January 2026 is the tenth anniversary of the 2016 Mississippi River freak winter flood. It was
only the third such flood ever recorded. It flooded habitat inside the levees and along the river
and caused the deer season to close early.
It was the second of six consecutive major floods — a first-time-ever event. They destroyed
millions of acres of bottomland hardwood ecosystems inside the levees from below Natchez to
above Greenville. The river was above flood stage at Vicksburg and other reaches three times
longer in the 5 years after 2015 vs before. The 2019 Delta backwater flood was the longest
ever.
The cluster of long, high floods was caused by a sediment bottleneck that reduces the river’s
flow to the Gulf and makes floods higher and longer. More flood for the same rain and less
drain.
In 2019, the US Army Corps of Engineers (Corps) published a four-volume study (Mississippi
River and Tributaries Future Flood Conditions). It predicts that future floods will overtop
mainline levees. You may not know about the study. The Corps quietly shelved it. And doesn’t
talk about it. It deserves your attention though if you live in Greenville, Greenwood, Clarksdale,
or another city that flooded in the great 1927 flood. The Corps says it will happen again.
Congress put the Corps in charge of flood control (1928 Flood Control Act) to prevent another
1927 flood. The Corps has spent billions on levees and flood control projects under its
Mississippi Rivers and Tributaries Project (MRTP). But the bottleneck will cause levees to
overtop anyway. The Corps is responsible for creating the bottleneck. This may why it doesn’t
talk about it.
When flooded landowners inside the levees testified before the Mississippi River Commission after the 2016 flood, the Generals in charge of flood control projects said it was due to more rain. They didn’t mention the bottleneck — although they had known about it since the record- high 2011 flood.
In 2018, flood victims learned about it from a paper published by LSU’s Dr. Yi-Jun Xu in late 2017. He said sediments created the bottleneck after 1990. And that it caused the river to rise and could make it avulse (change course) to the Atchafalaya River in a big flood.
The river began to avulse in the flood of 1950 and was predicted to change course completely by 1975. The course change would be disastrous for a million people in the Atchafalaya Basin. It would shut down the Port of New Orleans and Mississippi River Commerce and the petroleum and petrochemical complexes at Baton Rouge and New Orleans. It threatens the nation’s security and economy. So Congress authorized construction of the Old River Control Complex (ORCC) just downstream of the Mississippi-Louisiana line to prevent it.
The Corps built the first stage of the ORCC in 1963 and repaired and expanded it in 1980 after the 1973 flood. It diverts 23% of the Mississippi’s flow to the shorter, steeper Atchafalaya to discharge to the Gulf near Morgan City, LA. It sends the remaining 77% meandering to the Gulf at New Orleans via the longer, flatter main channel. It was carefully designed to minimize sediment buildup in the main channel that hydrologists knew would naturally occur due to diverting part of its flow.
It operated successfully with little increase in sediment depositions until 1990. Then Corps commanders, for unknown reasons, agreed to the addition of a small hydroelectric plant (Sidney A. Murray Hydroelectric Plant) upstream of the ORCC and to integrate its operation with the ORCC. The power plant is privately owned. It has nothing to do with flood control. Its power output is insignificant (less than 1% of Entergy Louisiana’s, which takes it).
But it caused a huge increase in sediments and created the bottleneck that makes floods higher and longer — and that increases the risk of avulsion and levees overtopping. The plant started up in 1990. The Corps sends 80% of the Mississippi’s flow through it that it had previously diverted through the ORCC to the Atchafalaya.
The flow it sent to the ORCC was rich in sediments. The flow it sends to to the power plant has almost none because they damage the power plant’s turbines. This change increased sediments left in the main channel. Over 5 million tons of excess sediments fell out, clogged the channel, and created the bottleneck.
The bottleneck gets incrementally worse every year and much worse when big floods (e.g., 2011) sweep sediments there. That’s why Dr. Xu says the Mississippi could avulse in a big flood. And why the Corps predicts levees will overtop.
Flooded landowners led by Mississippi’s then Secretary of State, Delbert Hosemann, sued for compensation for flood damages under the Fifth Amendment of the Constitution in early 2019. Their attorneys learned about the power plant during discovery.
Why won’t the Corps dredge the bottleneck or require the power plant to dredge it? Flood victims inside the levees would like to know. Future flood and avulsion victims might too if they knew about it. Mississippi’s US Senators who have Corps oversight authority might too.
Corps Generals stonewalled Lieutenant Governor Hosemann when he asked why Mississippi’s 16th Section Properties were flooding more. He could hold a Mississippi Senate Committee hearing and ask Corps officials to explain the bottleneck. It might alarm some uninformed future flood victims. It might prompt overdue action to dredge and remove the bottleneck.
It may take a decade to remove the bottleneck, restore Mississippi’s flow to the Gulf, and reduce the risk of levees overtopping and avulsion. Corps defenders say I’m Chicken Little for warning about this in the middle of a drought. But a drought is the best time to dredge.
What if Chicken Little and Dr. Xu and the Corps flow line study are all right? What if Dr. Xu’s big flood happens before the bottleneck is removed? And before the Corps quits studying and hiding it?
Big floods happen about every decade. The last one was 6 years ago.
6 comments:
There's a reckoning unfolding with water infrastructure overall. Water utilities, dams, flood control projects are all old (some +100 years) and have, almost without exception, been neglected and underfunded. The results of that mismanagement will be horrific.
Costs go up and paper pushing goes up.
Levee and flood control building goes way down and takes forever.
We need to build more and better levees higher and faster or we are in real trouble.
Thank you for having the insight and courage to publish this. What can citizens do to ensure that the responsible parties are aware and take action?
pump some water in Mississippi river to California.
It's the glaciers upriver that are melting due to global warming, right Algore?
The Corps is corrupt to the core.
Post a Comment