LIANE HANSEN, Host: In Louisiana, the Army Corps of Engineers opened the Morganza Floodway for the first time in 40 years to protect Baton Rouge and New Orleans from flooding. But as NPR's Greg Allen reports from Baton Rouge, the water is being diverted from the Mississippi into communities along Louisiana's bayous that thousands call home. (SOUNDBITE OF RUSHING WATER)GREG ALLEN: This is truly an impressive sight. Just a few minutes ago, the Army Corps of Engineers opened the first gate in the floodway here on the Morganza. I'm standing on top of the spillway here. We're seeing huge cascades of whitewater come through the gate. C: This is a historic day. It's a historic day not only for the entire Mississippi River, but for the state of Louisiana.ALLEN: Fleming says the Morganza is being opened to keep stress off the Mississippi levees that protect Baton Rouge and New Orleans. C: And we'll take approximately ten thousand cubic feet per second off the top of the Mississippi River. ALLEN: That's just a fraction of what the Morganza can handle. Even when the river crests in this area late next week, the Corps expects to open just a quarter of the floodgates. Fleming says the Corps will open the gates slowly - just one or two at a time - for a few reasons. One is to protect the spillway. C: The water will come out of here pretty quickly. You don't want to scour the backside of this structure. From an environmental perspective, obviously there are lots of bear, other kinds of wildlife, and we want to make sure they have the opportunity to get to higher ground. And last but most importantly, we want to make sure that folks have the understanding that water's coming their way and they need to evacuate. ALLEN: About 60 miles south of the Morganza Spillway, the people of Butte La Rose have gotten the message. At the Sacred Heart of Jesus Catholic Church, Teddy and Michelle Wyatt, along with their friend Clo Comeaux, were stacking pews from the church on a trailer. M: We all volunteered to...M: Help one of our churches. M: ...take everything out, to salvage what we could.ALLEN: What have you taken out so far? M: The pews, the altar, the cross, you know, just...M: Anything that was movable. M: AC units, anything that could be damaged in the flood, we're moving everything out.ALLEN: Down by the levee, a group of trustees - prisoners from the St. Martin Parish jail - are working to fill sandbags to protect public and private buildings. They're being supervised by Clayton Landry with the sheriff's department. He says it's been a busy week in Butte La Rose. M: People are trying to move out, move their gears out of their homes and camps and, you know, save as much as they can, you know. ALLEN: Is it your sense people are going to be leaving? That people aren't going to stay? M: No. The sheriff hasn't announced a mandatory evacuation yet, but as soon as the water rises, they will announce it.ALLEN: But Corps General Michael Walsh says it's important that hundreds of workers with the Corps and other agencies keep patrolling the levees to watch for warning signs. History, he says, shows the price of failure. ALLEN: There was an 80-mile width of water covering five states from the '27 flood. So, any type of failure or any type of concerns from that regards in regards to underseepage or overtopping we're going to be on rapidly. And I'd ask you all to remain vigilant.ALLEN: Greg Allen, NPR News, Baton Rouge. NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.