Workers clean up rubbish on Dianchi Lake in Kunming, Southwest China's Yunnan province. [Photo/Xinhua]

Ding Zhongli, chairman of the Central Committee of the China Democratic League, has called for more support to Yunnan province to further improve its environment.

Ding, an academician at the Chinese Academy of Science, made the remarks in a news conference on Sunday.

Held on the sidelines of the first session of the 14th National Committee of the Chinese People's Political Consultative Conference in Beijing, the conference was also attended by leaders from other non-Communist parties and the All-China Federation of Industry and Commerce.

The China Democratic League, together with the other seven non-Communist parties, started a program to supervise environmental protection work in the basin of the Yangtze River, Asia's longest, about two years ago, he said. The league designated Yunnan as its target.

Considering the comparatively poor technology capacity in Yunnan, the league organized some of its members who are environment experts and other academicians to help the province conserve the Yangtze, he said.

He said the team found some major challenges that have been hindering water pollution control work in the province.

Although the government has invested a lot to treat Dianchi Lake in Kunming, Yunnan's capital, the quality of water in the lake has remained at Grade IV, in some cases even worse, he said.

China has a six-tier quality system for surface water, with Grade I the best.

The aging sewage pipe network is to blame for the situation, he said. Sewage leakage is prone to occur in these aging facilities which then contaminates Dianchi.

As a key region for phosphorus mining, Yunnan is also plagued by pollution caused by ardealite, a solid waste matter generated in phosphorus production. Some of the waste is piled up near the Yangtze. "The disposal of ardealite is a hard nut to crack for the province," he said.

Due to its limited land resources, agriculture development in Yunnan is highly intensive, which means more pollutants are discharged from the sector, he continued.

"As Premier Li Keqiang said in the government work report, we still have a long way to go in protecting the environment," Ding said. "Yunnan still needs support and more government investment to help it address these problems."