Climate change and major water conservation projects are a major risk to the long-term "health" of the Yangtze River, claimed a report released at the weekend.

The Yangtze Conservation and Development Report 2009, compiled by the China Academy of Science (CAS), states the basin of China's longest waterway has been hit by a yearly reduction in rain since 2006, brought on by global warming.

Annual rainfall dropped 10.3 and 6.9 percent respectively in 2006 and 2007, the report said, while severe droughts in 2007 and last year resulted in the shrinking of two of the nation's biggest freshwater lakes, Poyang and Dongting.

The research also estimated that by 2030 the glacial area at the source of the Yangtze River will be reduced by 6.9 percent from the level recorded in 1970.

"Long-tem observation and multi-disciplinary studies on possible impacts are needed to better understand what climate change will do to the river," said Yang Guishan, a CAS researcher and an author of the report.

The massive Three Gorges Dam project is also damaging the overall water quality, ecosystems of the wetlands and fish stocks, said the report.

The research showed that with a hike in the concentration of nitrogen and phosphorus, the water quality in reservoir areas of the Three Gorges Dam has deteriorated since it began water storing in 2003.

An increase in outbreaks of algae caused by excessive nutrients in the water has also been found in the reservoirs, said the report, while the Three Gorges Dam and other conservation projects are disrupting migration routes for fish and changing the ecology of the fish spawning sites in the Yangtze River.

The report found a steady fall in the number of black carp, grass carp, silver carp and crucian carp since 2003.