Morganza Spillway to Open as River Flow Rises to Threshold

The opening of Louisiana’s Morganza floodway today may send enough water to fill a football field 10 feet deep every second across the heart of Cajun country, eventually filling an area almost as large as Connecticut.

Major General Michael Walsh, president of the Mississippi River Commission, has told Col. Edward Fleming to open the spillway when the river’s flow reaches 1.5 million cubic feet per second at Louisiana’s Red River Landing, the U.S. Army Corps of Engineers said in a statement. The flow reached that threshold this morning, according to the weather service.

“We have not opened it yet,” said Ken Holder, corps spokesman.

The spillway, built in 1954, can release 600,000 cubic feet of water per second into central Louisiana and the Atchafalaya River at maximum capacity, taking pressure off the Mississippi and the cities downstream, according to the U.S. Army Corps of Engineers. Corps inundation maps assume the spillway operating at 50 percent of capacity.

The corps expects to release 150,000 cubic feet per second from the Morganza, which is 310 river miles above New Orleans. The opening of the Morganza is expected to drop crests on the Mississippi River from 1 to 2 feet, according to the National Weather Service.

Wall of Water

Louisiana Governor Bobby Jindal said yesterday that the Morganza would be opened gradually and wouldn’t result in a wall of water running the length of the state to Morgan City, 70 miles west of New Orleans, where the Atchafalaya empties into the Gulf of Mexico. He stressed the need for residents to move quickly.

“Now is the time to take action,” Jindal said at a press conference. “We wanted to give people as much advance notice as we can.”

About 2,500 people and 2,000 structures are within the spillway and another 22,500 and 11,000 buildings are vulnerable to flooding when the waters rise, according to Jindal’s office.

When the Morganza Spillway is opened, an estimated 15,000 acres of farmland will be initially underwater in the south-central part of Louisiana along the Mississippi River, Kyle McCann, a spokesman at Louisiana Farm Bureau Federation.

Opening the spillway will also affect Louisiana’s energy production. Inside the threatened area are 2,264 wells that produce 19,278 barrels of crude oil a day, about 10 percent of Louisiana’s onshore total.

Oil, Gas Production

About 252.6 million cubic feet a day of gas is produced in the corps’ potential inundation area, Anna Dearmon, a spokeswoman for the Louisiana Department of Natural Resources, said in an e-mail. She said there is no estimate of how much of this production would be affected.

“We are building earthen, sandbag and Hesco basket levees in Amelia,” said Paul Naquin, St. Mary Parish president, based in Franklin, Louisiana. “In five days we should be OK. We are working 24 hours a day trying to beat the clock.”

A Hesco basket is a container that can be filled with dirt to build a temporary levee.

Naquin said there is also a plan to sink a barge in a bayou to slow down the rising water.

Exxon Dock

Exxon Mobil Corp. shut river dock operations at the refinery in Baton Rouge today after the waters of Mississippi River flooded the facility, Kevin Allexon, a company spokesman said. The plant, second-largest in the U.S. after Exxon’s refinery in Baytown, Texas, remains in production and can process 525,000 barrels of oil a day, according to data compiled by Bloomberg.

National Guard troops and local sheriffs would start going door-to-door in the affected areas warning residents to flee, Jindal said. It would take the water three days to travel the length of the floodway from Morganza to Morgan City.

A voluntary evacuation notice has been issued for Melville, Krotz Springs and Three Mile Lake, according to the St. Landry Parish government. Automated phone messages were being sent to people living in the area.

For weeks, the Mississippi and Ohio rivers, swollen by heavy rain and melted snow, have been inundating cities and towns, flooding cropland and disrupting shipping. The Ohio rose to a record 61.72 feet (18.8 meters) in Cairo, Illinois, before joining the Mississippi there.

Record Crest

Without the Morganza being opened, the Mississippi was expected to crest at 47.5 feet in Baton Rouge on May 22 and 19.5 feet in New Orleans on May 23, according to the weather service. The estimated crests with the spillway open are now 45.5 to 46.5 feet in Baton Rouge and 17 feet in New Orleans.

The record crest in Baton Rouge was 47.2 feet in 1927 and 21.27 feet in New Orleans in 1922, according to the weather service.

The flooding in Tennessee has affected 650,000 acres of cropland in the western part of the state, including 86,000 acres of wheat, said Lee Maddox, a spokesman for the Tennessee Farm Bureau, citing numbers from the state’s farm service agency, a unit of the U.S. Department of Agriculture. Farmers were just getting ready to harvest the wheat, and it’s probably destroyed now, Maddox said.

The Mississippi River system was engineered to absorb a major flood while maintaining flow rates through Baton Rouge and New Orleans to ensure the integrity of levees, according to the corps. The corps wants to limit flow to 1.5 million cubic feet per second at Baton Rouge and 1.25 million at New Orleans, said Ken Holder, a spokesman.

Spillway Use

When the river flows exceed that, the system is designed to have water diverted elsewhere by using the Morganza or the Bonnet Carre spillway outside New Orleans, he said.

Jindal said the corps has asked the State Police to shut the roadway over the Morganza down at 10 a.m. The structure also carries a Kansas City Southern railroad line.

Opening the Morganza may lower the river’s crest in Baton Rouge by as little as a foot, said Bryan Harmon, the city’s deputy public works director.

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