Designing the Bayous: The Control of Water in the Atchafalaya Basin, 1800-1995

Chapter 7. The Old River Problem

Chapter 7 The Old River Problem By THE END OF 1941, contours of the modern Atchafalaya Basin floodway system had emerged. Although the Morganza Floodway intake structure was not yet in place and some gaps remained in the levee system, most of the guide levees had been built, as had the levees along the banks of the Atchafalaya River. The East Atchafalaya Basin Protection Levee stretched a bit over 90 miles from Morganza to Morgan City. The upper guide levee for the Morganza Floodway measured 11.6 miles. On the opposite side of the basin, the protection levee for the West Atchafalaya Floodway extended nearly 74 miles from Bayou Courtableau to Bayou Teche. The levee along the west bank of the Atchafalaya River was 77.9 miles long and along the east bank, 51.9 miles. Additionally, levees bordered Wax Lake Outlet, which was almost completed except for the construction of power lines and railway and highway bridges. The Corps had encircled Melville with a full dimension ring levee and at Simmesport was improving a subgrade emergency ring levee it had earlier constructed. The agency finished constructing the front levee and floodwall for Morgan City by the end of the year. To improve and regulate drainage, as authorized in the 1936 Overton Act, the Corps was also constructing a floodgate at Charenton (to regulate the flow between the Atchafalaya Basin and Bayou Teche) and control structures on the east and west diversion canals for Bayou Courtableau. Intermittent dredging continued on various channels. Although over 128 million cubic yards had been dredged in the Atchafalaya Basin by June 1941, the Corps estimated that the work was not yet half finished. The dredging included the creation of eight channel cuts by 1941: Butte La Rose, 3.4 miles; Cow Island, 0.4 miles; Lake Fausse Point, 9.7 miles; Bayou Chene, 1.2 miles; Whiskey Bay, 9.6 miles; Lake Mongoulois, 4.1 miles; Chicot Pass, 11 miles; and Blind Tensas, 1.5 miles.1 In a sense, the Corps of Engineers had turned the Atchafalaya Basin into an elaborate plumbing system. Perhaps unintentionally, the Corps reinforced this perception when it printed a diagram of the Mississippi 208 Designing the Bayous The Mississippi River Commission published this 1952 schematic map showing the distribution ofthe project flood. The Old River Problem 209 River and Tributaries Project. The drawing showed the volume of inflow during a project flood coming from the Mississippi's western and eastern tributaries and the amount of outflow exiting through the river's mouth, the Bonnet Carre Spillway, and the Atchafalaya Basin. Using mainly angles and straight lines, the illustration could as easily have been a diagram of an urban stormwater system. It was a closed system; like water in a pipe, the project flood flowed through this system under the direction of the Corps of Engineers. To the public, the diagram expressed confidence that the lower Mississippi was either under control or soon to be. Yet, as the years passed, the engineers became aware that disaster threatened. Nature Takes the Low Road BEGINNING IN TI-IE EARLY NINETEENTH CENTURY, the engineers who fashioned the levees along the Atchafalaya River and, after 1928, around the basin itself became increasingly concerned over a potential cataclysm: that the Mississippi River would abandon its present course and redirect its entire flow into the Atchafalaya River channel. At best, New Orleans and Baton Rouge would be ports on a saltwater estuary that constantly required dredging. Saltwater intrusion from the ocean would totally destroy New Orleans' water supply, substantially alter the natural environment, and possibly render the Crescent City uninhabitable .2 The ability of large ocean-going vessels to reach Baton Rouge would be problematical, depending on the Corps' ability to dredge a deep enough channel and the willingness of the federal government and local interests to pay for it. As for Morgan City, its survival would be a miracle. In 1812 Army officer Amos Stoddard had cautioned that the Atchafalaya might capture the Mississippi once the raft obstructing the Atchafalaya was removed. Then Captain Shreve made his cutoff at Turnbull Bend in the 1830s. The Atchafalaya River raft stopped growing, but less Mississippi River water entered the Atchafalaya. Instead, the water remained in the main stem channel and continued on past New Orleans to the Gulf of Mexico. However, after state engineers cleared the Atchafalaya of the raft's last remains, just...