the three major waterfalls on the McKenzie River in the heart of the Willamette National Forest in Linn County, in the U.S. state of Oregon. The waterfall is notable for its main drop of 64 feet that plunges into a considerable pool, south of Santiam Pass. Koosah Falls is located southeast of Salem, Oregon, northeast of Eugene, Oregon and west of Mt. Washington.