Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)

A seagull flies through a rainbow near the Savannah River and the open spillway at Thurmond Dam in Clarks Hill, SC, Monday, January 4, 2016. (Photo by Michael Holahan/Augusta Chronicle via AP Photo)

A man walks inside the flooded Cochin international airport after the opening of Idamalayar, Cheruthoni and Mullaperiyar dam shutters following heavy rain, on the outskirts of Kochi, India, August 15, 2018. (Photo by Sivaram V/Reuters)

Tourists are watching the sunrise from a viewing platform on the Three Gorges Dam in Yichang, China, on June 23, 2024. (Photo by Costfoto/NurPhoto/Rex Features/Shutterstock)

Fearless daredevils clamber up the worlds highest man-made climbing wall – running up the face of a 540ft dam. The Diga di Luzzone in Switzerland is considered by climbers as the Everest of wall climbing. (Photo by Ilana Marcus/Caters News)

A woman dressed as “The Milkmaid” (Het Melkmeisje), after a painting by Dutch painter Johannes Vermeer, picks up tulips at the National Tulip Day on the Dam, Amsterdam, the Netherlands, 16 January 2016. The event is the official start of the international tulip season which runs until the end of April. (Photo by Evert Elzinga/EPA)

Residents cross a swelling dam, due to rising waters brought about by Typhoon Koppu, in Las Pinas city, metro Manila October 19, 2015. Powerful typhoon Koppu ploughed into the northeastern Philippines before dawn on Sunday destroying homes and displacing 10,000 people and whipping up coastal surges four meters (12 feet) high, disaster agency officials said. (Photo by Ezra Acayan/Reuters)

Men look on from the banks of Rio Doce (Doce River), which was flooded with mud after a dam owned by Vale SA and BHP Billiton Ltd burst, as the river joins the sea on the coast of Espirito Santo in Regencia Village, Brazil, November 22, 2015. (Photo by Ricardo Moraes/Reuters)