Efforts taken to restore ecological environment in upper reaches of Yangtze River in Yunnan

File photo taken on Feb. 6, 2017 shows the Dian Lake in Kunming, southwest China's Yunnan Province. To keep Yangtze River clean and beautiful, efforts to restore ecological environment have been taken in the upper reaches of Yangtze River in Yunnan Province in recent years. (Xinhua/Lin Yiguang)