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)

Four-year-old Solaris Arias (right) jumps through water spraying from an open fire hydrant in Providence, Rhode Island, on June 20, 2012. Much of the state remained under a heat advisory Tuesday afternoon because of the steamy air mass that has moved into the region resulting in temperatures in the 90s. (Photo by Steven Senne/AP Photo)

A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Connecticut. A man killed his mother at their home and then opened fire inside the elementary school where she taught, massacring 26 people, including 20 children, as youngsters cowered in fear to the sound of gunshots reverberating through the building and screams echoing over the intercom. (Photo by Jessica Hill/Associated Press)

A man is seen wrapped with pythons, some which include the Albino Burmese Python, as part of a show celebrating the coming Year of the Snake in the Chinese calendar, while spectators look on, in Malabon city, north of Manila, Philippines, December 28, 2012. (Photo by Romeo Ranoco/Reuters)

Afghan air force 2nd Lt. Niloofar Rhmani walks the flight line at Shindand Air Base, Afghanistan, prior to her graduation from undergraduate pilot training, on May 13, 2013. Rhmani made history on May 14, when she became the first female to successfully complete undergraduate pilot training and earn the status of pilot in more than 30 years. She will continue her service as she joins the Kabul Air Wing as a Cessna 208 pilot. (Photo by Senior Airman Scott Saldukas/USAF)

French fashion model Christiane Richard wears a bikini while drinking her morning coffee, 1950. (Photo by Nat Farbman/Time & Life Pictures/Getty Images)

These girls are scantily dressed as they head out for a night out in Portsmouth, Hampshire on September 21, 2016 in matching outfits. Thousands of Portsmouth University students enjoy freshers week. Teenagers enjoy their first taste of freedom in bars and clubs near Portsmouth Guildhall which on a midweek alcohol fuelled night of fun in the early hours of Wednesday morning much to the despair of local residents who get disturbed up to 4am when they eventually wander home. Girls dressed in “Dirty Disco” outfits with “Don't tell daddy” on their bums. (Photo by Paul Jacobs/PictureExclusive.com)

People walk near a collapsed mosque following an earthquake in Meuredu, Pidie Jaya in the northern province of Aceh, Indonesia December 7, 2016. (Photo by Irwansyah Putra/Reuters/Antara Foto)