* Taihu, China’s third-largest freshwater lake, has seen its water quality improve to its best level in 30 years.
* The lake’s water quality has improved from Grade V — the lowest level in China’s five-tier water quality rating system — to Grade III, which means it is now classed as “fairly good.”
* Strict environmental measures did not hinder economic development in the region, but spurred industrial transformation through scientific and efficient management.
NANJING, March 13 (Xinhua) — Taihu, China’s third-largest freshwater lake, lies in the country’s manufacturing heartland and has seen its water quality improve to its best level in 30 years, once again demonstrating China’s resolve to protect ecology as it pursues economic and social development.
Since 2007, the population of the Taihu Lake basin has increased by nearly 7 million, the region’s total economic output has expanded 3.6-fold. It now accounts for 10 percent of China’s total GDP. Meanwhile, the lake’s water quality has improved from Grade V — the lowest level in China’s five-tier water quality rating system — to Grade III, which means it is now classed as “fairly good.”
Restoring large lakes that suffer from eutrophication is a global challenge, but the experience of Taihu has proved that it is possible.
CLEANING LAKE WATER
Taihu, which spans 2,338 square kilometers, is located in the Yangtze River Delta region, one of China’s most industrialized and densely populated areas. As an important water source for 17 million people in east China, it has a history of pollution, most notably since the 1990s due to rapid industrialization and urbanization in the region.
In May 2007, a severe outbreak of blue-green algae in the waters of Wuxi City in Jiangsu Province disrupted the drinking water supply for over 1 million residents, earning Taihu the grim reputation of being the region’s “sewage sink.”
Shinichiro Matsuzaki, a researcher at Japan’s National Institute for Environmental Studies, said that Taihu’s ecosystem had been trapped in a “vicious cycle of decline.” What he did not expect, however, was how swiftly China not only halted further deterioration but also set the lake on the fast track to recovery.
One of the most critical steps to reducing internal pollution is large-scale dredging. Over the past two decades, approximately 55 million cubic meters of silt have been removed from Taihu Lake through various methods.
Taihu Star, an intelligent dredging vessel, was put into operation in March 2024. It uses advanced spiral cutter technology to extract and separate sediment, processing up to 5,000 cubic meters daily.
Jiangsu has been implementing a package of pollution control measures since 2007, putting pressure on phosphorus-related enterprises near the lake to reduce discharge, and promoting the collection and treatment of wastewater, among other measures. It has shut down or restructured nearly 60,000 pollutive factories.
To manage wastewater resulting from its growing population, the government has built 32,000 kilometers of sewage pipelines, equivalent to 80 percent of Earth’s equatorial circumference. This extensive infrastructure has significantly reduced the amount of household pollution that enters the lake.
Additionally, large-scale wetland restoration projects have strengthened the lake’s natural resilience. More than 30 ecological buffer zones and 190 wetland conservation areas have been established.
In September 2024, Jiangsu’s Department of Ecology and Environment launched an intelligent online platform, which monitors the water quality of Taihu Lake using automated monitoring data from over 400 locations, as well as information from more than 40,000 pollution sources.
With satellite imagery streaming in real-time, drones deployed on scheduled checks and artificial intelligence assigning tasks, the platform provides critical support for algae bloom monitoring, pollution source tracing, the issuance of water quality alerts, and ecological compensation mechanisms.
Last summer, the average area of the lake’s blue-green algae bloom dropped 15.8 percent year on year, and the average density dropped 17.5 percent, according to the department.
UPGRADED INDUSTRIES
Strict environmental measures did not hinder economic development in the region, but spurred industrial transformation through scientific and efficient management.
In 2024, high-tech industries accounted for over half of the total output of industrial firms above the designated size in three major cities of Jiangsu: Suzhou, Wuxi and Changzhou. Suzhou’s biopharmaceutical sector exceeded 240 billion yuan (about 33.46 billion U.S. dollars), Wuxi’s semiconductor industry contributed more than 10 percent of national production, and Changzhou emerged as a major hub for new energy industries.
“The Taihu experience demonstrates that with the right policies and firm commitment, even large, shallow lakes can be effectively restored, and economic development and ecological protection can reinforce each other,” said Jiang Wei, director of Jiangsu’s Department of Ecology and Environment.
“Taihu Lake stands out as a benchmark for large-scale eutrophic lake restoration,” said Zhu Guangwei, a researcher at the Chinese Academy of Sciences’ Nanjing Institute of Geography and Limnology. “Its transition from a ‘green soup’ to clear waters is an extraordinary achievement that brings invaluable lessons for the world.” ■
（Video reporters: Lin Kai, Liu Yuxuan; Video editors: Zhang Yucheng, Roger Lott, Zhao Xiaoqing）
