Where grades are given in the waterway descriptions, they refer to the table below. However, the grade given for a stretch of water refers to normal conditions, and the grade may be one or more levels higher when the river is high. Common river hazards are described, but other hazards can occur, and after high winds or water levels, trees and debris can be present in the river.

 

Placid	Still or very slow-moving water (e.g. canals, small lakes and lowland rivers). Simple to negotiate, but hazards such as locks, weirs and motorised traffic may be present on this type of waterway and need to be treated with caution. In windy conditions, substantial waves may form on lakes and larger rivers, and it can be difficult to paddle on open water. Placid rivers can become fast-flowing with high water levels, and trees/fences etc can be hazardous.
Grade I	Moving water with small waves, meanders and occasional simple rapids. Hazards on this grade of water are mostly trees, particularly on bends and/or in high water levels, and stationary objects such as bridges, occasional rocks and fences etc protruding into the river.
Grade II	The water is faster and rapids are more frequent: rocks, waves and small stoppers are found. There is an obvious channel, but there may be obstructions.
Grade III	Difficult. The pace quickens with fairly big waves, and stoppers which are capable of holding a boat firmly. Rapids are much more continuous and although the route is fairly obvious, it may be necessary to inspect from the bank, and it is necessary to be able to manoevre the canoe or kayak skilfully.
Grade IV	Very Difficult: long stretches of heavy rapids and falls with irregular waves and often powerful holding stoppers. The route is not obvious from the water, and bank inspection is usually necessary. A mistake or swim could be serious.
Grade V	Extremely Difficult: longer rapids, large drops with very big waves, dangerous stoppers and rocks to negotiate. This is a challenge to any canoeist. Substantial danger is always a possibility. Continual inspection and/or protection is necessary.
Grade VI	The limit of difficulty: there is always a risk to life.