Lakeside farms

A worker removes garbage from the lake.SONG RONGCHENG FOR CHINA DAILY

In addition to problems caused by industry, livestock and poultry farms along the lakeside are also significant sources of pollution.

According to Zhang, the annual waste from the farms equals that of 6.4 million pigs, and as one pig daily produces seven times more waste than a human being, the sewage discharged into the lake annually is equal to that generated by more than 40 million people.

When the office investigated 15 rivers that feed the lake last year, it discovered 114 illegal livestock farms along their banks; only 12 had been fitted with facilities for treating sewage, and only nine of them functioned well.

However, local governments say they can't close the farms because they are unable to compensate the farmers for their losses. Last year, the Yixing government paid more than 100 million yuan to close farms around just one river.

"We understand that the farmers need to run the farms to support their families," said Wang Yunxian, director of the Changzhou branch of the general office. "We also understand that local governments will come under great financial pressure if they close the farms, so sometimes we feel that successful pollution control is extremely hard to achieve."

Zhu said short-term economic considerations often outweigh long-term ambitions: "The provincial government ordered that 10 to 20 percent of increased annual revenue must be allocated to treat water pollution in the lake, but some local governments are reluctant to follow orders, let alone close businesses and farms. They complain that closing the businesses would affect local economic development, and they refuse to launch more treatment projects."

According to a 2013 survey conducted by the Chinese Academy of Sciences, the level of nitrogen in wastewater discharged into the lake was 3.3 times higher than national standards, and phosphorus levels were 2.5 times the standard.

"The eutrophication of the waters of the lake will continue for a long time, as will the outbreaks of algae," Zhang said. "We can never be too careful about controlling water pollution in the lake, and we must make great efforts to make it work."

Contact the writer at cangwei@chinadaily.com.cn