Hydroelectric dams generate 6 percent of the United States’ electricity. But while hydropower is considered the country’s largest source of renewable energy, dams can have immense environmental impacts. In a new study published in Nature Sustainability, researchers show that solar panels could produce the same energy as all the dams in the U.S. while taking up only 13 percent of the square footage.

Dams can degrade river ecosystems, obstruct fish migration, affect water quality and negatively impact areas around the reservoirs. Plus, many of the hydroelectric dams in the U.S. are ageing so they have safety risks and will require expensive maintenance. These issues have led to a growing dam-removal movement around the country.