Introduction ---
For 170 years the U.S. Army Corps of Engineers have been "nation builders" as well as nation defenders. A major part of this mission has been developing and managing water resources in the public interest. Indeed the hydrologic landscape of the United States has been transformed by locks, dams, reservoirs, canals, levees, dikes, and other features of the Corps rivers and harbors mission. The joint headquarters of the Mississippi River Commission and Mississippi Valley Division commands one of eleven Corps civil works divisions that are organized on the basis of major watersheds. The main concern of the MRC is the 35,000-square-mile alluvial valley that was once subject to periodic flooding. The focus of our work is the contumacious and powerful Mississippi River. Its grandeur and caprice was lucidly captured by Mark Twain, and images of steamboats and the lively commerce and culture they symbolized are deeply embedded in our national consciousness.
To river engineers and valley residents, the Mississippi is metaphorically speaking both a beast and benefactor. This Janus-faced colossus periodically seeks to challenge the flood control system imposed upon it. While its opposite profile is a vital waterway network that extends into the heart of the nation -- a true cornerstone of our economy. Yet the river exhibits a split personality. It is both the author of great floods that once devastated the valley and the purveyor of low water that can clog the channel with sandbars and bring navigation to a standstill. Our mission mirrors the river's schizoid extremes -- protecting lives and property from the ravages of floods and keeping it open for navigation even in severe drought conditions.
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The Basin --
The Mississippi derives its great size and erratic personality from the nation's topography. Whereas Europe may be likened to an inverted saucer with rivers flowing outward to its edge, the Mississippi River Basin is shaped like a huge funnel that drains the nation's interior. From its source at tiny Lake Itasca in northwest Minnesota, it flows southward for more than 2,300 miles to the Gulf of Mexico. Gathering along its way runoff from 41 percent of the continental United States. Its stages and discharges are a reflection of rainfall that occurs over a broad area extending from Idaho to New York. At Cairo, Illinois, where the Lower Mississippi begins, stage differentials of as much as 50 feet have taken place between record high- and low-water seasons.
Managing this great river is difficult due to the alluvial (soily) nature of the valley. In its natural condition the river meandered back and forth with few bluffs or other features to constrict its course. This process is much like turning a water hose loose in a child's sandbox. Consequently, the MRC has developed open river improvements that attempt to confine, train, and stabilize the Mississippi's channels and banks. Its floodplain has also been constricted by levees and floodwalls so that the valley may be safely inhabited.
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Origins of Civil Work---
Looking back we see that the story of managing the "Mighty Mississippi" is a complex, captivating tale. In 1824, the Corps became involved in water resources basically because West Point was the only source of trained engineers in the nation. The small cadre of Army engineers were asked to survey rivers, roads, and canals and remove "snags" from the Mississippi and Ohio rivers to open the waterways for steamboats. Unfortunately, contending political viewpoints over the propriety of federally funded public works resulted in inconsistent funding that precluded efficient and consistent river management before the Civil War.
In 1861, two West Point graduates, Captain Andrew A. Humphreys and Lieutenant Henry Abbot published their great study of the Mississippi -- Physics and Hydraulics of the Mississippi River. Their report was a scientific tour de force, which aggregated a host of data and stated that "levees only" was the solution to valley flooding and suggested other approaches were not feasible. For the Corps, the Humphreys and Abbot report remained the "Bible" of Mississippi River improvements for six decades, but subsequent events would reveal its shortcomings. In the 1870s, one of the greatest navigation achievements was opening the mouth of the Mississippi to ocean-going vessels which had frequently been impeded by sandbars.
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The Mississippi River Commission---
By 1879, the need for improvement of the Mississippi River and coordinating engineering operations through a centralized organization was widely recognized. So in 1879, Congress established the Mississippi River Commission (MRC) and charged it with creating a comprehensive plan to facilitate navigation and prevent destructive floods.
Then, as now, the seven-member commission consisted of three Corps officers, including the president; one member from the Coast and Geodetic Survey; and three civilians, two of whom had to be civil engineers. This composition reflected congressional concern that the MRC exhibit a balance of both Army and civilian engineer expertise.
The daunting task of the MRC required its engineers to study, test, adopt, and discard river engineering techniques employed in Europe and elsewhere. Great mattresses woven from willows were employed to armor the banks -- an approach borrowed from the Dutch. Using concrete blocks for revetment evolved from techniques first developed in Japan. Yet, flood control work was not authorized since many congressmen viewed levees as a local responsibility. The MRC was only allowed to close crevasses in the interest of navigation.
After great back-to-back floods in 1912 and 1913, which produced many deaths and left hundreds homeless, the Congress at last authorized flood control and hundreds of miles of levees were raised and strengthened. And, by the mid-1920s, the MRC became somewhat complacent and alleged the mighty giant . . . the Mississippi, had been shackled.
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1927 Flood---
But in 1927, the river unleashed a holocaust. The valley was ravaged by a brown tide of devastation that inundated 26,000-square miles and drove a half million people from their homes. Clearly, the "levees only" approach of Humphreys and Abbot was bankrupt, and in 1928, Congress directed the Corps to develop a flood control system which would prevent such massive flooding from ever occurring in the future. More than 300 competing flood control plans were put forth. Congress at last adopted the proposal of MG Edgar Jadwin, the Chief of Engineers. The Jadwin Plan had two principal innovations: floodways to divert peak flows and hold down stages in the main channel; and designing all works on a "project flood" -- a great hypothetical flood derived from examining historic rainfall and runoff patterns.
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Mississippi River & Tributaries Project---
The Jadwin Plan and its comprehensive approach to the river's management resulted in the Mississippi River and Tributaries (MR&T) Project authorized by the 1928 Flood Control Act. The MR&T includes several basic elements:
- Levees and floodwalls to contain flood flows, and the main stem system extending from Cape Girardeau, Missouri, nearly to the Gulf of Mexico. The protection is continuous except where major tributaries enter the Mississippi or where natural high ground makes them unnecessary.
- The current construction program consists of raising and strengthening and in some cases extending the existing levees as well as building berms and other features. The system is vast. Some 3,714 miles of levees have been authorized for the MR&T -- 3,410 miles are in place and 2,786 are in place to grade and section. On the main stem of the Mississippi River, 1,602 miles of levees are in place.
- Work on the main stem levees is approximately 89 percent complete. The tributary levees are approximately 75 percent complete.
- The MR&T also incorporates four floodways that divert excess flows past critical reaches so the levee system will not be unduly stressed. The Bonnet Carre' spillway pictured here diverts Mississippi River water into Lake Pontchartrain to keep stages down in the vicinity of New Orleans.
- The channel improvement feature of the MR&T project consists of stabilizing the river banks of the Mississippi to a desirable alignment and obtaining efficient flow characteristics from the standpoints of flood control and navigation.
- Dikes confine the river to a single low-water channel, reduce excessive widths, and develop desired alignments in the interest of navigation.
- Revetment, consisting of huge sections of concrete blocks joined together with wires, help fix the channel and protect nearby levees by preventing bank caving.
- Improvement dredging is employed to adjust river flow patterns and maintenance dredging deepens shallow channel crossings that tend to form during low water.
- Foreshore protection is used primarily in the lower part of the river to laterally protect the river banks from wave wash attack and other erosion.
This encompassing channel improvement feature is approximately 85 percent complete and the scheduled completion date is March of 2010. 1,085 miles of revetment have been authorized and 1,000 are completed. The respective figures for dikes are 339 miles and 265 miles; for foreshore protection 160 miles and 129 miles. Cutoffs were also conducted in the 1930s and 1940s that shortened the river by some 150 miles and reduced flood stages. And in the tributaries dams, reservoirs, control structures, canals, and pumping plants provide for flood control and drainage. We are still working on the MR&T and its about 85 percent complete. As you can see, the nation has derived great benefits from this enormous undertaking.
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Old River---
Since World War II, one of the Corps greatest challenges has been building the Old River Control Structures to regulate the diversion of Mississippi River flows into the Atchafalaya Basin. Over time, the smaller stream was diverting an ever-increasing share of the Mississippi's flow. The initial Old River Structures were completed in 1963.
The Auxiliary Structure was added in 1986 to provide greater control and flexibility of operations. A low-head hydropower facility was completed by non-federal interests slightly upstream of the Corps Old River Structure.
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Navigation---
Of course, keeping the navigation channel open is a major responsibility. The Mississippi is the key element of a vast inland navigation system of over 25,000 miles. North of St. Louis is a system of locks and dams. Below St. Louis the river is free-flowing and a nine-foot channel is maintained. South of Baton Rouge the river is deep enough to accommodate ocean-going vessels. We are also building a lock and dam system on the Red River in Louisiana.
Another major effort is the Melvin Price Locks and Dam on the Mississippi River slightly north of St. Louis.
The first lock chamber has been in operation for several years now and the second was just recently completed & dedicated. The entire navigation system works well, and even provided reliable transportation during the 1988 drought when the river experienced near base-flow conditions.
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Engineering---
The Corps remains on the leading edge in finding, developing, testing, and employing state-of-the-art techniques and practices. Our command remains on the frontiers of river engineering with innovations such as bendway weirs -- low-cost submerged rock dikes, angled upstream, which testing has shown improves bendway channels for navigation. The Old River Auxiliary Structure required putting in place tainter gates that were taller and more heavily loaded than any ever constructed by the Corps. Mississippi River stage data once collected manually is now gathered in real time from 300 stations and instantly transmitted via satellite links. We are also making good use of the Global Positioning (satellite) System to enhance our deep-channel dredging and mat sinking operations.
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The Environment---
During the past two decades environmental considerations have become a major part of our mission. Corps projects and programs now reflect a broader range of considerations such as endangered species, wildlife habitat, and wetlands.
For example, the means are being sought to mitigate the loss of wetlands in southern Louisiana. The state encompasses 40 percent of the coastal marshes in the continental U.S., but experiences 80 percent of the loss.
Many studies are underway and the Corps is developing freshwater diversion structures to place freshwater from the Mississippi River into adjacent estuarine areas to combat saltwater intrusion.
Numerous environmental initiatives are underway in the Yazoo Basin in Mississippi, including
- Extensive reforestation activities that encompasses some 30,000 acres.
- Careful management of water control structures that foster both flood control and environmental benefits by creating 3,800 acres of habitat for waterfowl from November to February.
- And recreating aquatic habitat to provide high quality spawning and rearing floodplain habitat.
Our command administers an extensive regulatory program that regulates development in wetland areas.
Dredged material is being used to protect and stabilize wildlife habitats. And we participate with other federal agencies to foster waterfowl management and wetlands conservation. Our programs and activities are sensitive to endangered species such as the Least Tern that has numerous nesting areas along the Missouri and Mississippi rivers. We have been gathering data for about a decade, have taken steps to minimize adverse impacts from project activities, and are analyzing long-term effects of engineering work on tern nesting habitats.
The endangered Pallid Sturgeon has also received considerable scrutiny. In 1991, seven pallid sturgeons were captured on the Atchafalaya side of the Sydney B. Murray Hydroelectric Power Station just upstream of the Corps' Old River Complex. Concern developed that sandbar dredging at the entrance channel to the station could pose a threat to the species. The Corps is working with the U.S. Fish and Wildlife Service on studies to better determine the range and location of the sturgeons.
Since 1981, MVD has been engaged in a comprehensive environmental program to develop information on natural resources within the unprotected Mississippi River corridor from Cairo to the Gulf. Major objectives have included conducting an inventory of some 1 million acres within the floodplain and develop environmental design guidelines and criteria for engineering works. We have used GIS Technology to inventory and describe aquatic and terrestrial habitats, elevated our understanding of endangered species, and actively redesigned dike fields and revetments to avoid adverse impacts and enhance some aquatic populations. Thus, the river and the valley's environment continue to challenge the Corps and its allies. The Mississippi remains in some ways both inscrutable and unpredictable.
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