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River Water Quality Monitoring in Hong Kong
River Water - Our Invaluable Asset
In Hong Kong, there are hundreds of rivers, streams and open nullahs. They are finite resources having different beneficial uses: such as supply to reservoirs, irrigation, preservation of aquatic life, recreation and passage of storm water to the sea. The EPD has a comprehensive river water quality monitoring programme in Hong Kong since 1986, which covers 82 stations at 30 main rivers and streams running through urban areas. The monitoring involves conducting field measurements and collecting water samples for laboratory analyses of over 50 physico-chemical and biological parameters, including organics, nutrients, metals and E. coli bacteria, serving the following purposes:
- evaluate the pollution status of rivers;
- monitor long-term changes in river water quality;
- provide scientific basis for planning water pollution control strategies;
- assess compliance with the Water Quality Objectives (WQOs); and
- compile Water Quality Index (WQI) to reflect the overall state and trend of the health of rivers.
Water Quality Index (WQI) for Rivers
 In addition to the WQOs, a Water Quality Index (WQI), based on assessment on the level of dissolved oxygen, 5-day Biochemical Oxygen Demand and ammonia-nitrogen, is used to indicate the overall status of health of rivers. These parameters are relevant to conserving the primary beneficial use for maintenance of aquatic life, and are collectively used to gauge the extent of organic pollution in a river. The WQI classifies river water quality into 5 categories according to the level of organic pollution. In recent years, most rivers in Hong Kong are within the "Fair" to "Excellent" range.
Information on River Water Quality and Hong Kong's Environment
Detailed information on Hong Kong's river water quality is published in the annual report River Water Quality in Hong Kong. This report is available in public libraries and Environmental Resource Centres, and can be downloaded from EPD's River Water Quality Web Page. Other information on Hong Kong's environment can be obtained from EPD's homepage (https://www.epd.gov.hk/).
Location of River Monitoring Stations
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