BEIJING, Feb. 27 -- China on Friday vowed to improve the water quality of the Yangtze River as part of wider measures to balance economic activities and environmental protection along the world's third longest river.

In the years leading to 2020 China will work to ensure that over 75 percent of water in the Yangtze economic belt at least meets the Grade III standard, according to the National Development and Reform Commission (NDRC), the top economic planning agency.

China classifies water quality into six levels, from level I, which is suitable for drinking after minimal treatment, to level VI, which is severely contaminated.

The NDRC said China aims to make over 97 percent of the water from drinking water sources along the Yangtze belt Grade III before 2020.