Part 4: The locks
The Mississippi River drops 420 feet in the 699 miles from Minneapolis to the mouth of the Ohio River. In the past, it made those drops through waterfalls and rapids, but now, 29 locks and dams have turned the river into that many placid lakes for towboats and barges to ride up and down, taking grain south and fertilizer north.
Lock and Dam No. 9, a few miles south of Lynxville, Wisc., was built in 1938 and cost $4.7 million. It runs about two miles across the river from Iowa to Wisconsin, beneath the woodsy bluffs that mark the course of the river.
The Sierra Dawn is churning upstream along the 9-foot deep channel cut close to the Wisconsin shore. Further west, the river cuts through a maze of channels and islands that create an unnavigable morass of sloughs and shallows.
The Sierra Dawn is one of those four-story high, white painted vessels known as towboats, although the name is clearly a misnomer: It pushes rather than pulls. Imagine, instead of towing a boat-trailer behind your Suburban, you tied 15 trailers together and pushed them up the highway. That is what these towboats do.
And the Sierra Dawn is pushing the full complement of 15, tied together in five ranks each three barges wide. Each barge is nearly 200 feet long, followed by the towboat that is another 150 feet.
With five ranks of barges and the towboat, the whole assembly stretches up the river for a quarter of a mile, aimed rather than steered up against the current.
The size is immense. Each barge weighs 15,000 tons and altogether, the raft of them weighs in at 22,500 tons and carries 6.8 million gallons of cargo. Each barge holds the equivalent of 15 railway cars and one tow unit equals more than two full-length freight trains.
It approaches the lock, which is only 600 feet long, a thin channel only feet wide, a well-worn and scraped concrete canyon right beside the shoreline.
The barge-and-boat freight train slows and inches into the slot of the lock, with its deckhands speaking to the pilot in the towboat’s wheelhouse via walkie-talkie. It slows to a near halt just before bumping the north end of the slot and a lockworker tosses a small line to the bargehand, who attaches it to a hawser and has it hauled up and hitched to a kevel — one of those anvil-shaped cleats — on the lockside.
It grinds and moans as the rope stretches and tightens around the metal. It sounds like the groaning of a horror-movie door, although with the sound-volume of a chain saw.
Obviously, the boat assembly is too long for the lock, so the first nine barges are separated from following six and the towboat, which inch back out of the lock.
This is a slow and tedious process. Those of us in the lookout tower watching the event have plenty of time to take in the other happenings on the river.
Out toward the middle of the stream, a flock of 50 or more ducks sits in a crowd, floating on the water, pulled slowly by the current downstream. The flock drifts dangerously close to the spillway of the dam, where the current speeds up and drops over the edge into the rapids just below the dam.
But just as the ducks look like they are goners, the few closest to the havoc skitter forward into the middle of the flock and settle down once more, floating backwards again.
Over and over the nearest three or five birds splash their way up in the flock, spinning a rooster-tail of water behind them as their feet catch in the water.
During this little comedy, the locks close on the nine separated barges and the water level rises to match the upstream level.
The upstream gates then swing open and spectators wonder: How will they move the barges without a towboat attached?
Well, a lock worker drags a heavy steel cable back with a Cushman vehicle — like a golf cart — along the top of the lock to a point about halfway down the bargeline, and with a talent worthy of a Will Rogers, swings it over the side and loops it around a kevel on the gunwale of the barge, yanking it shut like a rodeo cowboy roping a steer. A winch at the far end of the lock begins moving the barges out of the slot.
As the last barge passes under us, I can see one deckhand, dressed in overalls and a bright orange flotation device, sitting on the deck at the back of the barge, his legs stretched straight out. He is relaxing, smoking a cigarette.
“Where’s these barges from?” I yell down to him.
“St. Louis, I guess. I got on at Rock Island.”
The morning had been foggy on the river. I asked him about that.
“Yep, we had to tie up about two last night and didn’t start again till nearly noon.”
He floated right on past us.
Normally, towboat crews work smaller sections of the river, and sign up for a 30-day-on and 30-day-off schedule.
“What’s in the barges?”
So far, this has all taken a little over an hour. It is excruciatingly slow.
When the loose barges are tied up north of the lock, the gates close upstream, the water level lowers once more and the downstream gate opens for the second half of the train.
It churns into the lock a slowly as glacier. There is not two-feet of leeway on either side.
The flat fore-end of the lashed barges creates a series of artificially straight bow waves that move up the slot of the lock like the waves from a wave generator in a demonstration box.
And not seven feet in front of the tons of rusty creaking steel swim two tiny mallards, as though oblivious of the doom crashing down on them. They swim, waggle their tails, plunk their heads under the surface and shake their beaks free of water, always just that little step ahead of the barges. It almost looks as if the ducks are towing them.
The gates close, the water rises, the gates open and the front and back halves of the barge assembly are once again rejoined. The whole process takes over two hours. Another raft of barges heading south is waiting for the lock to clear so it can have its turn.
Lock No. 9 goes through this process about 6,000 times a year. And there are 28 other locks along the stretch of river between St. Anthony Falls in Minneapolis and the mouth of the Ohio River at Cairo, Ill.
Below that, the river flattens out and flows naturally.
As the towboat chugs its way out of the lock, a half-dozen seagulls swoop in behind it to see what might be edible in the churn of the wake.
To be continued