Educating yourself about river surfing; and as importantly, learning about a any river wave before you go is paramount. Here is a good vid to start with:
CAUTION: River surfing can be dangerous and even deadly. Your risk tolerance should be based on knowledge, conditions and familiarity of your gear and the place you are surfing. This vid has parts that do NOT apply to all river surfing situations/waves.
Leashes for example: Typical surf ankle leashes are deadly in the river since you will not be able to undo the leash while being held under. So called “quick release” river surf leashes give a sense of false safety since you really only have seconds to realize you are being held under and then figure out how to release the leash.
Colorado has had a near death experience when a river surfer could not locate his quick release on his pfd (board untangled and he survived).
Bend Wave had a fatality that occurred right on/behind the face of the wave while wearing a quick release leash (controversy exists that a foot entrapment was due in part to wearing wearing a quick release knee/calf leash that pulled the surfer into a foothold situation)….
AT RRP, LEASHES ARE NOT NEEDED AND ARE DISCOURAGED BY WARNING SIGNS.
The Denver Surf Report 