Levees Not War

“The President of the Mississippi River Commission Maj. Gen. Michael J. Walsh has directed the New Orleans District Commander Col. Ed Fleming to be prepared to operate the Morganza Floodway within 24 hours. The operation will include the deliberate and slow opening of the structure.” —U.S. Army Corps of Engineers announcement, May 13

On Saturday at 3:00 Central Standard Time the U.S. Army Corps of Engineers opened the first 25-foot-wide bay of the Morganza Spillway for only the second time in the structure’s nearly 60-year history. The last time was in 1973. The primary objective of the opening is to reduce the likelihood of the swollen Mississippi River flooding the port cities of Baton Rouge and New Orleans downstream.

If the Corps had not opened the Morganza, reports Mark Schleifstein of the Times-Picayune, the river would have crested at 19.5 feet at New Orleans, “only a half-foot below the tops of levees and floodwalls in the city.”

The Corps announced that, at least for now, the Morganza opening will be smaller than was suggested earlier: present plans call for 125,000 cubic feet of water per second to be diverted into the Atchafalaya River and Basin instead of the earlier projection of 300,000 cfs. That is less than one-quarter of the total capacity (600,000 cfs) that the spillway could divert if all 125 bays were opened. The opening of the bays will be gradual, beginning with one or two at a time in order to let the Atchafalaya fill as gently and slowly as possible; there will not be a torrent or tsunami rushing into the Atchafalaya Basin.

Flooding will still be considerable, however, over some 3,000 square miles of Acadiana. In some areas the water will be 25 feet deep. About 25,000 people will be affected. Governor Jindal has directed parish administrators in the Atchafalaya Basin parishes to direct people living in the flood plain to evacuate. “Now is the time to take action. Don’t delay. Don’t hope something will change.”

The higher water is expected to reach Morgan City within three days of the opening.

It is predicted that the Mississippi will crest at New Orleans on Monday, March 23.

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There’s a certain trepidation in writing that headline, but . . .

Despite over $2 billion in damages, possibly to reach $4 billion from the Mississippi River Flood of 2011, including dramatic flooding upriver around Cairo, Memphis, and Vicksburg—and despite scary images and headlines on screen and paper—the city of New Orleans should be safe from inundation from the historically high waters now coursing down the Mississippi toward the Gulf. The flooding is the result of normal springtime snowmelt compounded by record rainfall from two major storm systems across the U.S. during April. (See Mississippi River watershed map below; click to enlarge.)

The U.S. Army Corps of Engineers has already begun opening the Bonnet Carré spillway upriver from the city (photo below). There will be flooding in the Atchafalaya Basin—possibly around 3 million acres—once water is diverted from the Morganza Spillway, a decision that is expected soon from the Corps of Engineers. And deep-draft shipping may be temporarily suspended by the U.S. Coast Guard if water levels rise to just a little higher than they are now; Americans “upriver” may experience a spike in gas prices as supplies are temporarily interrupted by the halting of oil tanker traffic between Baton Rouge and the Gulf.

Read the Headlines with Some Skepticism

Under the ominous headline “Mississippi River Flooding in New Orleans Area Could Be Massive if Morganza Spillway Stays Closed,” the New Orleans Times-Picayune reported on Wednesday that based upon the best information available from the Corps of Engineers, the staggering volume of water making its way down the Mississippi could cause “levee failures and massive inundation of metro New Orleans, worse than Hurricane Katrina, if the Morganza spillway is not opened to divert river water down the Atchafalaya basin. The bad news for people living along the Atchafalaya: the Corps of Engineers predicts they will flood in either case.” Although the article itself was measured, not alarmist, the headline implied there was a possibility that the Corps might decide not to open the Morganza Spillway. Another headline warned, “Corps Officials Fear Flooding.” Note to the reader: It is the Corps’ job to fear flooding and to try to make sure it doesn’t happen.

Now, reporters don’t write the headlines, and the body of an article is often less alarming than the headline crafted by some news editor. But “Flooding Could Be Massive” sort of got our attention, so we checked around.

An engineer friend in the New Orleans area who knows people at the U.S. Army Corps of Engineers says the Corps is monitoring the situation very closely all along the river, per established protocol, and just waiting for Major General Michael Walsh to give the word about opening the Morganza Spillway. Major General Walsh is president of the Mississippi River Commission and commander of all USACE districts along the river. Times-Picayune environmental reporter Mark Schleifstein writes that General Walsh is expected to announce his decision to open the Morganza spillway between Friday and Tuesday (May 13 and 17).

Our engineer friend says, “Walsh is going to wait until the last possible moment to give the order just in case something changes in the river or they [the Corps] discover a better alternative. And when I say, ‘last possible moment,’ that is taking into account the timeline between when the order is given and everything that has to happen to safely open the structure. This stuff is really well thought out. The hydraulics, structures and levee engineers there have been working this 7 days a week for the past two weeks. . . . New Orleans is safe for now. Never say never, but we have no reason to panic as of right now.”

[ Click here for City of New Orleans Emergency Preparedness / Flood Fight information ]

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