Flatwater- There is little or no current, and the
river's surface is smooth and unbroken. paddling upstream is
Quickwater- The river
moves fast. Its surface is nearly smooth at high water
levels, but likely to be choppy at medium levels and shallow
at low water levels.
Class I- Fast moving water with a riffles and small
waves. Few or no obstructions, all obvious and easily missed
with little training. Risk to swimmers is slight;
self-rescue is easy.
Class II- Straight forward rapids with wide, clear
channels which are evident without scouting. Occasional
maneuvering may be required, but rocks and medium-sized
waves are easily missed by trained paddlers. Rapids with
waves up to three feet
Class III- Rapids with high, irregular waves which
may be difficult to avoid often capable of swamping an open
canoe. Narrow passages that often require complex
maneuvering in fast current. Good boat control required:
large waves or strainers may be present. Strong eddies and
powerful current effects can be found, particularly on
large-volume rivers. May require scouting from shore.
Group assistance may be required to avoid long swims.
Class IV- Intense, powerful but predictable rapids
requiring precise boat handling in turbulent water.
Depending on the character of the river, it may feature
large, unavoidable waves and holes or constricted passages
demanding fast maneuvers under pressure. A fast,
reliable eddy turn may be needed to initiate maneuvers,
scout rapids or rest. Rapids may require "must" moves
above dangerous hazards. Scouting is necessary
the first time down. Risk of injury to swimmers is
moderate to high, and water conditions may make self rescue
Class V- Extreme.
These runs often exemplify the extremes of difficulty,
unpredictability, and danger. The consequences of
errors are very severe and rescue may be impossible.
For teams of experts only, at favorable water levels, after
close personal inspection and taking all precautions.
(*AMC River Guide