Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

A female hippopotamus named “Mali”, which means Jasmine, eats fruits arranged to look like a cake during her 50th birthday celebration at Dusit Zoo in Bangkok, Thailand September 23, 2016. (Photo by Chaiwat Subprasom/Reuters)

A street performer jumps in the air inside Central Park as the colors of autumn become more prevalent in New York, October 29, 2015. (Photo by Lucas Jackson/Reuters)

Men carry others, so they do not soil their shoes and clothes, through a mudslide caused by Tropical Storm Erika in Carries, Haiti, August 29, 2015. Erika, a tropical storm that killed 20 people on the Caribbean island of Dominica and at least one person in Haiti, fell apart on Saturday over eastern Cuba, the U.S. National Hurricane Center said. (Photo by Andres Martinez Casares/Reuters)

The cast of Pose (L-R) Indya Moore, Hailie Sahar, Michaela Jaé Rodriguez, Angelica Ross, and Dominique Jackson speak onstage during the 27th Annual Critics Choice Awards at Fairmont Century Plaza on March 13, 2022 in Los Angeles, California. (Photo by Frazer Harrison/Getty Images)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

An Israeli tank moves into position in the Israeli controlled Golan Heights during fighting between forces loyal to Syrian President Bashar Assad and rebels in the Druze village of Khader in Syria, Tuesday, June 16, 2015. As many as 20 members of the Druze minority sect were killed last week, the deadliest violence against the Druze since Syria's conflict started in March 2011, sparking fears of a massacre against the sect. (AP Photo/Ariel Schalit)