(BEIJING, Jan. 30) -- The pollution indexes of Beijing's water system have dropped in recent years as a result of the operation of more sewage treatment plants, according to the latest data provided by the Water Quality Monitoring Center of Beijing Drainage Group.

Taking an example of Tonghui River, results of monitoring conducted early December 2006 showed that biological oxygen demand (BOD) fell to 8.50mg/L from 21.6mg/L the same period 2004, and chemical oxygen demand (COD) dropped to 34.6mg/L from 52.2mg/L.

Since 2002 the center has continued test, analysis and regular monitoring on up to 130 items related to water quality, achieving the whole-course monitoring and control of the water quality and environmental impact on the water system in the city.