Jinan -- Lock gates were opened on Friday in eastern China to send water from the Yellow River to the largest freshwater lake in the northern part of the country, Baiyangdian.
The lake has been stricken by continuous drought and has to give up its nearest water sources to back up Beijing's water use for the upcoming Olympics.
Water began to run out of the Huanghan Lock Gate in Liaocheng City, Shandong Province, at 70 cubic meters per second. It will take an estimated 120 days to feed 150 million cubic meters through a 400-kilometer diversion route to Baiyangdian, said Liu Jing, a senior engineer at Shandong Yellow River Bureau.
Baiyangdian, which is actually a collection of 143 small lakes about 160 km southwest of Beijing, has seen a dramatic reduction in water levels over the past few years.
Last summer's scant rainfall exacerbated the lake's drought, with water levels dropping below 6.5 meters, an official gauge of dryness. Levels fell further to 6.32 m in October.
The diversion of water from China's second longest river to the lake was jointly planned by the State Headquarters of Flood Control and Drought Relief and the Ministry of Water Resources.
It marks the second time that the Yellow River has been diverted to ease the lake's dryness. The first instance was in November 2006, when the lake was hit by the worst drought in 50 years.
Liu said that three of the lake's upstream reservoirs in north China's Hebei Province have been designated as Beijing's back-up water sources during the Olympic Games, which means that they cannot reduce deposits to the lake.
The three reservoirs in Baoding City, Hebei -- Wangkuai, Xidayang and Angezhuang -- are responsible for 300 million cubic meters of back-up water supply to Beijing. Their combined reserves were 467 million cubic meters this winter, or 37.8 percent less than a normal year, because of drought, said Liu.
Baiyangdian, dubbed the "Pearl of North China" is essential to conserve water for the North China Plain. The lake has depended on reservoir water replenishments since 1992. The marshy lake has a total surface area of about 366 square kilometers.