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 girl plays with coloured chicks for sale prior to Easter celebrations in Byblos, Lebanon on March 22, 2015. (Photo by Jamal Saidi/Reuters)

Hundreds of Nigerians celebrate at an intersection in the flashpoint northern city of Kaduna on March 31, 2015 the victory of main opposition All Progressives Congress (APC) presidential candidate Mohammadu Buhari. (Photo by Nichole Sobecki/AFP Photo)

In this photo released by Xhinhua News Agency, a rescuer evacuates residents near the site of a chemical plant blast in Zhangzhou, southeast China's Fujian Province Tuesday, April 7, 2015. Six people have been hospitalized and hundreds of firefighters deployed to battle a blaze sparked by an explosion at Goure PX Plant that produces the toxic chemical paraxylene, officials said Tuesday. (Photo by Wei Peiquan/AP Photo/Xinhua)

A police officer has weapons blessed by a Hindu priest during the Vishwakarma Puja festival in the outskirts of Agartala, India, September 17, 2016. (Photo by Jayanta Dey/Reuters)

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)

Kendall Jenner and Kylie Jenner seen in this celebrity social media picture on September 1, 2016. (Photo by XposurePhotos.com)

Hindu women apply “sindhur”, or vermillion powder, on the face of a woman after worshipping the idol of the Hindu goddess Durga on the last day of the Durga Puja festival in Chandigarh, India October 11, 2016. (Photo by Ajay Verma/Reuters)