LSU pundits ponder as Mississippi River levels hit record low
Published October 27, 2022 at 1:25 p.m
BATON ROUGE — In the month of October, the Mississippi River hit record lows from Illinois to Louisiana. In Baton Rouge, the level reveals a sunken ferry more than 100 years old and the underbelly of the USS Kidd.
“While this is the time of year when river levels are typically low, we don’t typically see anything that extreme. At least five or six locations along the river, including Mississippi, Arkansas and Missouri, have historically low water levels,” said Clint Willson, director of the LSU Center for River Studies, and Mike N. Dooley, PE professor of civil and environmental engineering. “This is because a large percentage of the Mississippi River watershed, which covers approximately 42 percent of the contiguous United States, is either experiencing drought or is experiencing extremely dry conditions. Typically in the fall, at least one or two of the major tributaries of the Mississippi have ‘normal’ flow conditions and the river is not that low.”
Willson and Kory Konsoer, associate professor of geography and anthropology at LSU and fellow of the Coastal Studies Institute, share more insights into what the low tier means for the state and nation.
What does this mean for the country’s economy?
consoer: One environmental impact that could have economic consequences is that the extremely low water levels also allow saltwater intrusion from the Gulf of Mexico up the Mississippi River. Plaquemines Parish and New Orleans use water from the river for municipal drinking water, so this wedge of saltwater stretching upstream is a concern. The US Army Corps of Engineers (USACE) builds a sill on the riverbed near Myrtle Grove, Louisiana to prevent the wedge from moving upstream.
How is it affecting industry, including tourism?
willon: While low river levels have caused some river cruises to be canceled, the biggest economic impact has come from restrictions on shipping traffic — a critical factor in keeping goods and commerce moving on the Mississippi and its tributaries. Below Baton Rouge, the USACE maintains the depth of the navigation channel at a minimum of 50 feet. However, the navigation channel above Baton Rouge is maintained to a depth of at least nine feet. The 9-foot draft allows fully loaded barges, often connected to another 10 or more barges, to move up and down the river reliably and safely. However, the historically low river level limits how much can be loaded onto the barges and/or how many can be towed at one time. This is having a huge impact on the country’s farming community, as over 60 percent of our agricultural exports are transported downriver on barges. Under normal conditions, these barges transport exports to Louisiana ports where they are loaded onto ocean-going ships and then shipped around the world. The inability to load barges and their reduced capacity result in a backlog of grain and other produce. While the farming community will have the greatest impact, the ports of lower Mississippi, which transship the produce onto larger ships and countries around the world that depend on these exports, will feel the knock-on effect.
Can you describe what we are seeing now compared to the normally raging river?
willon: According to the United States Geological Survey, the Mississippi River’s flow at Baton Rouge has been below 200,000 cubic feet per second, or cfs, since early October and is now about 150,000 cfs. In the years that the USACE must open the Bonnet Carré spillway, located just upstream from New Orleans, the Mississippi discharge is approximately 10 times that, i.e., 1,500,000 cfs.
In terms of river level, the Mississippi is between 4 and 5 feet high at Baton Rouge in October. For reference, the high water level of the river is 35 feet and the record height is 47.3 feet.
What do the short and long-term weather forecasts mean to bring the river back to ideal water level conditions?
consoer: Another cause for concern is that climatologists are predicting another La Niña year this winter from December 2022 to February 2023. This has the potential for exceptionally dry winter months in many parts of the Mississippi watershed, resulting in a situation where water is not replenished during the flood season and water levels remain below average in the spring.
What can be done to fix this?
Willson: There is not much that can be done other than accelerated dredging to deepen the fairway for these unusually low river levels. The USACE normally needs to dredge the navigation channel to maintain allowable depths, but the severity of the current conditions means they need to dredge to more locations and/or to greater depths. However, there are some efforts to bring more water into the main river, such as the Tennessee Valley Authority draining more water from two of its dams to supplement the Mississippi’s water level. But this is not a sustainable, long-term solution.
One thing to keep in mind is that little or no rain that falls in Greater Baton Rouge flows to the Mississippi. The stormwater runoff flows generally southeast towards the Amite River and then into Lake Maurepas and Lake Pontchartrain.