Yazoo Delta Backwater Flooding

Backwater flooding happens when the Mississippi River is higher (about 43’ at Vicksburg) than the Yazoo River and blocks its discharge.  It takes less rain to raise and keep the Mississippi above 43’ than it used to. (See More Flood for Less Rain.) So backwater flooding and batture flooding inside the levees are more frequent and longer — over three times longer since 2015.  Why? What happened to cause a step change in flooding in 2015? 

The trigger event was the record high 2011 flood.  But the primary cause is a power plant in the river 122 miles downstream from Vicksburg. It began operating in 1990 under a Memo of Understanding (MOU) with the Corps of Engineeers (Corps). It’s just upstream of the Old River Control Complex (ORCC) that was built in 1963 and modified in 1980.  The Corps operates ORCC to control the Mississippi’s flow to keep it from changing course (avulsing) down the Atchafalaya River. (See Wistful Not Thinking.)

The power plant is owned by a renewable energy company.  It’s purpose is to produce green (renewable) electricity, not to control the river. The Corps allocates most of ORCC’s flow to the power plant. This reduces its control of the river.  It also causes sediments to build up just downstream from ORCC that block part of the Mississippi’s channel and create a flow bottleneck.  That bottleneck slows the river’s discharge to the Gulf and causes higher and longer floods for the same downstream flow volume (i.e. the same rain). 

LSU’s Dr. Xu reported the mound of sediments (which I dubbed Mudberg) and the bottleneck in a paper published in 2017. The Corps knew about Mudberg but didn’t report it.  Dr. Xu said Mudberg and the bottleneck and the higher and longer floods they cause will cause the Mississippi to change course in a future big flood. 

The 2011 flood was the highest ever.  But not the longest.  Otherwise it might have caused the course change.  It did sweep more sediments downstream to Mudberg (as big floods do) and made it bigger and the bottleneck smaller and future floods longer and higher.  The first floods after 2011 occurred in a cluster 2015-21 and caused record backwater and batture flooding. 

The 2019 flood was the longest ever and one of the highest.  It likely made Mudberg bigger and the bottleneck smaller too.  So the next big flood will likely be even longer and higher. Every big flood now makes the next one longer and higher.  And so on — until the levees overtop. 

The Corps latest flow line study predicts the levees will overtop — hundreds of miles of mainline levees from above Greenville to New Orleans.  That will be a disaster for the Delta like the 1927 flood.  The Corps hasn’t told landowners about this and other coming disasters.  It quietly shelved the four volume flow line study published in 2019 that predicts them. 

We learned about the looming disasters and the Corps coverups of them from litigation discovery in a suit filed by Mississippi’s Secretary of State in early 2019.  The suit seeks just compensation under the Takings Clause of the Fifth Amendment of the US Constitution for damage to some half million acres of state and private property inside the levees caused by floods caused by the Corps. Over 500 property owners are plaintiffs.  I am one of them.

The suit is hung up in court. It may take years to resolve.  The damages it seeks to recover are just a tiny fraction of the damage and destruction when levees overtop.  The clock is ticking on that catastrophic damage and destruction.  The risk increases every year.  Most people at risk are unaware of the damage and destruction that is coming.  Those who are aware may think the Corps will do something.  The Corps is doing something: it’s studying the looming disasters.  It’s great at studies.  And at not doing something. 

The Corps needs encouragement to do something.  I am writing about this to warn future flood victims and to encourage them to encourage the Corps to do something — and to ask their Senators and Congressperson to help. 

What can the Corps do to reduce the risk and mitigate the damage? Three things: 1) dredge Mudberg,  2) shut down/remove the power plant that cause the sediments that cause Mudberg and the bottleneck,  3) build a structure upstream of the ORCC to take the top off of floods and reduce their height and duration to take pressure off ORCC and levees. (See earlier articles for details.)

It’s time for the Corps to stop the studies.  And stop the coverups.  And do something. 

Kelley Williams

Chair Bigger Pie Forum

November 11, 2025