Modern River Engineering

Humans have reshaped nearly every major river. China's Three Gorges Dam on the Yangtze is one of the world's largest power stations, but its reservoir displaced over a million people and submerged whole towns. The Colorado is so heavily diverted that it often no longer reaches the sea, supplying water to tens of millions of people and vast farmland. Yet dam removal is gaining momentum: taking down the Elwha Dam let salmon return after a century, and the ecosystem recovered faster than expected.