The $450 million spent on repairing levees locally after the 2011 Mississippi River flood has paid dividends this year, allowing the 2016 winter flood to come and go with little damage expected, the U.S. Army Corps of Engineers reports.
About half of the estimated $250 million of repairs needed in the New Orleans Corps district after the current high water likely will go toward dredging out river sediment from the navigation channels — primarily in Southwest Pass, said Mark Wingate, deputy district engineer for project management with the Corps’ New Orleans district.
Five dredges are working in Southwest Pass, the primary navigation channel of the Mississippi River, to keep up with the greater amount of sediment being deposited there, he said.
Other repair work could include improvements to the channel by placing structures along the shore to stop erosion, repairs to the levees themselves or repairs at flood control structures such as Bonnet Carre or Morganza.
The costs are just estimates now because high water in the Mississippi and Atchafalaya rivers has been going on for several months now without much of a break.
“The river has never receded, to this point, to reveal the extent of the damage,” Wingate said.
Based on pre-flood inspections, the daily inspections going on now and the number of “trouble” spots the Corps is monitoring, the estimate for the New Orleans district is between $250 million and $300 million for work in 44 areas.
Some areas have already been addressed. They include work at a guide levee at the Morganza Spillway and expanded channel dredging in Southwest Pass, Wingate said. The number of “hot spots” is lower than in 2011, and there are no areas the Corps is concerned about becoming a hazard.
In comparison, the 2011 flood had the New Orleans district tracking about 600 areas of concern or hot spots along the levee system. In the 2016 winter flood, there were 287 areas of concern, and the Corps is watching about 100 hot spots.
Most of these areas of concern deal with water seeping under the levee or sand boils, but none impact the integrity of the levee itself, said Ricky Boyett, chief of public affairs for the Corps’ New Orleans district.
“We have no areas now that we would deem any higher than a low priority,” Boyett said.
The 2016 winter flood got started in late December, and by Jan. 10, the Corps started opening the gates at the Bonnet Carre Spillway. At the river’s peak, 210 of the 350 bays had to be opened to relieve pressure on river levees downstream.
The river crested at 43.3 feet in Baton Rouge, while the crest in New Orleans was kept at 17 feet by the opening of the spillway. All of the spillway’s bays were closed again by Feb. 1.
The beauty of the Mississippi River and Tributaries Project, Wingate said, is that there was a major flood early this year and most people didn’t even notice it.
Just a month after the Bonnet Carre was closed, Mississippi River levels were on the rise again in early March, and the river crested at 38.47 feet in Baton Rouge. On Friday morning, that level was down to about 38.2 feet, 3 feet above the official flood stage.
In New Orleans, the river got up to 15.24 feet on March 21 and was still above 15 feet on Friday, with a slow decline expected.
When the river reaches 15 feet in New Orleans, all work within 1,500 feet of the levee is halted from Baton Rouge south.
In New Orleans, the current long-range forecast doesn’t have the Mississippi River getting below 11 feet until April 15. In Baton Rouge, the river could dip below 35 feet by about April 4, although both dates could change depending on rain and snow melt upriver in the next few weeks.
Although it looks like this latest pulse of water is working its way out of the system, there’s always the possibility for more because a bit more rain is expected this year than during a typical spring.
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