XINING - The air and water quality in the headwaters area of China's three most vital rivers is excellent, according to the latest monitoring.

The water quality of the upper trunk streams and main tributaries of the Yangtze, Yellow and Lancang rivers were all level II or above, according to a five-year monitoring report released by the environmental protection bureau of Qinghai province on Friday.

Lancang river is known as Mekong when running through Myanmar, Laos, Thailand, Cambodia and Vietnam.

Fresh water quality above level II in China means the water is drinkable without being treated.

The conclusion was based on the results from 40 monitoring sections between 2011 and 2015, according to the provincial environmental protection bureau.

The results also indicate that China's ecosystem protection project, which was launched in 2005, is effective.

The three major rivers are essential to Chinese and Asian aquatic ecosystems. Their headwaters are also most vulnerable to global climate change.