XINING - A sprawling lake area on the Qinghai-Tibet Plateau that serves as the source of China's three major rivers has expanded after the government intervened six years ago to curb its shrinking due to deteriorating ecology.

The lake area of Sanjiangyuan, which literally means the source of three rivers, in northwest Qinghai Province grew by 245 square kilometers over the past few years, Li Xiaonan, deputy director of the Sanjiangyuan Ecological Preservation and Construction Office, said Tuesday.

In particular, the twin lakes that supply 49 percent of the headwaters of the Yellow River, which runs 5,460 kilometers across the country into the Bohai Sea near the Pacific, expanded by 166 square kilometers from its all-time low of 1,071 square kilometers in 2003.

Back then, the water levels were so low that the headwaters of the Yellow River briefly dried up.

Sanjiangyuan also supplies the headwaters of two other major rivers -- the Yangtze River and the Lancang River, which is called Mekong in southeast Asia. But the source lakes had been shrinking due to the deteriorating ecosystem that the government blamed on rising human activities and overgrazing.

Over fears that the shrinking of the source lakes might eventually dry up the mighty Yellow River, the central government initiated a 7.5 billion yuan ($1.12 billion) project in 2005 to repair the ecological system of Sanjiangyuan by treating soil erosion, increasing man-made rainfall, banning overgrazing, and resettling the herding families out of the region.

About 50,000 people, mostly ethnic Tibetans, of about 10,000 herding families have been moved out over the past six years while rain-making rockets increased the region's precipitation by 31 billion cubic meters, according to Li and Zhou Bingrong, senior engineer of the provincial meteorology research institute.

Li said since efforts began in 2005 to repair the fragile plateau wetland, the Sanjiangyuan lake area is now able to hold more water, and the quality of the water has improved.