The Asian Development Bank (ADB) has approved loans of 800 million U.S. dollars to east Anhui province to improve the water and surrounding environment of a major lake, local authorities said Tuesday.

The loans will be used to intercept sewage flowing into the Chaohu Lake, dredge the tributaries, renovate dikes, build lake bank roads as well as reinforce environmental monitoring, said an official with the development and reform commission in the provincial capital of Hefei.

The bank is already handling the first loan of 250 million dollars, and it is so far unknown when the rest of the loans will be in place.

As one of China's five largest freshwater lakes, Chaohu Lake, mostly situated in the city of Hefei, covers an area of 13,000 square kilometers.

Heavy use and local industrial development in recent years have made it one of China's most polluted lakes.