Photo taken on June 20, 2012 shows colorful water mixed by mud water discharged from the Xiaolangdi Reservoir outlet and clean water vented from hydropower station in Mengjin County, central China's Henan Province. The Yellow River has been plagued by an increasing amount of mud and sand. Each year, the river bed rises as silt deposits build up, slowing the water flow in the lower reaches. The Xiaolangdi Reservoir in the middle reach of the Yellow River has experienced sand-washing operation for 13 times since 2002 and succeeded in clearing out the silt deposits at the dam and washing 762 million metric tons of mud and sand into the sea. The sand-washing operation of the Yellow River this year started on June 19 and will last for about 20 days. [Xinhua]