This is Science Friday. I'm John Dankoski. Ira Flato is away. A bit later this hour,

which animals get gassy the way humans do and which fail to flagellate. Yes, we'll cut through

the stinky science of animal farts. Really, coming up later. But first, the Mississippi River

was once free to meander, flowing where it pleased, doubling back, slicing shortcuts, and forming

oxbow lakes. If you look at a map of its historic channels laid on top of one another,

it looks like a tangled bunch of strings. But then we came along, and we shackled and constrained

the river in a series of dams and locks and levees and channels, forming a river that's much

straighter and much faster than before.

That kind of engineering requires agreement among regions that for everyone's benefit, walls be built to certain heights

to spread the risk of flooding around equally, and that is regulated by the Army Corps of Engineers.

But some districts haven't abided by the rules.

They've fortified their levees, they've piled them up higher with sandbags, which could push floodwaters over to their neighbors elsewhere on the river. They're lobbying the government to keep it that way, too. It's the topic of an investigation by the nonprofit news site ProPublica, and one of the reporters is here with me now. Lisa's song is a reporter at ProPublica. She joins us in our New York studios. Welcome, Lisa, to Science Friday. Thanks for having me. If you live along a levy and you want to weigh in, you can call us 844-724-8255. That's 844-Sai talk, or you can always tweet us at at SciFri. Let's start a bit, Lisa, with the science part of your investigation.

Communities are breaking the rules, and that's putting others at risk. Explain what's happening here. So what happened was a year ago, the Army Corps of Engineers did a survey of hundreds of

miles of levee in the Upper Mississippi River. And what they discovered was about 40% of those levees, about 80 miles, had been overbuilt

by two to four feet. And that meant that these local levy districts had raised their levies by

two to four feet without getting the proper permits from the Army Corps. And so they were basically

breaking federal rules that are in place to ensure that different communities

are treated equally and that one community

isn't adding extra flooding to another community.

Yeah, and talk a bit more about that,

adding extra flooding to another community.

I build my levees higher.

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