I would wake up in the middle, like three o'clock, and I'm in a pool of sweat, and I'm crouched on all fours,

trying to figure out what goddamn rapid I'm rowing in the Grand Canyon.

This is Ken Sanders. He's telling me and my producer Abigail about a river trip he took down the Colorado River in 1983.

That year, there was a giant flood. Water levels in the Grand Canyon were six times higher than

normal. Rapids turned into 20-foot standing waves. Ken couldn't even swim, but he never missed an

adventure. So when his friend invited him on the trip, he didn't let the flood stop him.

We thought we were going to die every single day for two weeks. We started wearing two life jackets. We couldn't drink all of our beer. We were so scary.

Honestly.

Normally, the Glen Canyon Dam at the top of the Grand Canyon

controls how much water runs downstream.

But in 83, the flood made things almost impossible to control.

Water filled the giant reservoir behind the dam, called Lake Powell, right to the brim.

To keep the water from spilling over, engineers frantically opened emergency outlet tunnels,

but the force of the flow began destroying the tunnels themselves.

Chunks of concrete, the size of buses flow began destroying the tunnels themselves. Chunks of concrete

the size of buses ripped free and sailed downstream. People were freaking out. At any moment,

the dam might break and open like a door, sending a massive wall of water all the way from Utah

to Mexico. They were using four by eight sheets of plywood on top of the dam to keep it from overtopping.

Sheets of plywood sitting on top of a 700-foot concrete dam.

That's the only thing that saved that dam.

Did you think that while you were on this trip, were you like, maybe the dam will break and will be caught in the monstrous blood?

Well, we talked about that a lot because, you know, it was imminent.

...