Hydropower comes in many forms, though most people still associate it with big dams. In the heyday of dam building, projects like Grand Coulee Dam and Boulder Dam in the American West were monumental efforts. These were some of the most ambitious and costly construction projects ever undertaken. Back then, we didn't fully understand how dams could disrupt ecosystems—blocking fish passage, altering sediment flow, and changing entire river systems. But now we do, and as a result, large dams have fallen out of favor in many places. And where the U.S. was once the leader in large scale hydropower, we're now removing more dams than we're building. Today, the biggest obstacles to constructing new hydroelectric projects in the U.S. aren't just environmental—they're economic and regulatory. Escalating construction costs and complex permitting processes have significantly slowed the pace of development. But hydropower is a very site-specific technology—and there are plenty of ways to make it more environmentally friendly. In Alaska, for example, we have dozens of what are called "run-of-river" hydro systems. These projects harness the natural flow of water to generate electricity, often without the need for large dams or reservoirs—and without blocking fish passage, which is a big deal in a state where salmon are central to both ecosystems and communities. Closing the Gap is hosted by Gwen Holdmann and edited by Jennifer Pemberton. This episode was produced by Tony Williams. Music is from Blue Dot Sessions.

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