Umpqua River, North Fork: Tigard to Willamette River Professional Review and Guide
"The water on the North Umpqua is magical. Its blue hue and clarity are due to underlying lava rock, which filters much of the water before it reaches the river. Numerous springs feed the river year-round for ample flows into summer. The upper river corridor is narrow, but the lower river widens, exposing smaller rock ledges and narrow passages at low flows.
Paddlers in small craft can negotiate the entire river year-round, though rafts are best in all seasons except late summer. Rapids are short, steep, pool-drop encounters along the upper and central river, gradually easing in difficulty and spreading out on the lower river. Exceptions are Deadline Falls and The Narrows. Both of these Class V areas on the lower river require a scout. Most boaters opt to portage these obstacles."