The Mississippi River's record run in flood stage at Baton Rouge hit 211 days before ending Sunday afternoon, blowing past the former, 92-year-old record by 76 days.

The Great Flood of 1927, what the Memphis Commercial Appeal once called "the greatest flood in history," set the former record, holding the Mississippi in Baton Rouge at flood stage for 135 days, according to National Weather Service data and a 2001 National Geographic account of the historic flood.

The 1927 flood led to a remaking of the nation's flood control system on the river after it blasted through the levee systems of the day, flooding 2,700 square miles of land and displacing more than 700,000 people across seven states, a U.S. Geological Survey report says.

This year's high water did break levees on the Arkansas, Missouri and upper Mississippi rivers, but the lower Mississippi flood control system that the grew out of the '27 flood held fast, though the historic high water prompted record-long use of the Bonnet Carré Spillway upriver of New Orleans.

Gerald Galloway Jr., a research professor and civil engineer at the University of Maryland who has specialized in water resources policy and disaster resilience, said when levees hold back water as long as they have this year, they are placed under considerable stress.

"You ask a lot of levee to have water up against for a short period of time and, as the levee is pushed for even longer periods of time, it does, as part of its overall integrity, it is certainly challenged," Galloway said.


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Levee districts and the U.S. Army Corps of Engineers have had the system under daily inspections for months. Rene Poche, a Corps spokesman in New Orleans, said the levees will remain under inspection as river levels drop but they appear to be in solid condition.

Rapidly falling river levels can pose a potential risk to levee integrity by releasing the water pressure too quickly, but Poche said Corps officials are not anticipating those kinds of problems with the current slow, steady drop being forecast by National Weather Service.

Poche said a river decline of 2 to 3 feet per day would be a concern.

Gavin Phillips, a meteorologist with the Weather Service office in Slidell, said the river has been falling about one-third of a foot per day in Baton Rouge.

Phillips called that rate not necessarily fast but "a pretty good fall," especially given the volume of water in the Mississippi at Baton Rouge.

In New Orleans, where the river was already below flood stage, water levels have been falling about half as fast as in Baton Rouge over the past few days, gauge readings show.

According to the Weather Service, the river is wider and has a flatter slope in New Orleans than in Baton Rouge and so has slower changes in water levels.

After an extended period of heightened awareness of the river, Baton Rouge has been showing signs of a return to normalcy. City-parish officials plan to clean the formerly flooded "Baton Rouge" letters and other once-inundated areas along the downtown levee path in next week or so.

Still, the 12 months between June 2018 and May 2019 were the wettest one-year period across the contiguous United States in 125 years, the National Oceanic and Atmospheric Administration reported.

The new record average of 37.68 inches broke the old record for any 12-month period by about 1.5 inches, NOAA reported.

The Mississippi and its tributaries drain 41 percent of the nation, and increasing rainfall has a big effect downriver.

Just the difference between the new record number of days in flood stage at Baton Rouge and those in the previous 92-year-old record — an additional 76 days for 2019 — would by themselves rank sixth on the Weather Service's all-time list.

Galloway said he sees these kinds of changes as an unmistakable sign that global climate change is playing a factor in river's flooding, bringing wetter periods over the nation's midsection that send more runoff to Louisiana. 

While other factors have a role, too, including continued development in the floodplains of the Mississippi and its tributaries, the leveeing and channelization of the Mississippi, and changes in the river's bottom, Galloway said one fact is hard to avoid. There's more water.

"I've got to say. I'm a believer in that what gives you the flood is the water," he said.

Putting aside debates about the causes and possible solutions to climate change, Galloway said it is time to start accounting for those changes to the river system. 

Email David J. Mitchell at dmitchell@theadvocate.com

Follow David J. Mitchell on Twitter, @NewsieDave.