Engineering for man: Shaping the Mississippi River
Sunday, April 27, 2008
In his nostalgic look back at his career as a steamboat pilot in "Life on the Mississippi," Mark Twain described the difficult task of navigating the river in the pre-Civil War era.
"Piloting becomes another matter when you apply it to vast streams like the Mississippi and the Missouri, whose alluvial banks cave and change constantly, whose snags are always hunting up new quarters, whose sandbars are never at rest, whose channels are forever dodging and shirking, and whose obstructions must be confronted in all nights and in all weathers without the aid of a single lighthouse or a single buoy for there is neither light nor buoy to be found anywhere in all this three or four thousand miles of villainous river."
The river described in that passage no longer exists. Even before Twain became a pilot in the 1850s, Congress directed the U.S. Army Corps of Engineers to make navigation safer. In the Roads and Canals Act of 1824, Congress appropriated $75,000 to support the removal of snags, sandbars and other obstacles to navigation. "You could safely say that Mark Twain's checklist is the one used by the corps over the years to make navigation safer," said Jim Pogue, spokesman for the corps' Memphis District office.
But while good for man and his economic interests, the alterations have devastated nature, environmental groups argue. "U.S. Army Corps of Engineers projects and project operations are among the leading reasons North America's freshwater species are disappearing as fast as tropical rainforest species and five times faster than land-based species," begins an Environmental Defense Fund report dated May 2002.
The corps is willing to admit that for most of its history, nature was a force to be mastered and not a factor in the value of its projects. But in recent decades, the environment has become increasingly important, Pogue said. "You could say it is like a bucket of liquid that has been poured over everything, that permeates everything we do now," he said. "Everything we construct first of all has environmental considerations and, whenever possible, has features included that improve the environmental impact of what we are doing."
A river that stays put
The Mississippi River is the nation's largest ongoing engineering project. The river remained little changed from the time the Jesuit priest Jacques Marquette canoed from the mouth of the Wisconsin River to the mouth of the Arkansas River in 1673 until Twain's boyhood. But from 1837, when a lieutenant from Virginia, Robert E. Lee, designed revetments and dikes to force the river to scour the St. Louis harbor, to today, the Mississippi has been transformed.
Dikes, bank revetments, weirs, levees, dredging and even explosive removal of rocks have all been used to lock the river into place. No longer does the river, as Twain wrote, have a "disposition to make prodigious jumps by cutting through narrow necks of land and thus straightening and shortening itself. More than once it has shortened itself 30 miles at a single jump. The Mississippi does not alter its locality by cut-offs alone. It is always changing its habitat bodily — is always moving bodily sidewise."
Today the Mississippi is a stream that stays put, self-maintains at low water most of its own 9-foot-deep shipping channel and which, at most high-water stages, stays off land transformed by the vast engineering effort from swamps subject to almost annual flooding into some of the most productive farms in the world.
The corps has learned to direct the river without attempting to overcome its natural force, said Claude Strausser, a retired corps engineer.
"We make suggestions and ask the river to pay attention," Strausser said. "As Col. J.H. Simpson said, a mighty river is impatient under restraint. It can be led, but not driven." Simpson was the first commander of the corps' St. Louis District.
That 1837 project, designed by Lee using surveys and drawings, achieved its goal. In the modern era, the corps uses hydrologic response models at the Applied River Engineering Center in St. Louis to test alternatives for new river structures.
The engineering has moved into the realm of environmental restoration and mitigation, but only within the constraints of the corps' other duties, Strausser said. Changes suggested must maintain the river channel.
Examples of engineering projects that have added habitat include chevron dikes, the first of which were placed near St. Louis and have resulted in the establishment of new islands. Others closer to this area include the Santa Fe Chute and the Sister Chute below Cape Girardeau, which have helped build a large island visible from the downtown riverfront.
The engineering center has models of the river near Cape Girardeau, and the corps is working out how to improve the shipping channel near the Red Star river access boat ramp in a way that scours away the sandbar that collects at the base of the ramp in low water. The removal of the sand is not an official goal of the corps, but it wants to design any new structures in a way that solves the silting while potentially building an island just upstream or adjacent to the boat ramp.
The corps' environmental programs are gaining praise from many environmental groups. Strausser worked throughout his career to quiet criticism by organizing annual River Resources Action Team river trips, bringing resource agencies, environmental groups and other river interests together. And even the groups most at odds with the corps have muted some of their criticisms. "The corps is trying to make some changes to better manage wildlife, to be more environmentally sensitive," said David Conrad, senior water resources specialist with the National Wildlife Federation. "But there are still a myriad of examples where the engineering for almost exclusively human ends continues to dominate. We still see a lot of situations on the Mississippi River where there is outright resistance to making environmental improvements that make sense all around."
Flood Control Act of 1928
May 15 will mark the 80th anniversary of the most ambitious program to control the river, the Flood Control Act of 1928.
Written in response to devastating floods in 1927, the act authorized $325 million for a "project for the flood control of the Mississippi River and its alluvial valley and for its improvement from the Head of Passes to Cape Girardeau, Missouri."
That $325 million was a down payment on the cost. According to the script of a weekly radio address by U.S. Rep. Jo Ann Emerson, R-Cape Girardeau, $12.9 billion has been spent over 80 years on flood protection under the act. That investment, she said, has prevented $306 billion in flood damages.
The downtown floodwall in Cape Girardeau is part of that project. Completed in 1964 at an inflation-adjusted cost of $36 million, the wall protects against a river reaching 54 feet on the local river gauge, almost 6 feet higher than the record level of 1993. By corps scorecards, the wall has prevented $170.5 million in flood damage.
That flood protection has been needed repeatedly this year. The river, after two years of drought, has crested above the 32-foot flood stage four times, the highest at 41 feet, with another crest of 36 feet predicted to arrive Wednesday. The river has been above flood stage continuously since March 19 except for a brief 20-hour period.
The Flood Control Act of 1928 implemented the Jadwin Plan, named after Maj. Gen. Edgar Jadwin, the Chief of Engineers. It is 94 precent complete, Pogue said, with the biggest remaining piece being the controversial plan to build a levee across a 1,200-foot gap at New Madrid known as the St. John's Bayou & New Madrid Floodway project.
Authorized in 1954, construction on the $112-million project was halted in 2007 after about a year of work when a federal court, responding to a lawsuit brought by a group of environmental organizations, ordered the corps to stop and remove what had been built.
The plan for the New Madrid floodway closure included $34 million to purchase land for mitigating the environmental damage, most of it to be planted as bottomland hardwood forests, said Dennis Ward, fish and wildlife biologist with the corps' Memphis District.
But Conrad, of the National Wildlife Federation, said claims for damages prevented are "illusory" and that the mitigation plan for the St. John's Bayou project won't undo environmental damage. Levees, he said, offer an illusion of safety. "There is no levee that is fail-safe," he said. "The failure to recognize that is showing itself [in] increasing catastrophic flooding."
Moving people out of the way of floods, not piling up dirt and rock, is the most sensible plan, Conrad said.
The Missouri River and Tributaries Program, as the Jadwin Plan is officially known, is designed to defend against the maximum probable flood.
But solid data collected about the river is all relatively recent, and experts don't have enough information to determine what that maximum flood level would be, Strausser said. There are estimates, poorly done in Strausser's view, of the size of historic floods. But good data is available only since the 1930s. One of the best examples of the efficacy of flood protection came in 2002, he said. In 1903, a flood filled the valley from the bluffs in Illinois to the St. Louis riverfront. A flood of similar size took place in 2002 but did little harm.
The goal is damage reduction. A levee doesn't fail if the water goes over the top, he said. And moving people, while achievable in some locations, isn't feasible everywhere, he said. "Society has decided they want to be protected from that event," he said. "The question is, do you want to live behind a flood protection system or do you want to run to the hills every time the river goes up? What are you trying to achieve?"
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