The State Council decided on Wednesday to establish an experimental zone for ecological protection in Sanjiangyuan on the Qinghai-Tibet Plateau. The experimental zone, which covers 21 counties in four Tibetan autonomous prefectures as well as a township in Golmud in Qinghai province, is expected to explore a mechanism for the ecological development and environment protection, according to the State Council executive meeting presided by Premier Wen Jiabao. The Sanjiangyuan region, with an average altitude of more than 4,000 meters, is the source of three rivers - the Yangtze River, the Yellow River and the Lancang River. The green cover in the experimental zone is set to be increased by 15 to 20 percent by the end of 2015 and 25 to 30 percent by 2020, according to the draft of the experimental zone. The protection and restoration of the vegetations in the zone will be emphasized, and the balance between the grass fields and the number of livestock will be monitored and adjusted according to the ecological condition, said the draft. Construction of infrastructure in the zone will be strengthened with an eye on ecological protection to improve the life quality of the local people, according to the draft. The source lakes had experienced shrinking as a result of environmental damage caused by human activities and overgrazing by animals since late 20th century. Measures were taken to prevent soil erosion, artificially increase rainfall, forbid overgrazing and move herding families out of the region. About 50,000 people have been moved out in the past six years, according to official data. As a result, the lake area on the Qinghai-Tibet Plateau expanded in size by 245 square kilometers from 2005 to 2010.