Steve Maley

Map of oil and gas wells. State unknown.

I’m not sure most people realize that we are just one major flood event away from the Mississippi River permanently changing course in Louisiana. One that takes a new path to the Gulf, 120 miles west of its current delta. In this post, I present the growing geological and scientific evidence for this looming avulsion. This isn’t some conspiracy theory, but a well studied and well documented course correction that is way overdue. While the dynamics of such a geological shift have been building for a couple hundred years, we’ll start this story in 1927. It is then that Louisiana experienced one of the worst floods in its history, when the Mississippi River overflowed and inundated parts of Baton Rouge, New Orleans, and all the towns along its banks. This devastation prompted Congress to enact the Flood Control Act of 1928, and the U.S. Army Corps of Engineers (Corps) proceeded to build a much bigger and stronger levee system along the river all the way to the Gulf. The Mississippi River does not like to stay in one place for too long, and has been planning its escape from these levees ever since. Just waiting for the right time to exit its current predicament and embark on a permanent journey down… the Atchafalaya River. You see, the Mississippi River naturally changes course in Louisiana about every 800-1,200 years. In fact, southeast Louisiana is just one big alluvial valley of meandering deltas historically formed by this river. The process goes like this - Sediment slowly builds over time on the bed of the river. The river elevation rises above its surroundings. Eventually, the law of gravity wins and the river chases the lower gradient. A new river path is forged and a new delta is formed. The pattern repeats itself. This is called an avulsion and can happen over time or in a single night. So when was the last time the Mississippi River changed course? About 800 years ago. Not only is it due for another switch, but this avulsion process has now been accelerated by the construction of levees, as even more sediment stays confined within its banks. But it’s not just a calendar that suggests an avulsion is coming. There are at least 4 observable signals that the Mississippi River is ready, right now, to take the Atchafalaya route… 1) It already does flow down the Atchafalaya. Back around 1900, about 12% of its water flowed naturally into the Atchafalaya River via an old river cut that was opened in 1831. By 1950, the flow was up to 30% and increasing. The Mississippi River Commission conducted a study at this time and concluded that the Mississippi River would be permanently captured by the Atchafalaya River in about 25 years. In response to this alarming study, the Corps hired Hans Albert Einstein to help design what is known as the Old River Control Structure (ORCS) at this old river cut to try and manage the situation. When completed in 1963, Congress set the maximum flow rate down the Atchafalaya path at 30%, and has held that controlled level ever since. 2) From a geological standpoint, it’s already a done deal.  The path down the Atchafalaya River to the Gulf is about 174 miles shorter than the path the Mississippi River is currently on. The Atchafalaya is also 20 feet lower in elevation at the ORCS connection. Only this man-made structure complex is preventing what gravity would have done a long time ago- send the water down the shorter, steeper path. Thanks to the ORCS and levees, the Mississippi river is being forced down a path that no longer makes any geological sense. 3) The sediment tells us so. A team of LSU researchers have been measuring sediment build up in the Mississippi River for a few decades now and have learned that nearly 70% of the river’s sediment it carries never makes it all the way to the gulf.  That’s about 70 million tons of sand falling to the bottom of the riverbed every year. This is because the long, flat path the Mississippi River is on slows the current down, allowing the sediment time to settle. This problem compounds itself as the river floor elevation continually goes up and gets higher and higher than the surrounding land. To be more specific, these LSU researchers found that the Mississippi River floor just downstream of the ORCS has risen nearly 35 feet in the last 30 years. 4) The Atchafalaya River is ready for it. The Atachafalaya River has been doing the opposite of the Mississippi River. In the last 30 years this river has deepened by 12.5 feet and its banks have widened considerably. It’s long since captured all of the Red River’s waters from the Mississippi River and is now ready to fully handle and accept all of the Mississippi waters as well.  The only thing intervening - the man made Old River Control Structure. So how long can the ORCS hold the river from completely switching course? It nearly didn’t in 1973. Following excessive spring rains in the Midwest, the Mississippi River rose to near record levels and was moving more water through the 10 year-old structure than what it was designed to handle. An eddy formed on the back side of the structure and started pulling sand from under it. Parts of the ORCS began to collapse and a hole formed underneath it that was 300 feet wide and 60 feet deep. The situation unfolding was so catastrophic that the Corps of Engineers, using barges, dumped rocks into the hole for weeks starting on that day. The foundation was gone and the structure’s piers were the only thing preventing a total collapse. Miraculously the ORCS was able to keep standing through this event, though the situation was “touch and go for some months” according to the Corps District Engineer. Some historic accounts state that we were within hours of losing the Mississippi River to the Atchafalaya. To this day, the ORCS has not been fully restored from the 1973 flood. It was so compromised that the Corps instead built an auxiliary structure next to it to take pressure off it. The ORCS, still to this day, is rated to handle 15 feet less head of water than what it was rated for at the time of the 1973 flood. This was the Mississippi river’s test. Had it destroyed the ORCS in 1973, it would have permanently switched course down the Atchafalaya River. There is no way to reverse that much water at that elevation gradient. The Mississippi River as we know it through Baton Rouge would be reduced to nothing more than a small bayou. Saltwater from the gulf, no longer being held back by the river, would come up all the way to New Orleans. Studies show that the city’s drinking water would be toast in 2 weeks. Global shipping that use the river would be halted.  On the Atchafalaya side, Morgan City would be completely underwater, perhaps permanently. The economic cost of such an event is hard to comprehend, though the State of Louisiana has been studying such a scenario ever since the 1973 flood. Since then, the Corps has built a couple of contingencies at the ORCS to help thwart such an event from happening again. Aside from adding the auxiliary structure that we previously mentioned, a hydro power plant was also built in 1990 to take more pressure off of the old ORCS. These 3 man made structures at this vulnerable spot – the ORCS, auxiliary structure, and power plant- are all there is to stop the worst economic disaster in the U.S. history from happening. A spot known in the scientific community as the Achilles heel of our country. But here is the final twist… While all this focus and attention has been on the ORCS complex area, the Mississippi River may have it’s eyes set on making this jump somewhere else. It’s called the Widow Graham Bend and it’s a small section of levee about 13 miles upstream from the ORCS. This is the other door that is being overlooked (at least in the mainstream media). This Bend is a sharp turn in the river with a cross-valley slope that is 3 times greater than at the ORCS. The Mississippi River easily took out this section of levee in the 1927 flood.  Back then the river wasn’t ready to make the full jump like it is now, and the levee was reconstructed.  We haven’t had a flood of the 1927 magnitude since… If this story interests you, I encourage you to read or listen to “Beyond Control” by James Barnett.  The latest edition just came out in 2024. James goes into much more detail of the LSU research and the dynamics that are shaping this coming avulsion. He also makes a very compelling case for the switch happening at the Widow Graham Bend.  I find it all very fascinating. If you made it this far, thank you for reading. This was fun to write and I hope I made it worth your time 🙂