Idaho Paddler's Website: a supplemental resource for users of the book Guide to Idaho Paddling.
Guide to Idaho Paddling about easy rivers, and thus we tried to be as conservative as possible when rating rivers. Rivers are rated on the International Scale of River Difficulty. The scale goes from class I to class VI, where I is easy water and class VI is extremely difficult and dangerous. The rivers covered in this book are mostly class I and II with some class III. The American Whitewater Affiliation defines each of those classes in the following terms:
Class I Fast moving water with riffles and small waves. Few obstructions and easily missed with little training. Risk to swimming is slight; self rescue is easy.
(This is the classification that we feel needs to be expanded. Many rivers in Idaho are commonly classified class I, but no matter how you look at them, they simply don't meet the "little training" or "risk to swimming is slight" tests.)
Class II 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 Rapids with moderate, irregular waves which may be difficult to avoid and which can swamp an open canoe. Complex maneuvers in fast current and good boat control in tight passages or around ledges are often required; large waves or 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.
The Expanded Class I Scale
Class I water? It's easy. Any beginner can run it, right? We say no. As we have spent more and more time on so-called class I water, we have come to learn that it covers a lot of ground. Let's take a look at two stretches of water in Idaho: Big Springs in the Island Park area and the Boise River below the city of Boise. Both are rated class I.
Big Springs flows through open meadows with barely a discernible current. It's definitely easy, one can do it with little training, and it is a good trip for families.
But the Boise River is another story. As the Boise River goes around the south side of the several-mile-long Eagle Island, it is swift and flows through a narrow, twisting river channel with lots of overhanging trees. Eddies are small and hard to catch and you can come around a corner and suddenly be faced with a tree all the way across the river.
Is this stretch of the Boise River easy? No. Can you do this stretch with little training? Once again, the answer is no. In fact, it takes good boating skills and a fair amount of experience. Moreover, we feel that something like the Boise takes more finesse, knowledge and training than many class II rivers. Yet no one would ever rate the Boise River (other than the short rapids created by its diversions) as class II.
If you are a beginner, or if you are going out with your family or friends, the class I rating fails to tell you what you are really getting into.
To help provide a better gauge of the difficulty of this type of water, we use an expanded class I system in this book. Instead of using something completely new which might be confusing, we utilize the international scale but expand it slightly. For those who are comfortable with the international scale, it's there, but those who want a finer way of distinguishing between rivers, it's included as well. For instance, we rate the Boise River around Eagle Island as the following: class I+ (1.5).
Here's a closer look at the expanded class I scale:
Class I (1.0) Flat, lake-like water. No current or very slow moving current. One can easily paddle upstream and downstream. This the safest water for families and children. Since the water is slow moving, downriver trips against strong winds, may be taxing.
This water is suitable for flat water canoes (with V-shaped bottoms) and lake and sea kayaks as well as all other river craft. Inflatable boaters, however, may find this water sluggish, requiring a lot of paddling to get downstream. (Some boaters might call this type of water class I- on the international scale.)
Class I (1.1) Flat water with some current. One can paddle upstream, but it takes more effort. Since it has current, it may have some minor eddies. This is also safe water for family trips. Suitable for flat water canoes, lake kayaks and other river craft. (Easy class I water.)
Class I (1.2) Flat water with current, minor riffles and some eddies. Paddling upstream is possible in some places, but in other places it may be very difficult or not possible at all. These rivers may have some overhanging trees and brush. Unless experienced and competent, families with small children probably should not run them. This water can be run in lake canoes and kayaks, but boats designed for rivers are more suitable. (Moderately easy class I.)
Class I+ (1.3) Moving water with mini-rapids. Small, mini-rapids may occur in swift areas of the river—or where the river slides down gravel bars. The river may have some swift corners with overhanging trees on the outside of bends. Rocks and boulders may be present which need to be avoided, but the current is gentle and not strong enough to cause a boat to get wrapped or broached.
Basic maneuvering skills are needed, including the ability to move to the right or left and avoid the outside of bends, and the ability to miss an occasional rock. Boaters should know the basics of an eddy turn and how to use an eddy to stop, as well as understanding the preliminaries of reading water. River canoes and kayaks are preferable to lake boats. (This is the beginning of class I+ water.)
Class I+ (1.4) Swift water with mini-rapids, small waves and obstructions. The river may bend sharply and the current on the outside of bends is more forceful. Such rivers may have narrow channels with long stretches of overhanging trees and brush in which a boat can get hung up and flipped over.
Canoeists and kayakers should have a good understanding of how to lean boats while in the current, or while turning in and out of eddies, or if accidentally pushed up against an obstruction. Boaters should be very comfortable maneuvering the boat through rocks and have the ability to catch small eddies. A sureness of technique is needed to stop quickly if fences, trees or diversions are encountered.
The best craft are river canoes, kayaks and other river boats. Note that some inflatable kayaks may be too sluggish to handle the type of maneuvering needed for this type of river. (This is difficult class I water, well into the class I+ range.)
Class I+ (1.5) Rapid water with small rapids, waves and obstructions. The river may be very narrow and have many sharp turns and long stretches of overhanging trees and brush. In higher flows, trees, log jams and other strainers are dangerous.
Some waves may be present which, if run sideways, can swamp a canoe. Improper leans in a canoe or kayak can cause a capsize. Boaters must have the ability to read the water, anticipate future moves and react quickly. A well-practiced, reliable eddy turn is a must.