The water quality of China's new Three Gorges reservoir has not varied drastically thus far, however, long-term monitoring has to be carried out to determine whether a slower water flow could be pollution-prone.
A source from State Environmental Protection Administration (SEPA) said on Tuesday that the general reading of the reservoir water has remained at level three, or the medium level in China's five-grade index for water quality monitoring, since the reservoir's water level reached its first target depth of 135 meters (445 feet) on June 10.
However, when coliform bacteria content was considered, the water quality dropped to the level five or even lower, as a result of sewage discharge by numerous cities and towns at the upper reaches of the Three Gorges Dam on central China's Yangtze River.
SEPA director Xie Zhenhua said earlier this month that the government has pledged to invest 20 billion yuan (about US$2.4 billion) to build sewage, trash and garbage disposal facilities in all towns and cities in the dam area. Nevertheless, he added, some 40 percent of the planned facilities will not become operational until the end of this year.
"It is very important to build sewage disposal plants to deal with pollution caused by human and livestock excrement," Xie acknowledged.
Daily monitoring beginning in late May found water quality deteriorating during the filling period when the river flow was cut, but it began to improve gradually from June 10, when the flow was partially restored.
The water quality in the mammoth reservoir would be a long-term concern because of slower water flow and the reduced self-purification ability of the river resulting from the building of the giant hydro-electric power dam, the SEPA director said.
Flotage also emerged as a problem after the filling of the vast reservoir behind the Three Gorges Dam, he added. More than 9,800 tons of flotage have been cleared in the past two weeks.
(Xinhua News Agency June 17, 2003)
