Swollen Mississippi River continues to threaten Louisiana

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Levees on the Mississippi River have been stressed by high water levels for months. Photo courtesy of the AP.

Levees on the Mississippi River have been stressed by high water levels for months. Photo courtesy of the AP.

The river that many expect to provide relief for the flooded Midwest is still running much higher than normal, causing elevated concern in New Orleans, Baton Rouge and everywhere in between as hurricane season hits its peak.

For months, the river has been pushing hard against the levees keeping New Orleans, which is most below sea level, from flooding. For more than 200 days, the Mississippi has been at more than 11 feet above sea levels.

“The big threat is water getting through or underneath,” Nicholas Pinter, an expert on river dynamics and flood risks, told claimsjournal.com. “The longer the duration, the greater the threat.”

The U.S. Army Corps of Engineers is remains confident that the levees are in good condition after improvements were made in 2011. “If there’s a silver lining going into hurricane season with the river this high for this long, we’re entering the hurricane season having done 200 inspections of the levee since February,” Ricky Boyett, a spokesman for the New Orleans office of the corps said.

Inspectors have been checking levees at least twice a week for parked barges, stuck debris or other potential damage. They also look for water seeping through and for sand boils — spots where water tunneling below a levee seems to bubble out of the grand.

The corps places concrete mats on the river bottom in areas likely to be eroded by the river’s current and sand boils are ringed with sandbags until the water pressure on both sides equalizes. Because some permanent repairs can’t be made until river levels drop, dangerous seepage gets stopgap coverage: According to claimsjournal.com, about 63,000 large sandbags have been used since March on one 300-foot-long seepage area upriver of Baton Rouge.

The National Oceanic and Atmospheric Association said a Category 4 hurricane striking the Louisiana coastline could produce a 20-foot storm surge, but New Orleans is more than 100 miles upriver from the coast and the river would be pushing back against the surge. The levees range in height from 20 to 25 feet and the National Weather Service is predicting that the Mississippi will remain at about 11 feet above sea-level this week. For the past three decades, the river has run about 3 to 5 feet high in mid-August. The day before Katrina hit, the Mississippi was running at 3.6 feet.

“I would assume major problems on the river if we had a high river with a Katrina event,” Jeffery Graschel, who is with the National Weather Service’s Lower Mississippi River Forecast Center, said.

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