For decades, dams represented human ingenuity at its finest. Giant walls of earth and concrete that could tame rivers, generate electricity, and irrigate crops. Yet, while some countries like China are forging ahead with ambitious dam-building plans, a growing movement in Europe and the United States is challenging whether these structures still make sense.  The most dramatic example of this shift is the dismantling of four dams on the Klamath River, which flows through Northern California and southern Oregon. The $500 million removal project, the largest of its kind in the United States, was driven by concerns over environmental impact, costly upgrades required by modern regulations, and the longstanding need to restore salmon populations that had been blocked for a century.

Other Klamath River news:

• Letters About Water: Video: A chosen life: Klamath people restoring the earth