Supplementary Information Paper for
LegCo Panel on Environmental Affairs
Quality of Dongjiang WaterBackground
At the joint panel meeting on 5 February 1999, Members have requested for more information on the quality of Dongjiang water. This paper provides the requested information in details.Water Supplies from Dongjiang
2. About 80% of our water demand is met by Dongjiang water, which is supplied through an 80-odd km of open transfer aqueduct. The system was first commissioned in the early sixties. In 1989, an agreement was reached between the governments of Hong Kong and Guangdong for adequate water supply to Hong Kong beyond the year 2000. Under the Agreement, the Guangdong side undertook to expand the water supply capacity to 1 100 million cubic metres (mcm) per year. This capacity was planned to be reached by 2008 with an annual increment of 30 mcm per year starting from 1995. The Agreement also stipulated the mechanism to monitor the water supply situation and the quality of water through negotiation.
3. The Agreement was reached through negotiation between the two governments. Should there be any dispute on the interpretation of the terms of the Agreement, such dispute should be settled through discussions at various established channels.
Engineering Works to Assure Quality of Dongjiang Water
4. With the opening up of China, bringing rapid urban development within Southern Guangdong, the expansion of population along the open transfer aqueduct has resulted in deterioration of the quality of Dongjiang water.
5. The Guangdong side has actively implemented a number of engineering measures to improve the quality of Dongjiang water. The major engineering works are (a) the relocation the water intake point at Dongjiang to avoid contamination from one of its distributory rivers; (b) the bio-nitrification plant at the Shenzhen Reservoir; and (c) the proposed conversion of the existing open transfer aqueduct into a closed aqueduct.
6. The water intake point at Dongjiang was relocated in September 1998 to another point where the water quality is better and to avoid the contamination from one of its distributory rivers. The water quality has been improved since the relocation.
7. The bio-nitrification plant at the Shenzhen Reservoir was put into operation in December 1998. A trend of improvement of the raw water is observed. The average chorine dosage for water treatment during the first quarter of 1999 has been brought down to about half of that for the same period in 1998.
8. In 1998 the Finance Committee approved the arrangement of providing an interest-free loan of HK$2,364 million to the Guangdong side to help fund partly the new closed aqueduct project for conveying water from Dongjiang to Shenzhen to improve the quality of water supplied to Hong Kong. In addressing our concern on possible overflow problem, the Guangdong side in return agreed to a reduction in annual water supply quantities from a committed annual increase of 30 mcm to 10 mcm from 1998 onwards until 2004. The Guangdong side also undertook to take into account our future demand growth and reservoir storage when considering the future supply quantities beyond 2004. A value for money analysis was conducted, which indicated that we will have a net saving of HK$240 million.
Environmental Protection Measures
9. Apart from the engineering works, the Guangdong side has undertaken to implement environmental protection measures to ensure the quality of Dongjiang water. At the 10th Hong Kong - Guangdong Environmental Protection Liaison Group Meeting held in November 1998, they reiterated their firm commitment to protect the quality of Dongjiang water. Subsequent to that meeting, they have also provided information on the environmental protection measures, including the planned construction of sewage treatment plants along the transfer aqueduct.
Alternative Intake Point of Dongjiang Water
10. There were also discussions between Guangdong and Hong Kong sides in early 1998 on the suggestion to move the water intake point further north to Xingfengjiang Reservoir, which is over 200 km away from Shenzhen, i.e. Heyuan Scheme. The Guangdong side has rejected this proposal because the Xingfengjiang Reservoir has a major function of regulating the flow of Dongjiang downstream. They pointed out that if other districts of Guangdong put forward the same request, it will lead to adverse effects on the power generation of the Reservoir, and navigation and agriculture downstream, which will upset the ecological balance along Dongjiang.
Trihalmethanes in Drinking Water
11. There were also wide discussions on the probable effect on health of the presence of trihalmethanes, including chloroform, in drinking water. The treated water in Hong Kong conforms completely and consistently with the World Health Organisation (WHO) Guidelines for drinking water quality. The average concentration of trihalmethanes in drinking water is well below the WHO Guidelines.
12. The WHO Guidelines are the consolidated effort of worldwide experts. Compliance with these Guidelines ensures the safety of drinking water and safeguards against any significant risk to the health of the consumers over a lifetime of consumption.