AWO Looks Back At Low-Water Fight

The weather, and its effect on river conditions, was front  and center as members of The American Waterways Operators (AWO) gathered in New Orleans February 22–23 for the 2024 combined regions annual meeting.

David Welch and Jessica Smith, both part of the National Weather Service’s Lower Mississippi River Forecast Center, discussed factors that influence conditions on the Mississippi River and its tributaries. The same drought conditions that led to extended periods of low water in both 2022 and 2023 are what led to, among other things, salt water intrusion below New Orleans.

“The Lower Mississippi River’s channel bottom is lower than the Gulf of Mexico,” Welch said, “so when you have low flow over a period of time, you don’t have the momentum flowing down river to keep the salt water from intruding upriver. When you have a long, persistent period of low flow, that salt water encroaches upriver, and after a period, it starts to impact municipal [water intakes].”

In response to salt water intrusion in both 2022 and 2023, the U.S. Army Corps of Engineers built a sill across the riverbed near Mile 64, which served as a barrier to the wedge of salt water moving upstream. The Corps rebuilt the sill last July, then raised and augmented it in September and October 2023, successfully shielding the New Orleans area’s major population centers from dangerously high chloride levels in the process. The flow on the river has since exceeded the 300,000 to 400,000 cubic feet per second needed to push the salt water back down stream, Welch said.

Welch admitted that, looking at long-term river data, there appears to be a shift over the past four decades.

“What we have seen over the last 45 years is a lot more variability,” he said.

That includes both high-flow years and low-flow records, Welch said.

Smith overviewed recent weather trends, including the mild winter this year in the Ohio and Mississippi valleys.

“There’s essentially no snowpack,” Smith said.

Long-range forecasting for the eastern half of the country shows equal chances of a below-normal and above-normal spring, with warmer-than-normal temperatures. Overall, the chances of reaching anything beyond a minor flood stage on the lower river is relatively low, based on current long-range forecasts.

And while neither Welch nor Smith offered a hint at the National Hurricane Center’s 2024 Atlantic hurricane season outlook, Smith did offer that El Niño conditions are expected to weaken through April, May and June, with neutral or La Niña conditions expected in July, August and September during the height of hurricane season. La Niña typically favors tropical development, whereas El Niño conditions often inhibit development in the Atlantic Ocean.

Rear Adm. David Barata, commander of the U.S. Coast Guard’s Eighth District, addressed the group, speaking, in part, on recent low-water seasons.

“Our low-water year this year, I think, is a success story,” Barata said. “I think we took the experiences from two years ago and were able to really employ some of the lessons learned this last season.”

Barata said he was impressed to see the coordination and communication between the Coast Guard, Corps of Engineers and industry that kept cargoes moving safely, despite ongoing low water.

Later in the meeting, AWO’s Lynn Muench moderated a low-water discussion panel that looked at the 2023 low water season and how industry and government agencies, particularly the Coast Guard and Corp of Engineers, worked together to minimize impacts to navigation.

“In 2022 versus 2023, we had a lot less water in 2023, and yet we had a lot less incidents,” said Muench, who attributed that, in part, to recommendations the River Industry Executive Task Force (RIETF) developed for the Coast Guard, Corps and industry.

Panelists included Jay McDaniel with Kirby Inland Marine, Randy Chamness with American Commercial Barge Line (ACBL), the Mississippi Valley Engineer Division’s Pat Chambers and Capt. Keith Doxey with the Eighth Coast Guard District.

Panelists repeated two main takeaways throughout their discussion. First, the manageable impacts of the 2023 low water were only possible because of the lessons learned during the extensive closures and restrictions experienced in 2022. Second, the nation will, at some point, have to deal with its aged dustpan dredge fleet, which was deployed extensively during the 2022 season.

“I’m going to beat this drum everywhere I go,” Chambers said. “Recapitalizing our dustpan dredges. They are the key to keeping the Mississippi River open. They’re maneuverable. They facilitate being able to get in and get out of the cut quickly to be able to pass traffic. Do a little bit, get out of the way to let traffic pass, get back in and do it quickly. Two of those dustpans are 90 years old, and I will tell you that it is a Herculean feat by the greatest operations and maintenance personnel there are out there on the river to keep those vessels working and working as much as they have over these last two years. It’s been phenomenal.”