October 2, 2012
The Mississippi is like a giant beast that the Army Corps of Engineers has engaged in a continuing battle of submission since the 1830s.
The river has never wanted to stay in place. It wants to wander and curve, braid out and come together, break through bends, flow down chutes, flood and recede, meander. As long as people have settled on its banks, the river has refused man’s invitation to be civilized.
It cuts through curves and leaves river towns stranded far in the country. It makes islands disappear and reappear miles downstream. Its snags, reefs, and shifting rocks kept the average lifespan of a paddle-wheel steamboat to low single digits, but all that’s bad for business.
The Corps went to work. Boats pulled up thousands of snags and deadheads. They dredged out sandbars until they were nice and deep and dug canals around rapids. If a rock stuck its head too high, the Corps blew it to pieces with a stick of dynamite.
When congress wanted a six-foot channel on the upper Mississippi, the Corps threw heaps of rock and brush in long lines that extended hundreds of feet offshore. These “wing dams” pushed the current toward the main channel, cut off backwaters, and shoved the river into place.
Islands began to sit still, curves didn’t shift, decades of effort beat the river into a bit of submission.
Then, in 1930, the Corps began work on the Lock and Dam system to create a nine-foot channel from St. Louis to Minneapolis and bring bulk freight to the Midwest.
The dams flooded the Mississippi Valley, turning the river into a series of deep and steady pools. With each dam, the Corps built a lock to connect the pools on either side by raising or lowering a piece of river like a giant water elevator big enough for nine barges at a time.
There are 29 locks on the upper Mississippi. The first two are Upper and Lower St. Anthony Falls. The next 27 just go by a number, with a few quirks. Number 23 never made it beyond the planning stages because Number 24 is an overachiever. The same can’t be said of number 6. It would have flooded Winona, Minnesota, so they added 5A and now 6 only drops a meager 5 feet, not much compared to the 49 foot drop at Upper St. Anthony’s.
Locks work by raising and lowering the water between two giant doors. To go down, the operator floods the lock to match the river above the dam and opens the top door. Once inside, the door shuts and valves drain the water away until it matches the river below the dam. When the lower door opens a new pool awaits, calm and at least nine feet deep.
Nine barges can fit inside a lock with two and a half feet to spare on each side. A single towboat can lock through twice, so the biggest barge floats you’ll see above St. Louis are seventeen barges tied together three barges wide and six deep, with the tugboat pushing at the rear between the last two barges.
So that’s where the war stands between the river and the Corps. It almost feels over, like the Corps has won and the river is content to be tame and paraded out as an artery of commerce.
But I look at the banks and see houses built high on stilts. I hear about low water stopping traffic near St. Louis and dredges working overtime as barges wait in lines miles long. I see patches and cracks in the concrete walls of the locks.
No, the river will never give up, never stop testing its chains, chipping away its cage, because it was wild once and it will never forget the taste.