Rapid Rating


River Mileage

About Boulder Bend Rapid

Class III, Class IV >13,000 CFS. At most levels (6,500 CFS and up), the start of Boulder Bend Proper is marked by a hole river center known as the “Aguirre ” or “Flapper Wave” that grows in proportion to the flow. It has a tendency to flip boats and send former passengers and gear to the center of the river, towards a pile of boulders collectively known as “Sieve Rock”. In recent years, there has been a log in the sieve, though it changes out during high water events. Stay to the right of the Flapper Wave and continue down the right side (inside) of the bend. Once past the Sieve Rock, the rapid opens up and different read-and-run lines develop depending on the flow. High flows (>8,000 CFS) create stompy holes left of center culminating in Elevator Shaft – a massive pourover at the bottom left of the rapid before the river makes yet another right hand bend. At flows above 13,000 CFS, Douglas North claims that Boulder Bend should be treated as a Class IV rapid. The current slows a bit as the river bends right and funnels into a Class II wavetrain. Stay in the train to avoid the large, slow eddies on either side.