Spillway possibilities discussed at Rotary meeting

Published 12:00 am Tuesday, August 12, 2008


Editor and Publisher

LAPLACE – To so many people in the River Region, the opening of the Bonnet Carre Spillway is simply an exciting event to watch millions of gallons of water suddenly rush from the Mississippi River through the basin towards the lake.

But to Christopher Brantley, Bonnet Carre Spillway project manager, the basin is not only a life-saving device built 70 years ago, but could conceivably be the answer to the coastal erosion problem Louisiana continues to face.

Brantley detailed the work of the Spillway at a recent talk to the LaPlace Rotary Club, and made it clear to the group there that the function of the Spillway is clearly a life-saver for many in the region who would otherwise face flooding prospects when the river rises.

This year the Spillway was opened on April 11, using half of its capacity, the eighth time since being built that the Spillway had been opened.

The U.S. Army Corps of Engineers built the Spillway after the Great Flood of 1927 killed over 500 people, and flooded over 700,000 people from their homes.

Even though the Corps had been responsible for various aspects of flood control in the 19th Century, there was a more serious approach to the matter in 1879 when Congress established the Mississippi River Commission (MRC). The Commission began to work with local levee boards to try and control the annual flooding from the Mississippi River, and the group felt comfortable with what they had done with levees until 1927.

That’s when the great flood brought about a new look at the levee situation, and the Corps of Engineers was directed to find better ways to control the flooding. During the Great Flood of ’27, there were 13 breaks in levees on the river, showing the uncertainty that even they provided.

The Spillway was built after the ’27 Flood and was opened for the first time in 1937, and has since been opened seven more times, including earlier this year when the river was running high again.

The location of the Bonnet Carre was picked at St. Charles Parish since it was clearly an area at which the water peaked. Numerous breaks in the levee there had occurred in the 1800s, and in 1849, there was a 7,000 foot wide break in the levee at that location.

When opened at its maximum, the Spillway can divert 250,000 cubic feet of water per second out of the river, sending it through the Spillway area and on into Lake Pontchartrain.

Brantley said that the Spillway is a vital way to keep flooding from occurring in heavily populated areas such as New Orleans. But he said that the large amount of sediment that comes with the diversion could also become a great way to rebuild some of Louisiana’s eroding coastline further down river.

“The Spillway shows that there is a way to help restore the coastline problem,” he said. “We just have to figure out a way to utilize its features where we need them. For coastal restoration, we need to get that sediment from the river to these key coastal areas that are eroding.”

Even in St. Charles Parish, the large amount of sediment that is left in the Bonnet Carre Spillway has provided dirt to be used for construction and other needs in the region. While the Corps had recently closed the Spillway from digging since most of the dirt had been used, Brantley said that the opening of the Spillway just two months ago has replentished the supply.

“I expect us to allow dirt companies to start getting sand from the Spillway again in probably October,” he noted.

The most recent opening of the Spillway this year on April 11 only utilized half of the capacity to move water, although the maximum opening could be as wide as 7,000 feet. That would incorporate all 350 bays, which are 20 feet wide each and each have 20 creosote timbers keeping them closed.

The decision to open the Bonnet Carre Spillway belongs to Mississippi River Commission President Brig. Gen. Michael J. Walsh, commander of the Corps’ Mississippi Valley Division in Vicksburg, Miss.