Colorado River Rafting Difficulty Levels
The International Scale of River Difficulty was created by the American Whitewater Association to classify rivers across the globe in terms of difficulty within six categories, or classes. These classes usually change dramatically with the rising and falling of the water levels in early season high water (snowpack melt) and late season low water (lack of snow to melt) and can even vary during the season based from rainfall and other natural causes.
The guide below is merely that: a guide. Every river rafter, kayaker, canoer, stand up paddle boarder, fisherman, and otherwise should prepare themselves properly for each section of river they choose to navigate. Please, understand that this class system has varying degrees of differentiation along each section of river and each individual rapid along with the influence of Mother Nature, which can create unpredictable hazards and sometimes lethal conditions.
River Classification System
Class I – This is the easiest within the whitewater system. The water is mostly flat, slow currents with an occasional wave or two with no severe river features to obstruct the way. The risk to swimmers in these waters is minimal and a self-rescue situation is easily manageable. This classification is considered a nice float in flatwater.
Class II – This is the milder side of whitewater rafting and requires no scouting of the river. The water presents very small rapids spread amongst the flatwater sections with very few river features to obstruct a clear passage. The risk to swimmers in these waters is, again, minimal with a manageable self-rescue and with little to no group assistance needed. This classification is considered a nice float in very small whitewater.
Class III – This is the “middle of the road” when it comes to whitewater rafting in Colorado. Perfect for families and large groups to enjoy time together on the river, the water has multiple, irregular small to medium waves. Present are some river features that force maneuverability with more narrow passages, and usually contain rocks, strainers and strong eddies within the small rapid sections that are easily avoided. The risk to swimmers in these waters is moderate with potential injuries being rare. A self-rescue situation is manageable, but group assistance may be needed to avoid long swims and other injuries to the swimmer. This classification is considered great summertime, splashy whitewater with very little to fret.
Class IV – This is a difficult stretch of whitewater and should only be navigated by a professional guide or an experienced whitewater recreationalist. While predictable, the water has intense, powerful rapid sections with large waves and multiple hazardous river features especially rocks and large holes. The river features are often dangerous and present narrow passages requiring precise river navigation under pressure. Scouting rapid sections is highly recommended as there can be must make moves in specific sections. The risk to swimmers is moderate to high and injury is likely as the water conditions make a self-rescue situation quite difficult. Group assistance is the key to mitigating serious injury and equipment damage/loss. This classification is considered challenging and quite tiring for everyone on the raft.
Class V – This is the extreme level of whitewater rafting in Colorado and is only for the highly experienced paddler and guide. The water is tumultuous with long, violent rapids and several hazardous river features usually close together with little to no break in between. This class requires high fitness levels and even higher skill levels. Here, the steep gradient of the river drops quickly and sometimes changes directions within those drops through tight passages with dangerously frequent river obstacles, including but not limited to unavoidable holes, waves, and other obstructed river features. The risk to the swimmer is dangerous and is very difficult even for the highly trained professional. Self-rescue is very limited and almost always requires group assistance with the proper equipment, experience, and well-practiced rescue skills. This is considered a thrilling, high-intensity whitewater rafting adventure with a very high-risk potential to all involved.
Class VI – This is unrunnable whitewater for the recreationalist boater. Only professional teams of experts should attempt this river classification after close inspection and after taking all precautions. The water presents large waterfalls, unavoidable river features with extreme risk to all involved. The consequences to error are severe and rescue could prove impossible on all levels. This classification is considered life-threatening.