Shine returns to SW China lake known as 'pearl in the plateau'
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In the heart of Weining Yi, Hui and Miao autonomous county, Bijie city, lies Caohai, the largest natural fresh water lake in Southwest China's Guizhou province.
With an elevation of more than two kilometers and home to more than 200 kinds of birds, including the endangered black-necked crane, the 25 square kilometer lake is called by some "a pearl in the plateau".
The "pearl" hasn't always shined. It once shrank to only five square kilometers due to reclamation. After gaining its current size, it was threatened by unrestrained tourism and untreated domestic sewage.
Things have improved since 2015, when the county started a campaign to repair Caohai's environment.
According to local officials, the county has paid local farmers to collect 40 square kilometers of water, wetland and farmland to carry out protection projects, including wetland restoration and building foraging habitats for birds.
Also, the county banned tourism in the lake in a statement issued in 2019.
Xia Chaowen, an official of the management committee of the Caohai National Nature Reserve, which covers 120 square kilometers, said visitors used to take farmers' boats to tour the lake, risking littering, alarming birds and damaging aquatics.
Chemical fertilizers and pesticides used by the farmers posed another hazard to the water, Xia said.
The county also has moved more than 2,300 households away from the shores of the lake.
Located next to the county's traditional communities, Caohai can be easily affected by human activities. Before the overhaul campaign started in 2015, residents living around the lake used to discharge sewage directly into the water.
As a result, the county built a sewage treatment plant on the upper stream of Caohai, processing 8,000 tons of sewage every day on average, as well as 19 smaller ones around the lake.
Hong Huining, deputy head of the major treatment plant, showed visitors how sewage is treated in her factory during an interview in June.
The wastewater becomes clear and odorless after a number of steps to remove impurities. In the end, it runs through an artificial wetland filled with different kinds of plants used to further deposit and absorb harmful ingredients before discharge into Caohai.
Positive outcomes occurred after five years of restoration efforts.
Li Zhenji, an official with the Environment Monitoring Department under the Caohai Reserve Management Committee, said 246 types of birds were recorded in the region this year, 18 more than in 2010.
The overhaul campaign has improved biological diversity in Caohai, leading to a more stable and stronger biological system, Li said.
Plants such as the water fern, which used to "grow wildly" over Caohai due to deteriorated water quality and disruption in the growth of aquatics underneath, can hardly be seen in the lake now, while other plants rarely seen in the past became more common in recent years, Li said.
Caohai is part of the Yangtze River system. It is the source of the Luoze River. The river flows into the Hengjiang River, which is a branch of the Jinsha River.
As a result, protecting Caohai is not only important for Guizhou, but also relates to the environment of neighboring Yunnan and Sichuan provinces, Li said.
Hong, who works in the sewage treatment factory, recalled that the water in Caohai worsened in the 1990s, and she was "very disappointed" to see the lake turn "black and smelly".
With the water quality improved significantly since 2015, Hong said now she and her husband often take a walk by the lake to enjoy its "pleasant view", especially the "good air and clear water" in summer.
Hong said she is confident that Caohai will keep improving for the better, adding that the lake is worth protection by every local person.
文字：王青云
图片：王瑾、瞿宏伦
视频：高航
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