The Changing Rapids of Grand Canyon:
Boucher Rapid

No shit, there we were. The Inner Gorge on 4,000–5,000 cfs in late October 1987. Glenn Rink had a rowing snout; Jon Hirsh was in a Havasu; I was a passenger on probably my fifth Grand Canyon trip. We had blown out the two rear ports in another Havasu on the Mace Rock while running right in Horn Creek. After a night of repeated curses from the boat-repair crew and within sight of Horn Creek's tail waves, we moved downstream towards all those big rapids. And the only one the crew was really worried about was Boucher.
That was the first time Boucher Rapid caught my attention, but it has not been the last. Most guides I know think of Boucher in three terms: first, you don't want to camp there; second, it usually is a wet ride; and finally, that eddy on lower left seems to catch everything floating downstream. What I think about Boucher is its significance in Grand Canyon as an example of a seemingly benign rapid that once was fairly large, and how a rapid can affect another upstream.
Common sense wouldn't cause most guides to point at Boucher as being the site of one of the largest changes in a Grand Canyon rapid (Webb, 1996). After all, the rapid most people see is relatively wide and rocky with few big waves. It wasn't always so. Boucher was consistently rated as a reasonably difficult rapid (six–eight on the Grand Canyon scale; Simmons and Gaskill, 1969) by pre-dam river runners. The drop was thirteen feet in 1923, making it one of the larger drops in the Inner Gorge. When Dock Marston polled pre-dam boatmen about the difficulty of rapids, Boucher scored high on the list.
Boucher Rapid caught someone else's attention in the early 1950s. Bob Rigg was a young man working for his brother Jim at Mexican Hat Expeditions. On their annual summer trip through Grand Canyon, they noticed something different at Boucher, stopped, and found the debris fan to be oozing mud. They also noticed that the rapid, which already was formidable, was narrower with a larger drop. We don't know how much narrower or larger because no one measured it or wrote it down. The memory stuck with Rigg sufficiently that when I asked him 43 years later about the biggest changes he could remember in Grand Canyon, Bob remembered Boucher. He thought the year it changed was either 1951 or 1952 (Melis and others, 1994).
The early 1950s debris flow inundated most of the debris fan, leaving untouched a boulder terrace downstream from the mouth of the canyon. That boulder terrace, indicative of a far-larger debris flow, caused my crew to hike into Boucher Canyon and seek a date for the larger event. We found a tree branch trapped among very large, slightly weathered boulders upstream from the mouth. Radiocarbon dated to between ad 1436 and 1638, this debris flow must have completely changed Boucher. We also noticed that a small debris flow had occurred in 1984, unnoticed by river runners who had high-water boating on their minds. All this led to our conclusion that Boucher Canyon produces frequent debris flows.

The reason Boucher Rapid scares few people anymore is that large, nasty rapid downstream: Crystal. When the 1966 debris flow hit Crystal Rapid, it raised the water surface at the head of the rapid a considerable amount (the drop through Crystal rapid increased from seventeen to 30 feet), creating Lake Crystal. The head of Lake Crystal is the toe of Boucher; in other words, the backup created by Crystal Rapid has drowned out the tail waves of Boucher, reducing its drop and severity. But this has been known for decades (Simmons and Gaskill, 1969).
What isn't known is what Boucher Rapid did to its nearest neighbor upstream: Hermit. Other than a small debris flow in 1996 that, among other things, really strengthened that fifth wave, Hermit hasn't been changed by debris flows from Hermit Creek. We do know that a prehistoric debris flow dammed the river here; the evidence is over there on the right bank. In this sense, Hermit Rapid is in the same class as Lava Falls and Tanner Creek rapids, all with a large, prehistoric debris flow. Hermit is also in the same class as Boucher, because the 1951–1952 debris flow drowned out Hermit's tail waves, making the rapid easier to run, believe it or not.
In our language, we use the metaphor of a pebble thrown into a lake creating ripples that extend radially, affecting a larger area. In Grand Canyon, we should think of debris flows as having ripple effects upstream. So, you might remind people of Lake Boucher as well as Lake Crystal and tell the story of young Bob Rigg and the oozing mud on the debris fan. One more thing: you might have wondered why some large canyons, such as Clear Creek, do not have significant rapids. Look downstream, and you will see Zoroaster Rapid, which drowns out “Clear Creek Rapid.” Trust me, Clear Creek Rapid will rise again. So will Boucher.

Bob WebbMelis, T.S., Webb, R.H., Griffiths, P.G., and Wise, T.J., 1994, Magnitude and Frequency Data for Historic Debris Flows in Grand Canyon National Park and Vicinity, Arizona: U.S. Geological Survey Water Resources Investigations Report 94–4214, 285 p.
Simmons, G.C., and Gaskill, D.L., 1969, River Runners' Guide to the Canyons of the Green and Colorado Rivers, Volume III, Marble Gorge and Grand Canyon: Flagstaff, Northland Press, 132 p.
Webb, R.H., 1996, Grand Canyon, a Century of Change: Tucson, University of Arizona Press, 290 p.