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)

A Xikrin woman holds her husband's shotgun while he cleans freshly hunted peccary in the river. According to tradition, Xikrin women are not allowed to leave the village while their husbands are out hunting a wife must patiently wait for his return. (Photo and caption by Taylor Weidman)

Anti-racist Loldiers of Odin clowns speak with police as they take to the streets against anti-immigration marchers in Tampere, Finland January 23, 2016. Police prevented the groups from confronting each other. On the northern fringes of Europe, Finland has little history of welcoming large numbers of refugees, unlike neighbouring Sweden. But as with other European countries, it is now struggling with a huge increase in asylum seekers and the authorities are wary of any anti-immigrant vigilantism. (Photo by Kalle Parkkinen/Reuters/Lehtikuva)

Germany's Angelique Kerber reacts after popping a bottle of champagne, a day following her win in the final match at the Australian Open tennis tournament, at the Government House in Melbourne, Australia, January 31, 2016. (Photo by Issei Kato/Reuters)

In this January 31, 2014 file photo released by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA), shows residents of the besieged Palestinian camp of Yarmouk, queuing to receive food supplies, in Damascus, Syria. That year, the U.N. was able to deliver food to about five percent of people in besieged areas including Yarmouk, while today estimates show the organization is reaching less than one percent. (Photo by UNRWA via AP Photo)

Indian dancers perform a fire breathing act during a procession to mark the 661st anniversary of the birth of Hindu guru Bawa Lal Dayal Maharaj in Amritsar on February 9, 2016. Bawa Lal Dayal Maharaj, a popular leader of his time, is especially revered by devotees of a temple in the town of Dhyanpur, some 45 kms north of Amritsar. (Photo by Narinder Nanu/AFP Photo)

Paramilitary policemen carry tyres as they take part in a training session in Zhangye, Gansu Province, China, March 1, 2016. (Photo by Reuters/Stringer)

An actress dressed as Wonder Woman walks between visitors during the season inauguration of the Madrid Warner amusement park in San Martin de Valdeiglesias, near Madrid, Spain, March 18, 2016. (Photo by Andrea Comas/Reuters)