History of Missouri's levee system

The federal levee system up and down the Mississippi was built in reaction to the devastating flood of 1927, when the local levees that already were built were all that saved many people from drowning. Many lived on the levees for months. Commerce secretary Herbert Hoover's championing of the levee project positioned him to win the presidency.

The New Madrid Floodway was built to keep Cairo, Ill., from flooding. The gap between the levees was maintained because a similar closure made in the St. Johns Bayou caused concern, according to Eddie Belk, deputy for project management for the Memphis District Corps of Engineers.

"It took a long time for the internal drainage to evacuate, and they thought maybe they were better off taking chances with the river," he said.

The corps has studied how flood levels would be affected at communities above the gap. "The closure will have almost immeasurably small impacts upstream," Belk said. "... The volume of water is not that great."

The Flood Control Act of 1954 authorized closure of the gap, and the St. Johns Bayou improvements were approved in 1986. Opposition to at least parts of the plan from environmental groups and agencies such as the U.S. Fish and Wildlife Service and the state Department of Natural Resources have slowed the project.