Koosah Falls was a block waterfall just downstream from Sahalie Falls and upstream from Tamolitch Falls (though we didn't get to visit the latter). All of these falls were on the McKenzie River in the Willamette National Forest.
Like Sahalie Falls, this was a pretty easy-to-visit drive-to waterfall. Though we didn't do the one-mile trail that connected this falls with Sahalie Falls, we knew it would've been a pretty naturesque walk along the river as we didn't see very many people do that trail given how easy it was to visit either waterfall by car.
An interpretive sign claimed that this waterfall was 90ft tall, which we also thought this might have been a generous figure (like with Sahalie Falls). And even though signs suggested this falls had a block shape, it became more segmented during our visit as late August was well past the peak flow of early Summer for the McKenzie River.
We did go down an easy trail that took us to a benched overlook where we saw Koosah Falls between some trees though it was never a totally open view as trees on either side of its opening would block parts of the falls. That trail, by the way, also led to the top of the falls though the view from up here wasn't very satisfying.
We drove to this waterfall by taking the Hwy 126 east from Eugene. After about 54 miles, we reached the town of McKenzie Bridge, where we continued driving along Hwy 126. About 20 miles east and north of the town of McKenzie River (or roughly 70 miles east of Eugene), we saw the signposted falls turnoff on the left side of the highway a short distance south of the Sahalie Falls turnoff (6 miles south of US20 and about 5 miles north of Belknap Springs).
For context, the city of Eugene was 111 miles (under 2 hours drive) south of Portland or 168 miles (2.5 hours drive) north of Medford.
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