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 view of the construction site of the Chateau de Guedelon near Treigny in the Burgundy region of France, September 13, 2016. Blacksmiths, stonemasons and quarry men are hard at work in a Burgundy forest building a 13th-century-style castle using the most basic tools and materials, replicating the methods used hundreds of years ago to better understand them. (Photo by Jacky Naegelen/Reuters)

Garbage, including plastic waste, is seen at the beach of Costa del Este, in Panama City, on April 19, 2021. Every two weeks, Marine Biology students descend about five meters in the sea to take care of a coral nursery of the staghorn species (Acropora cervicornis) in Portobelo, Panama, with which they aim to restore reefs damaged by climate change and pollution, as part of the Reef2Reef project. (Photo by Luis Acosta/AFP Photo)

A military helicopter flies over people during the Afghan Security Forces Exhibition, at the Darul Aman Palace in Kabul, Afghanistan, Wednesday, March 3, 2021. The three-day military exhibition in Kabul allowed civilians to have a first hand view and take pictures of weaponry used by Afghan Security forces. (Photo by Rahmat Gul/AP Photo)

Visitors to a mall grasp at air as they try out an augmented reality experience of a digital art gala in Beijing, Tuesday, May 2, 2023. (Photo by Ng Han Guan/AP Photo)

The top layer of muskeg and earth (L) is removed at the Syncrude tar sands operations near Fort McMurray, Alberta, September 17, 2014. Syncrude currently produces 350,000 barrels per day of high quality light, low sulphur crude oil according to company reports. (Photo by Todd Korol/Reuters)

Carlos Martinez (L), a representative of the Guinness World Records, examines the cooking process of a chocolate coin during an attempt to break the Guinness World Record for the biggest chocolate coin in Caracas, Venezuela, October 1, 2015. More than 80 people will work with 100% Venezuelan cacao to create the coin that is estimated to weigh 1,000 kg, according to local media. (Photo by Carlos Garcia Rawlins/Reuters)

A woman poses next to two mailboxes along a street in Taipei on August 11, 2015 that were reportedly bent by strong winds brought by Typhoon Soudelor over the weekend. The two iron mailboxes have become an unlikely attraction, drawing thousands of snap-happy visitors and have even become a backdrop to a wedding photo shoot. The typhoon, which hit in the early hours of August 8 and was billed as the most powerful typhoon this year, uprooted trees, brought down electricity poles, knocking out power to a record 4.3 million households, while leaving eight dead and four missing. (Photo by Benjamin Yeh/AFP Photo)