Hydropower, shunned just a few years ago as an environmental scourge, is experiencing a remarkable resurgence in the U.S. Dams are still viewed warily; in fact, Congress is considering dismantling four hydroelectric dams blamed for depleting salmon in the Klamath River basin in southern Oregon and northern California.
But engineers and entrepreneurs are pressing an alternative view of hydropower that doesn't involve new dams. They argue that plenty of efficient, economical energy can be wrung from other water resources, including ocean waves, free-flowing rivers, irrigation ditches—even the effluent discharged from wastewater treatment facilities.