Aerial photo taken on Aug. 4, 2020 shows an ecological buffer zone in Siping City, northeast China's Jilin Province. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)

Aerial photo taken on Aug. 4, 2020 shows a wastewater treatment plant in Siping City, northeast China's Jilin Province. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)

A resident takes a walk at the Siping West Lake wetland park in Siping City, northeast China's Jilin Province, on Aug. 4, 2020. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)

A staff member checks facilities at a wastewater treatment plant in Siping City, northeast China's Jilin Province, on Aug. 4, 2020. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)

Aerial photo taken on Aug. 4, 2020 shows an outfall of a wastewater treatment plant in Siping City, northeast China's Jilin Province. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)

Aerial photo taken on Aug. 4, 2020 shows a wastewater treatment plant and the Siping West Lake wetland park in Siping City, northeast China's Jilin Province. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)

Aerial photo taken on Aug. 4, 2020 shows a wastewater treatment plant in Siping City, northeast China's Jilin Province. Located at the upper reaches of the Liaohe River, Siping has launched a series of projects to improve the ecological environment and water quality in the river's basin. (Xinhua/Zhang Nan)