Third-stage clearance of Three Gorges Reservoir on the Yangtze River to increase its storage capacity started on Thursday.

Water levels in the reservoir are expected to rise to 156 meters during next year's flood season, according to the Chongqing municipal government.

During this third-stage clearance operation, local governments are required to remove the debris of dismantled houses, factories, waste water and solid rubbish – anything that might pollute the water and that is found below 156 meters.

China started clearing the site of the reservoir, which measures 663 kilometers in length and 58,000 square kilometers in land area, in 2002 with the involvement of Chongqing municipality and Hubei Province.

It is estimated that, in Chongqing alone, some 650,000 tons of household garbage, more than 300,000 tons of industrial solid waste and over 60 tons of dangerous waste, have to be discarded for this stage of the clearing operations, according to the Chongqing municipal government.

"All the waste will be appropriately disposed of to avoid pollution," said an official with the municipal environment protection department.

The Three Gorges Project, of which the reservoir is a major component, requires the relocation of 1.13 million people before it is completed in 2009 when water levels in the river will rise to 175 meters.

China will invest 39.2 billion yuan (US$4.7 billion) in projects to curb water pollution in the reservoir area and upper reaches of the Yangtze River from now until 2010.

The aim of the Three Gorges Project is to control flooding in the middle and lower reaches of the Yangtze. It will also generate hydroelectric power equivalent to 50 million tons of coal annually once generators start operating at full capacity.