The major rivers in Anhui Province are still seriously polluted with almost half of the water rating at the poorest level, said a yearly environmental bulletin.
Reports from 107 monitoring points along the Anhui section of the Huaihe River and Chaohu Lake show that 44.9 percent of water was rated V on the country's quality scale.
The five-point scale starts at I, the best, and stops at V, the worst, said the environmental bulletin for last year. The provincial environmental protection bureau issued the bulletin on the weekend.
Zhang zhiyuan, chief engineer of the bureau, said the water quality of the main stream of the Huaihe was rated IV on a yearly basis. The water quality at 10 of the 11 monitoring points was rated V from January to April. The rating was better than IV from May to December.
Among the 24 major tributaries of the river, the country's third longest, 16 were rated V, up 14.5 percent from 2003, and 4 were rated IV. The main pollutant in the rivers was ammonia nitrogen, Zhang said.
The water quality of Chaohu Lake - the fifth-largest freshwater lake in the country - was better than the previous year. Eutrophication, the process of proliferating plant life that reduces the amount of oxygen in the water, improved from a serious level to the middle level.
However, among the nine major rivers that feed into the lake, four were rated V and three rated IV, with the major pollutants being ammonia nitrogen and oil.
The bulletin also showed that in 2004 the total drainage of industrial and domestic waste water in the province reached 1.48 billion tons, up 5.1 percent from the previous year. Domestic waste water accounted for 60 percent of that total.
Running through Henan, Shandong, Anhui and Jiangsu provinces, the Huaihe is one of the dirtiest rivers in the country.