The Whitewater Classification System allows recreational stream and river users to determine the conditions they may expect to encounter while kayaking or canoeing. This system is based primarily on kayaking, but canoers and rafters can apply the information with provisions as summarized at the end of this information.

CLASS I: Easy. Fast moving water with riffles and small waves. Few obstructions, all obvious and easily missed with little training. Risk to swimmers is slight; self-rescue easy.
CLASS II: Novice. Straightforward 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. Swimmers are seldom injured and group assistance, while helpful, is seldom needed.
CLASS III: Intermediate. Rapids with moderate, irregular waves which may be difficult to avoid and which can swamp an open canoe. Complex maneuvers in fast currents and good boat control in tight passages or around ledges are often required; large waves and strainers may be present but are easily avoided. Strong eddies and powerful current effects can be found, particularly on large-volume rivers. Scouting is advisable for inexperienced parties. Injuries while swimming are rare; self-rescue is usually easy but group assistance may be required to avoid long swims.
CLASS IV: Advanced. Intense, powerful but predictable rapids requiring precise boat handling in turbulent water. Depending on the character of the river, 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 difficult. Group assistance for rescue is often essential but requires practice and skill. A strong Eskimo roll is highly recommended.
CLASS V: Expert. Extremely long, obstructed, or very violent rapids which expose a paddler to above average endangerment. Drops may contain large, unavoidable waves and holes or steep congested chutes with complex, demanding routes. Rapids may continue for long distances between pools, demanding a high level of fitness. What eddies exist may be small, turbulent, or difficult to reach. At the high end of the scale, several of these factors may be combined. Scouting is mandatory but often difficult. Swims are dangerous, and rescue is difficult even for experts. A very reliable Eskimo roll, proper equipment, extensive experience, and practiced rescue skills are essential for survival.
CLASS VI: Extreme. One grade more difficult than Class V. 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. This class does not represent drops thought to be unrunnable, but may include rapids which are only occasionally run.

Three additional classifications are included in the above list to reflect water conditions along the river. They are not part of the International Whitewater Classification, but are included to reflect all conditions on the river or inventory status. These classifications are: flatwater; unrunnable; and unclassified.
CLASS 'F': Flatwater. Stationary or slow-moving water with no riffles or waves. Few obstructions, all obvious and easily missed with little or no training. Risk to swimmers is slight; self-rescue easy.
CLASS 'U': Unclassified. No inventory information exists.
CLASS 'N': Unrunnable. Beyond CLASS VI. This class represents drops thought to be unnavigable (eg. dams or very high waterfalls).

The whitewater skill level for canoeing and rafting is not the same as the kayaking skill levels. This difference should be taken into account when determining the potential for non-kayaking activities.

For open canoeing:
NOVICE: has successfully paddled calm lakes, but is inexperienced on moving water.
INTERMEDIATE: experienced on CLASS I moving water and can handle CLASS II.
EXPERT: can maneuver on CLASS III water, and can sometimes successfully run CLASS IV.