While the Corps of Engineers has started to open the Bonnet Carré Spillway above New Orleans, the agency has asked permission but has yet to decide whether to open the upriver Morganza Spillway to divert the floodwaters from the Mississippi's main channel.
Maj. Gen. Michael J. Walsh, president of the Mississippi River Commission and commander of the Corps' Mississippi Valley Division in Vicksburg, decided to open Bonnet Carré, 30 miles north of New Orleans, on May 9 and will decide if and when to open Morganza, near Morgan City, La., possibly by May 14.
Morganza can divert up to 600,000 cubic feet per second (cfs) of water through central Louisiana to the Gulf of Mexico. The Bonnet Carré, which spills water into Lake Pontchartrain, can handle as much as 250,000 cfs. If both spillways are activated, it would be the first time they were used simultaneously.
“We are in historic times. Over the last two weeks we have received over 600% of rainfall,” Col. Vernie Reichling, the Corps' Memphis District commander, said at a May 8 news conference.
The Mississippi was moving at almost two million cfs, he said, enough to fill a football field 44 ft deep each second.
The river crested at a less-than-projected 47.8 ft in Memphis about 2 a.m. on May 10 and eased back to 47.4 ft by 8 a.m. Upriver at New Madrid, Mo., over a 24 hour period, the water level receded 0.33 in. to 47.1 ft and, at Tiptonville, Tenn., 0.42 in. to 47.1 ft.
Downriver, communities in Mississippi and Louisiana are preparing for the same thing Memphis has faced for several days: backwater flooding by rivers such as the Yazoo that can't empty into the flooded Mississippi.
Corps crews are doing more levee inspections, watching for sand boils, seepage and slides, said Kavanaugh Breazeale, Corps spokesman in Vicksburg.
In Louisiana, the National Guard joined the Corps to haul 16 trailers of Hesco baskets and sandbags to the Bayou Boeuf area and near Morgan City.
Opening Morganza will flood the Atchafalaya River basin in central Louisiana but prevent more massive flooding downstream. Similar to last week's dynamiting of the Birds Point-New Madrid levee in Missouri to protect Cairo, Ill., the idea is to minimize damage by diversion.