Egrets fly over the Yundang Lake in Xiamen, southeast China's Fujian Province, Sept. 9, 2020. Thanks to the continuous efforts of ecological protection, the Yundang Lake has been converted from a polluted lake to the landmark of the city. (Xinhua/Jiang Kehong)

Egrets forage near the Yundang Lake in Xiamen, southeast China's Fujian Province, Sept. 9, 2020. Thanks to the continuous efforts of ecological protection, the Yundang Lake has been converted from a polluted lake to the landmark of the city. (Xinhua/Jiang Kehong)

People walk around the Yundang Lake in Xiamen, southeast China's Fujian Province, Sept. 9, 2020. Thanks to the continuous efforts of ecological protection, the Yundang Lake has been converted from a polluted lake to the landmark of the city. (Xinhua/Jiang Kehong)

People walk on a lake-side passage around the Yundang Lake in Xiamen, southeast China's Fujian Province, Sept. 9, 2020. Thanks to the continuous efforts of ecological protection, the Yundang Lake has been converted from a polluted lake to the landmark of the city. (Xinhua/Jiang Kehong)

Aerial photo taken on Sept. 1, 2020 shows the view of Yundang Lake and its surroundings in Xiamen, southeast China's Fujian Province. Thanks to the continuous efforts of ecological protection, the Yundang Lake has been converted from a polluted lake to the landmark of the city. (Xinhua/Jiang Kehong)