China has achieved robust economic growth and strengthened ecological conservation in the Yangtze River Economic Belt over the past decade, a senior official said.

The sections of water with fairly good quality in the belt increased from 67 percent in 2015 to 96.5 percent last year, while the regional GDP more than doubled during the same period, Wang Changlin, deputy head of the National Development and Reform Commission, said at a news conference organized by the State Council Information Office on Monday.

China has a five-tier quality system for surface water, with Grade I being the best. The water quality is considered fairly good if it reaches Grade III, which is suitable for most aquatic organisms.

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The belt's contribution to the country's GDP rose from 42.2 percent to 47.3 percent, Wang continued.

The news conference coincided with the 10th anniversary of a national conference presided over by President Xi Jinping in Chongqing on the development of the belt.

The Yangtze boasts a unique ecosystem, Xi stressed at the meeting held on Jan 5, 2016. To restore its ecology and environment will be an overwhelming task, and no large-scale development will be allowed along the river at present and for a long period to come, the president underscored.

The Yangtze River Economic Belt covers all but two of the 11 regions the river flows through, with Qinghai province and the Xizang autonomous region as exceptions. It also includes Zhejiang and Guizhou provinces, which are home to tributaries of the Yangtze.

Wang emphasized that since the 2016 conference, the principle of prioritizing well-coordinated environmental protection and avoiding excessive development has taken root in the belt, enhancing the ecological features of the Yangtze River.

Thanks to measures to control water pollution from industry, agriculture, and shipping, black and odorous water bodies have been essentially eradicated in prefecture-level cities along the Yangtze, he said.

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He further highlighted the dramatic water quality improvement in the Yangtze's main stream over the past decade. "The Yangtze's main stream has been transformed from having sections of Grade V water quality to maintaining Grade II standards throughout its entire course," he said.