River grading uses the International Scale of River Difficulty, which runs from Grade 1 to Grade 6, to describe the difficulty of a section of water. Understanding what those grades mean in practice, and what they do not tell you, is important for anyone planning a paddling trip or leading a group on moving water.
The International Scale
Grade 1 is moving water with a few riffles and small waves, and few or no obstructions. It is not the same as flat water: a lake or a still stretch of river has no rapids at all and is not what Grade 1 describes. Grade 2 introduces some rapids with clear channels and low risk. Grade 3 is where things get more demanding, with irregular waves, some manoeuvring required, and moderate risk if you swim. Grade 4 is serious whitewater requiring advanced skills and scouting. Grade 5 is expert water with high risk. Grade 6 is generally considered unrunnable and is rarely used as a practical category.
What Grade Does Not Tell You
Grade is assessed at a particular water level. A section of river that is Grade 2 in normal flows can become Grade 4 or higher in flood. Water levels in Australian rivers can change rapidly after rain, particularly in the ranges where catchments are steep and runoff is fast. Always check recent water conditions before paddling a river you have not been on recently.
Grade and Group Capability
For groups with minimal paddling experience, flat water or easy Grade 1 moving water is the appropriate starting point. Grade 2 water with mild current is manageable for participants who have basic boat control. Do not mix inexperienced paddlers with Grade 3 or above water. A swim in Grade 3 water can be a significant event for an unprepared paddler.
Scouting Before Running
On unfamiliar rivers, get out and look at any rapid you are not certain about before committing to running it. What looks manageable from a kayak at water level can look very different from the bank. Portaging around a rapid is always an option and is never a failure. The risk-reward calculation changes significantly when you are leading other people.
