Reading River Conditions

Stream of the Little Bull Trout is what the Salish people called it.^[1]Salish-Pend d’Oreille Culture Committee and Elders Cultural Advisory Council Confederated Salish and Kootenai Tribes, The Salish People and the Lewis and Clark Expedition, (Lincoln, University … Continue reading When Meriwether Lewis crossed it near its confluence with the Clark Fork River on the 4 July 1806, he noted it merely as “a stream about 15 yards wide.”

I took this photo a mile up the canyon. As it shows, the Rattlesnake is a very swift, small stream. You can see that only 300 cfs over a rocky bed can make a very strong water. It drops about 80 feet per mile (10 feet/mile produces fast water), and in the picture was running at perhaps 10 miles an hour. I have canoed it in high water, but that’s dangerous. Just one new downed tree since your last scouting could spell the end of your canoe, at the very least.

The Blackfoot River here is about 50 yards wide, and is running at 5,000 cfs. The main current, as usual, is towards the outside of the bend, here on the far side of the river. The slack water in the foreground, a good place to land, is caused by the trees and a small sand and vegetation bar (“point”) above it; in bigger water, as we shall see, that slack feature might become a big eddy with a vicious eddy line.

You can see a big difference between the wide, slow section above, and the rapid section below. The two sections of river are only a few hundred yards apart, yet are flowing at the same cfs. As the pictures below demonstrate, the same cfs can form very different rivers or sections of river, depending on gradient (the drop per mile), the stream width, and the bottom: smooth, small rocks, huge rocks, etc. Rivers having long smooth sections followed by sudden “ledge” drops are called “pool and drop” rivers. The Grand Canyon is a dramatic example: the pools may be nearly still for a mile, followed by a severe drop with a funnel entrance and huge waves. The Missouri in the Breaks is a mild pool and rapids river; the “pools” have a decent current, and only a few rapids, like Bird Rapid, might be considered drops—”a sudden decent,” as Lewis said.

Descending the river, from upper right to lower left, the steersman faces two decisions in a few yards, at points A and B in the photo: First (A), should he take the smaller right channel, or the left channel with more water but a big rock. Second (B), should he go right or left of the rock. Right and left here mean “river right “and “river left,” as seen looking downstream. The custom is very useful when on the bank, scouting and pointing up and down the river. “Let’s go left of that rock.” “River left?” “Yeah.”

What should the steersman do here? The river left channel (foreground) has more water, so in the absence of visible features ruling out one channel or the other, he would choose the larger channel, which is the main current. Then, right away he faces the second choice: right or left of that submerged rock, which creates a white “pore over” hole that might “keep” a canoe, or turn it sideways and flip it. The choices here are easy and obvious—left, left—and were probably made upstream of the picture, behind the bushes upper right. Even on an easy river, and especially in canoes loaded with over two thousand pounds, the steersman must be alert and looking 100 to 200 yards downstream.

Lining upstream, the choices would be the opposite. The “river right” channel on the far side has shallower water and might be walkable. Much of the Jefferson River, as they ascended with full canoe loads and great effort, would have been about the size of the Blackfoot, 5,000 cfs.

The size of the Blackfoot above is also similar to that of the Clearwater River in Idaho, which the expedition descended in the fall of 1805 from their Canoe Camp at Kamiah to the Clearwater’s entrance into the Snake River at today’s Lewistown, Idaho. (See Clearwater Canoe Camp, Potlatch River, and Snake River.)

The Clark Fork River (Clark’s Fork of the Columbia, to be exact), is pictured here above Missoula, after the Blackfoot has joined it. Lewis and his contingent walked past this point early on the 4 July 1806, but aside from getting dunked when swept off the makeshift raft his men made to ferry him across the Clark’s Fork several miles downstream, neither he nor any of the rest of the Corps ever canoed on it. At this point it is a fast but calm, fairly big river of 10,000 cfs, 90 yards wide.

On the Blackfoot you would be dodging rocks. By comparison, this is an easy float down. However, the river here would be harder than the Blackfoot when lining upstream, with overhanging vegetation and deep water along the left bank in the picture (river right). A great deal of the upper Missouri above the Marias might have been in this 10-20,000 cfs range, especially above the Gates of the Mountains. In 1889, G. C. Broadhead cited an estimate that the Upper Missouri just below the Three Forks was running at 8,521 cfs in late May.^[2]The upper Missouri above the Marias and the Dearborn and the Gates of the Mountains was about a 10,000 cfs river, before dams. The upper Missouri’s bed and gradient, between rapids, is similar … Continue reading

Below town, the Clark Fork has been doubled by the Bitterroot River, and is 20,000 cfs and 170 yards wide. At this size, the river has considerable hydraulics: the churning of the water as it moves, although without obstacles, so that even in smooth water such as this your canoe may be turned this way or that, or pushed sideways a few yards. This is a characteristic of high water; the river is not comfortable in its bed. In the picture above, the “bay” on the right is a large eddy which sweeps around and upstream to the “point” of land upper right. Note the limb sticking up, part of a submerged tree stuck in the sand of the eddy. It reappears at the far left of the picture below (Fig. 23-b).

The eddy is flowing swiftly upstream; note the slight wake behind the tree limb at the left of the picture. When the eddy (B), at its top, meets the main current (A), it folds underneath. Within the brackets is a strong eddy seam or “line” about 4 to 15 feet wide, stretching 30 yards downstream, along which the two currents slide by each other in opposite directions, creating turbulence and small whirlpools. A 33′ canoe paddled across that line would have its bow in one current and its stern in another current going in the opposite direction. The boat whips around, and the crew must be ready with bracing strokes and draws to keep it from turning over. An eddy is a good place to land, but getting in and out of it can be tricky. You usually land at the bottom of the eddy, but to exit, you often have to “crash” the upstream eddy line. There is no doubt that the Lewis and Clark expedition had to perform these difficult maneuvers thousands of times. Even when ascending, they often crossed the river for better lining, and would have left from an eddy on one shore, to enter another on the opposite shore.

Lining, the crew would be pulling the canoe or pirogue upstream, but in the eddy current, which itself flows upstream, they would probably be holding the boat back with a stern rope, until they reach the point of land visible upper right in picture A. Many passages in the journals discuss crossing the river to use eddies as they ascend, and the difficulty of rounding the points of land at the top of eddies, where the boats (double manned, as Lewis says), have be dragged upstream against the full force of the current.

Looking downstream past the Cliff Swallows feasting on an emerging hatch, we see small waves and mild hydraulics –”boils” of swirling water—even in this slow stretch of river. There is slack water or an eddy behind each the point on the inside of the bend river right. The Clark Fork here, about 300 yards wide, is probably quite similar—in volume, gradient, and bottom—to the Missouri River in the Breaks in 1805, in between rapids. If lining upstream, Lewis and Clark would have chosen the bank on the right in the picture, pulling up and around the points to the next eddy.

Not far around the bend in the distance, however, a rapid at 40,000 cfs shows us what Clark observed in the lower Columbia: “strong” water, with “whorls” and “suck.”

The Clark Fork here, at 40,000 cfs, with constriction and a decent drop, and about 200 yards wide, may give some idea of Bird Rapid in the Missouri Breaks in 1805. The rapid is “bank to bank”, as Clark said of Bird rapid, and difficult indeed. You see 3′ waves, swirls and mild whirlpools. There is no easy “sneak” on the sides to avoid the wave train.

Lining upstream would not be easy. On the far bank, waves reach almost to the shore. In the foreground, where they would have lined, there is no real eddy, just turbulence flushing through. It would be hard enough to pull a 33′ dugout loaded with 3,000 pounds of gear up the near side past the black rock; then they would have to double-man it through very fast, “strong” water.

Canoeing down a rapid of this volume in high water, the turbulence at the bottom of the waves is often as dangerous as the rapid itself. This whirlpool is only thirty yards downstream of the location in Fig. 24-b, in the tail end of the rapids, and as I watched, it was constantly forming and dissipating, and migrating ten feet upstream and down. In high water, most constriction rapids “pulse,” surging and relenting, always changing. Descending, your choice of route will often give way to improvisation. The water on both sides of the river feeds into the turbulence (on the far side the water is “shelving off” a sloping bottom), making this whirlpool almost impossible to avoid.

Five months after ascending Bird Rapids, the expedition would be canoeing down rapids in the Clearwater and Snake Rivers, rapids much longer than this one, with tricky rock gardens and no safe way to line down. See Appendix.

The Missouri River in the Breaks is a big, strong river. It’s not really “big water;” we usually save that term for over 100,000 cfs, as in the Mississippi, which the Missouri will join in 2,000 miles, making the third longest river system in the world (after the Nile and the Amazon). However, 40,000 cfs is a lot of water in a 200 yard wide streambed with “a perceptible fall.” I am confident that they faced at least class II-III rapids, boils and swirls, debris, and very, very strong, “rappid” water.