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)

North Koreans wave as Hughes MD-500 helicopters fly past during an aerial display on Saturday, September 24, 2016, in Wonsan, North Korea. North Korea on Saturday opened an air festival featuring sky diving, demonstrations by its air force and lots of beer to promote a newly renovated and upgraded commercial airport in the coastal city of Wonsan that it hopes will draw for foreign tourists. (Photo by Wong Maye-E/AP Photo)

Debris fly into the air as foreign fishing boats are blown up by Indonesian Navy off Batam Island, Indonesia, Monday, February 22, 2016. Authorities on Monday sank dozens of fishing boats caught operating illegally in Indonesian waters as part of the country's campaign to battle illegal fishing. (Photo by M. Urip/AP Photo)

A participant in wingsuit flies above Tianmen Mountain at Zhangjiajie Scenic Spot during the 4th Red Bull WWL China Grand Prix on October 16, 2015 in Zhangjiajie, Hunan Province of China. The 4th Red Bull WWL China Grand Prix will last three days from October 16-18 in Zhangjiajie. (Photo by ChinaFotoPress/Getty Images)

“The Victoria Falls or Mosi-oa-Tunya is a waterfall located in southern Africa on the Zambezi River between the countries of Zambia and Zimbabwe. A famous feature is a naturally formed pool known as the Devil's Pool, near the edge of the falls, accessed via Livingstone Island in Zambia. When the river flow is at a certain level, usually during the months of September to December, a rock barrier forms a pool with little current; some people swim in the pool. Occasional deaths have been reported when people slip over the edge of the rock barrier”. – Wikipedia

Photo: Devil's Pool – Victoria Falls, Zambia. (Photo by Siena College Study Abroad)

A fireman from the London Fire Brigade, wearing a smoke helmet. (Photo by Topical Press Agency/Getty Images). Circa 1908

American actor and politician Ronald Reagan stands behind his wife, actor Jane Wyman, who sits down to dinner, circa 1940s. She is seated between two unidentified men, both in military uniforms adorned with Arms Qualification medals, the man on the right with Sharpshooter and Marksman badges and the man on the left, a Captain, with Expert and Sharpshooter badges. Reagan wears a military uniform with Cavalry branch insignia and Wyman wears a black dress with stranded pearl necklace, and a black hat with a veil. (Photo by Hulton Archive/Getty Images)

People play "Palin", a traditional ritual and ancestral Mapuche game played with curved sticks called "Chuecas" and a wooden ball, during a meet on Dia de la Raza (Day of the Races), also known as Columbus Day in Vina del Mar, Chile October 11, 2015. (Photo by Rodrigo Garrido/Reuters)