Flooding in Arkansas. (Photo via Flickr)

But the Mississippi isn't the only waterway that has Louisiana emergency officials concerned. As the floodwaters pour south, the state is bracing itself for flooding on the Morganza Floodway as well.

Bloomberg reported:

For weeks, the Mississippi and Ohio rivers, swollen by heavy rain and melted snow, have been inundating cities and towns, flooding croplands and disrupting shipping. The Ohio rose to 61.72 feet, a record in Cairo, Illinois, before joining the Mississippi there.

The threat of that flood reaching Baton Rouge and New Orleans has the Mississippi River Commission considering opening the 125 gates of the Morganza Floodway. Built in 1954, the floodway would release 600,000 cubic feet of water per second into central Louisiana and the Atchafalaya River, taking pressure off the Mississippi and the cities downstream, according to the U.S. Army Corps of Engineers.

The decision will be made if the flow at Louisiana’s Red River Landing north of Baton Rouge reaches 1.5 million cubic feet per second, said Ricky Boyette, a corps spokesman. The flow was at 1.46 cubic feet per second today.

[Louisiana Governor Bobby] Jindal said at a press conference today that the decision could come as early as the day after tomorrow.

Residents of Louisiana's capital, Baton Rouge, would be directly affected if engineers corps chose to open the waterway. However, officials say it may be a necessity to prevent extreme flooding in the western part of the state.

The New York Times reported:

“Certainly the people who live in the inundation zone are uncomfortable and unhappy,” said Maj. Gen. Michael J. Walsh, commander of the Mississippi Valley division of the Corps of Engineers. “But I think most of them recognize that there is this possibility.”

The opening of the spillway, which sits upriver from Baton Rouge, is part of the corps’s vast effort to control what General Walsh called “the flood of the century,” an operation that includes relief valves all along the river’s journey down to the gulf. In many cases, these valves, like the flooding-by-design of over 200,000 acres of farmland here in the Mississippi Delta, are part of the least-bad option, a way to prevent damage at a far greater scale.

Downriver, in New Orleans, residents have also started to prepare for higher water levels. Though officials said they're confident that actions upstream would relieve pressure on the levees near the mouth of the Mississippi, sandbags stretched along the riverfront.

The flooding is expected to cause billions of dollars of damage when the waters begin to recede. More than 3 million acres of farmland have been swamped and tens of thousands have been forced to evacuate their homes.