More than 33.3 billion tonnes of waste water was discharged into the Yangtze River basin last year, according to Xu Deyi, spokesman of the Yangtze River Water Resources Committee, on Monday.

Waste water discharged annually into the Yangtze River, its tributaries and lakes along the country's largest river was about 9.5 billion tonnes in the 1970s, 15 billion tonnes in the late 1980s, and 20 billion tonnes in the mid and late 1990s, Xu said.

The proportion of industrial waste water declined by one percentage point from 2008 to 66.4 percent in 2009 as the government closed high polluting companies, he said.

However, the proportion of domestic waste water in urban areas rose slightly to 23.4 percent in 2009, from 23 percent in 2008.

The water quality in the Yangtze River rose slightly last year, but the challenges for fighting pollution remained daunting, he said.

In addition, floods this summer caused 122 billion yuan in economic losses in 1,046 county-level regions in the Yangtze River basin by the end of August, Xu said. Floods also killed 449 people and left 335 missing in the regions.