The Bahe River, a tributary of the Yellow River, stretches over 100 kilometers, with a significant portion flowing through the urban area of Xi'an City, in northwest China's Shaanxi Province. It provides vital ecological and drinking water resources for the region.

However, the river, next to which the Olympic Sports Center hosted the 14th National Games and which serves as a public spot for various activities, was once stinky and heavily polluted due to the uncontrolled discharge of household sewage a few years ago.

"A large volume of polluted water flowed down the river, resulting in bad water quality, a foul smell, and the death of zooplankton in the river. Every year, during summer, in August, the river experienced increased pollution and eutrophication due to reduced water," said Feng Chuangmin, who was involved in the water quality improvement project for the river.

Since 2018, the city has enacted comprehensive measures to combat pollution, including adjusting the river's curvature, installing reinforced slope protection, and implementing ecological facilities like floating islands and emergent plants. Additionally, a project has been initiated to implement sewage interception and management measures along the river. Renovation of all sewage treatment plants along the river has occurred, with concerted efforts directed at enhancing water quality and the ecological environment throughout the entire river basin.

According to Feng, the water quality of the Bahe River has undergone significant improvement, consistently maintaining a classification above Grade III since 2021, which represents the third-highest level in the country's five-tier water quality system.