Gulls on an islet in the middle of the Hongjiannao Lake. [Photo provided to China Daily]

In order to protect the lake, Shenmu county established a nature reserve around it in 2003. Since 2006, 617 million yuan ($92.5 million) has been spent on preserving the lake — 596 million yuan of which came from the central government — but the downward trend has not been halted.

Dang Yabo, office director of the nature reserve, believes there is a shortage of water coming into the lake.

Its two main sources — the Yingpan and Manggaitu rivers in Inner Mongolia — were dammed between 2005 and 2009. Dang estimates that reservoir construction has decreased the amount of water flowing into Hongjiannao by 60 percent annually.

To make things worse, three of the four rivers in Shaanxi province that used to supply the lake with water dried up 10 years ago, Dang said.

Experts including Zhang Zhenwen, director of Shaanxi Provincial Academy of Environmental Sciences, and Hou Guangcai, deputy chief engineer of China Geological Survey's Xi'an Research Center, have also warned that mining activities near the lake, which are reportedly being considered by the Inner Mongolia government, could change its ecological system entirely.

"Assessment of mining's influence must be conducted by a joint team including experts and the governments of both Shaanxi and Inner Mongolia," they suggested in a written statement.

The Shenmu county government also suggested that the current county-level nature reserve be elevated to a national-level one, which would involve relocating 60,000 people living near the lake, and increasing artificial precipitation in the area.