SEVEN

Rating Whitewater and Rivers

Part of preparing for a trip, especially a trip to a new area, involves assessing the challenges en route, then making a realistic appraisal of group skills and abilities. Whitewater is one of the constant themes of a paddling career, whether or not you’re a boater who seeks out the exhilaration of rapids, and much of the discussion before a new trip centers on the level of whitewater challenge along the way.

A good deal of information about the character of a river can be gleaned from a close reading of topographic maps (see this pagethis page). Scrounging up old trip reports or following up word-of-mouth leads is also productive. In any event, once we start discussing the level of whitewater challenge, we need some sort of scale to measure against.

The traditional whitewater rating scale is based on a I to VI classification system, where class I is the easiest and class VI the most difficult. Not just specific rapids, but entire sections of rivers can be described as having a class II or IV character. Descriptions for each category go something like this:

Class I: Easy. River speed less than hard backpaddling speed. Route finding simple. Occasional small rapids, or riffles, with regular low waves. On narrow class I rivers some care may be required to avoid gravel bars, fallen trees, and overhanging brush.

Class II: Moderate. River speed sometimes exceeds hard backpaddling speed. Current generally easy to read. Rapids more frequent but unobstructed, with regular waves and easy eddies. Scouting often not necessary.

Class III: Difficult. River speed often exceeds hard backpaddling speed. Maneuvering in rapids required. Numerous rapids that require scouting, with large standing waves, ledges, strong eddies, and other obstacles. Main river current pushy and challenging.

Class IV: Very difficult. Long, obstructed rapids with unavoidable turbulence, very large and choppy waves, powerful eddies and boils, abrupt river bends and strong crosscurrents. Scouting always necessary and route finding complicated. Difficult and infrequent landings increase the dangers of long and hazardous swims in case of capsize.

Class V: Exceedingly difficult. Wild turbulence. Very powerful and conflicted current. Scouting often problematic. Life-threatening consequences in the event of mishap.

Class VI: Limit of navigability. All whitewater dangers taken to the upper limit. Negotiable only by experts at favorable water levels. Even then, cannot be attempted without risk of life.

This framework for discussing a river’s difficulty, and particularly its whitewater challenges, provides a general foundation. Most conversations about a river go beyond these generalities to cover such things as the changes wrought by different water levels and the specific character of whitewater.

Class III rapids can be “big wave rapids” or “technical rock gardens.” A river may be class II overall, with one class IV ledge drop that is an obvious portage at most water levels. Other rivers will have discrete sections of very different character. The Green River in Wyoming and Utah, for instance, has big rapid runs through Split Mountain and parts of Gray’s and Desolation Canyons, but it’s quite benign and placid through Stillwater and Labyrinth Canyons. Rivers may also alternate between flatwater stretches and canyon sections with more difficult water. The Rio Grande in Big Bend National Park, Texas, is a good example—meandering current across open country interrupted by sheer-walled limestone canyons with some formidable water. Finally, when you travel a long section, or the entire length, of a river, there’s almost always one particular stretch that is most notable for turbulence, where gradient or topography conspires to create the most significant whitewater.

In the world of serious whitewater boating, the old classifications have become outmoded and inadequate. In terms of canoe tripping and general discussion, the old I to VI guidelines are still workable, but in the realm of cutting-edge paddling, the old guidelines cried out for revision.

American Whitewater (AW) has developed a new set of whitewater rating guidelines devoted to addressing problems with the old system, and they are useful additions for all paddlers. The former categories are too general, for starters. Class IV rapids can run the gamut from rollicking rides down a big wave train to really gnarly runs through boulder fields that require repeated and very difficult maneuvers. Also, whitewater boating has evolved to the point that the skills of paddlers and evolution of equipment have rendered rapids previously thought unrunnable accessible to a significant number of boaters.

The new system retains the I to VI categories but adds pluses and minuses to levels I to IV Class V has been radically altered, much like the revised rating system for rock climbing that came into use years ago, when the limits of that sport were being pushed. Class V now begins with 5.1, goes to 5.2, and so on, without an upper limit. Each point jump is equivalent to a leap in class. In other words, going from 5.3 to 5.4 is similar to moving from class II to class III.

Class VI has been turned into an exploratory category until a rapid can be placed in the new class V hierarchy. There is no established cubbyhole for unrunnable water, largely because so much water once deemed unnavigable is now run routinely. Each rapid is assessed from the perspective of how it feels to a boater making a first run down it. Furthermore, the ratings are pegged to specific water flows.

More than a hundred well-known rapids have been used to set “benchmarks” for categories of difficulty. For example, Diamond Splitter Rapid on the Ocoee River, at 1,200 to 1,600 cubic feet per second (cfs), is a standard class III. Hermit Rapid in the Grand Canyon, when the Colorado River is flowing at 15,000 to 22,000 cfs, is the epitome of a class IV.

Of course all this is just the corral we construct to contain the discussion of whitewater. There’s still lots of wiggle room. Consider water flow, the ability to sneak along the edge of a rapid, the particular challenges of turbulence and how they match against a boater’s skills and the design of the canoe. How remote the river is, whether the boat is full or empty, whether it’s a sunny, warm day or a sleety, gray day. Whether there’s a nice pool at the bottom of the rapid where you can collect yourself (and possibly your gear). How skilled, fatigued, appropriately dressed, and mentally prepared other members of the group are at a particular moment.

In the end, these may be the more important calculations that each boater looking at every new rapid has to reckon with before coming to a sensible decision.