John Wesley Powell lost his right arm to a bullet at the Battle of Shiloh in 1862. The surgeons amputated it below the elbow. He went back to the war anyway and fought at Vicksburg. Seven years later, he decided to do something nobody had ever done: take boats down the Green and Colorado Rivers, straight through the Grand Canyon. At the time, that stretch was literally a blank spot on the map. Some people believed the river disappeared underground or plunged over giant waterfalls. In May 1869, Powell set off from Wyoming with nine men and four wooden boats. Most of them had zero whitewater experience. Two weeks in, one of the boats smashed apart on the rocks and took a huge chunk of their food and gear with it. They named the spot Disaster Falls. One man had seen enough and walked out a few weeks later. At one point Powell was scaling a cliff and got stuck on a ledge, hanging on with his only hand, unable to go up or down. One of his men climbed above him, took off his long underwear, and lowered it down so Powell could grab on and be pulled to safety. By August they were deep inside the Grand Canyon. The flour was moldy. They were living on bad bread, dried apples, and coffee. Their clothes were rags. The rapids kept getting worse, and nobody knew how much canyon was left. Then they reached a rapid so violent that three men said they were done. They would climb out of the canyon and walk to the nearest settlement instead. Powell couldn't talk them out of it. The two groups shook hands, the three men took a rifle and some letters to mail home, and climbed up the canyon wall. Powell and the others ran the rapid and made it through. The very next day, they floated out of the Grand Canyon. The three men who climbed out were never seen again. Powell went on to run the U.S. Geological Survey and spent years warning Congress that the West didn't have enough water to support the kind of growth everyone was planning. They ignored him. Today the second largest reservoir in the country is named after him. Lake Powell. A man who warned about water shortages, now best known for a lake that's been shrinking for decades.