STEVE INSKEEP, host:
Now, to handle all that water flowing down the Mississippi, the Army Corps of Engineers is opening floodgates north of New Orleans today. This is supposed to divert some of the floodwaters into Lake Pontchartrain and from there to the Gulf of Mexico. This move comes with controversy, which is normal whenever the Corps tries to influence the most powerful of all American rivers.
NPR's Greg Allen reports.
GREG ALLEN: In almost every decision to divert floodwaters, there are winners and losers. With the opening of the Bonnet Carre Spillway, John Lopez of the Lake Pontchartrain Basin Foundation says the loser will be the lake. Within a few days, the brackish waters of the lake will be flushed out and replaced by nutrient-rich freshwater from the Mississippi. That will likely drive out the crabs and fish that normally call the lake home, and promote algae blooms.
Dr. JOHN LOPEZ (Lake Pontchartrain Basin Foundation): The blooms can lead to low oxygen-anoxia or hypoxia in the lake. There have been times when there's been some relatively minor fish kills. It will hurt, in the short term, some of the fishing or swimming recreational activities.
ALLEN: Because of the danger and potential damage posed by the rising waters of the Mississippi, Lopez says his group doesn't oppose opening the spillway. It's a system controlled by floodgates that's been opened sporadically over the years.
It's a much different situation than the floodway activated last week in southern Missouri.
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ALLEN: Over the course of four days, the Army Corps of Engineers blasted three openings in levees on the Birds Point floodway. It helped protect communities and almost immediately reduced the level of the river by a couple of feet. But in doing so, it flooded some 130,000 acres of farmland and forced evacuation of 100 homes.
Army Corps of Engineers Major General Michael Walsh said deciding to activate the floodway was not something he did lightly.
Major General MICHAEL WALSH (Army Corps of Engineers): I've known many of the people who have lived and worked in the floodway for the past three years. I consider them friends, and certainly making the decision to put this in operation was a difficult decision.
ALLEN: One reason farmland near the Mississippi is so productive is precisely because it's received regular flooding from the river. Activating the floodway was part of a plan that's been part of the Mississippi's flood control design for more than 80 years. But although it's long been in place, it's rarely used. The last time was 74 years ago. At that time, like now, the decision was met with protests and lawsuits.
Charles Camillo is a historian with the Mississippi River Commission. He's studied the transcripts of the congressional hearings after the historic 1927 Mississippi flood that led to the creation of the current flood control plan. Even then, Camillo says, there was opposition.
Mr. CHARLES CAMILLO (Historian, Mississippi River Commission): But it was best characterized, I think, by Congressman Dewey Short. He said, you know, the people of Southeast Missouri do not want to become the dumping grounds to protect Cairo, Illinois, as much as we love Cairo, Illinois.
ALLEN: Craig Colten is a professor of geography at Louisiana State University. He says it's the nature of the work the Army Corps of Engineers is called to do that puts them at the center of one controversy after another.
Professor CRAIG COLTEN (Louisiana State University): Whenever you build structures to handle floods, you're walking that fine line between providing protection and failing to provide protection. And so of course the Corps are going to be a lightning rod for any - either failures or even successes that on a rare occasion cause damage.
ALLEN: For the Corps, any criticism they're facing over how they're handling flooding on the Mississippi pales in comparison with the public scourging they received following Hurricane Katrina.
In the nearly six years since, the Corps has done much to upgrade flood control - and its image - in New Orleans. Post-Katrina, Colten says, among the changes he sees in the Corps, it's careful now to downplay the level of protection provided by its flood control efforts.
Mr. COLTEN: They're trying not to present their levees as infallible and as providing 100 percent protection. So maybe that's the one lesson: they perhaps exhibit a little less hubris than they did in the past.
ALLEN: As the Mississippi flooding moves downriver, the Army Corps of Engineers says in some areas it may even exceed levels seen in the historic 1927 flood. It's a reminder and a warning that even with the best flood control measures, living next to the river means sometimes getting wet.
Greg Allen, NPR News.