The water in Taihu Lake, the country's third-largest freshwater lake in the lower Yangtze River region, has been designated as fairly good quality for the first time in the past 30 years, according to the department of ecology and environment of Jiangsu province.

Monitoring showed that the quality of the water in the lake stood at Grade III in 2024, the department said in a news release on Sunday.

China has a five-tier quality system for surface water, with Grade I the best. Water with a quality of Grade III is considered fairly good and is suitable for most aquatic organisms to live in.

Located in the highly developed Yangtze River Delta, Taihu became increasingly polluted due to industrialization and urbanization in the region after China began its reform and opening-up efforts in the late 1970s.

According to the 2012 Health Status Report of Taihu Lake, which was compiled by the Taihu Basin Authority of the Ministry of Water Resources, seven of the 22 major rivers that empty into Taihu had water quality below Grade V.

Treatment for large, shallow lakes like Taihu is a global challenge, as sediment on their bottoms can be easily stirred up even by a slight breeze, causing nutrient pollution that features the dispersal of nitrogen and phosphorus.

The significant environmental improvement in Taihu happened thanks to persistent efforts from Jiangsu authorities to ramp up pollution control.

Since 2007, Jiangsu has invested over 300 billion yuan ($41 billion) into Taihu treatment, with pollution source management and pollutant interception as key priorities, according to Jiangsu authorities.

Last year, almost 6.4 million cubic meters of mud were dredged from the lake, and more than 1.7 million metric tons of blue-green algae were cleared.

Jiangsu also rolled out a series of measures to remediate Taihu's ecosystem. In a pilot program, for instance, more than 190 hectares of submerged plants have been planted in eastern and northern parts of the lake. In the western part of Taihu, almost 67 hectares of reed have been restored.

With 191 zones for wetland protection established, the decreasing trend in Taihu's wetland area has been fundamentally reversed, according to Jiangsu authorities.

After more than a decade of comprehensive and systematic governance, the water quality of Taihu has improved each year, not only without hindering economic development but also while driving industrial upgrading.

Suzhou, Wuxi and Changzhou, the three major cities on the shores of Taihu, have seen tertiary industries become the largest part of their industrial structures since 2014, surpassing secondary industries. In 2023, the contributions of high-tech industries to the total value added of industrial enterprises above the designated size reached 53 percent in Suzhou, 51.8 percent in Wuxi and 56 percent in Changzhou.

"The treatment practices in Taihu fully demonstrate that as long as the determination is made and the right path is found, large, shallow lakes can also be effectively managed," said Jiang Wei, head of department of ecology and environment of Jiangsu province.

Xinhua contributed to this story.

houliqiang@chinadaily.com.cn