On Saturday, May 14, at 3:00 pm Central Daylight time, a hydro-historic event occurred: the U.S. Army Corps of Engineers (USACE) opened the Morganza Floodway to control flooding on the Lower Mississippi River for the first time since 1973 (See a picture of the first rush of water). The Morganza is part of a complex of floodgates, weirs, levees, and diversions built and operated by USACE to keep the Mississippi River in its current channel – preserving trillions of dollars of industries and infrastructure – rather than doing what it has tried to do since the 1860’s and follow the Atchafalaya to the Gulf.
Flow on the Mississippi this year is reaching rates that are being compared to those that caused the Great Mississippi Floods of 1927, which inundated 27,000 square miles, fueled a wave of migration, and spurred Congress to order USACE to construct the world’s largest system of levees. Opening the Morganza will divert flow from the Mississippi to the Atchafalaya River, adding to flow already being diverted from the Mississippi to the Atchafalaya through the Old River Control Structure. If all goes according to plan, this will reduce flow through Baton Rouge and New Orleans to manageable levels. Unfortunately, it will also displace thousands of people residing along the Atchafalaya, but it is better than Plan B.
There has been much debate over the control of the Mississippi. On the one hand, USACE’s efforts to control the natural migration of the river have been called arrogant and ultimately futile. On the other, this engineering achievement has been hailed as a marvel that protects cities and industry along the American Ruhr Valley. Regardless of your position, I highly recommend the essay by John McPhee as background reading.
2011.05.14.2025 EDT: edited to include Plan B