This aerial photo taken on Aug. 21, 2023 shows the zigzag watercourse of the Yellow River in Tangke Township, Ruoergai County of Aba Tibetan-Qiang Autonomous Prefecture, southwest China's Sichuan Province. (Xinhua/Xing Guangli)

As the autumn breeze sets in, legions of succulent freshwater fish, once on the brink of extinction due to pollution, have reemerged in the Yellow River thanks to improvements in the water quality.

In 2022, the entire main course of the Yellow River, China's second-longest river, achieved a Class II water quality rating for the first time, a level that meets the hygienic standard for drinking water after conventional water purification treatment, according to data released by the Ministry of Ecology and Environment.

The environmental restoration efforts on the Yellow River are highly effective, said Fan Zhihui, head of the Yellow River basin ecological and environmental supervision and management bureau under the ministry.

Monitoring data indicates that in recent years, the proportion of good-quality water in the basin has increased by an average of over 5 percent per year.

However, the river was plagued by numerous problems for a long time.

Particularly in the late 1990s, pollution intensified, with the volume of pollutants entering the river far exceeding its environmental capacity. About 40 percent of the river's mainstream had water quality classified as "extremely poor." One-third of the original 16 aquatic species in the river became extinct.

"The unprecedented level of attention from the national and local governments, coupled with the most stringent environmental management efforts in history, have revitalized the once-ailing mother river," said Cai Zhiguo, an official with the bureau.

Each year, more than 15,000 swans flock to the Yellow River wetland in Sanmenxia City, central China's Henan Province, to spend the winter. The birds account for over 70 percent of the total population of wintering swans in China.

Following the improvement in the main stream water quality, work of restoring tributary flows will gain equal attention, said Fan.