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Water Quality Monitoring in Hong Kong
River
Water - Our Invaluable Asset
[Photo of a river in Hong Kong]
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. Monitoring of
the water quality of Hong Kong's rivers is an important part of
the work of the Environmental Protection Department (EPD). It serves
the following purposes:
- To indicate
the state of health of rivers;
- To reveal long-term
changes in the water quality of rivers;
- To assess compliance
with the statutory Water Quality Objectives (WQOs);
- To provide
a basis for the planning of water pollution control strategies.
River
Water Quality Monitoring
[Photo of river monitoring work]EPD
regularly monitors water quality at more than 80 sampling stations
in over 30 rivers and streams in the territory. In situ field
measurements are performed and water samples are collected for further
laboratory analyses mostly on a monthly basis. The monitoring covers
more than 40 parameters including physico-chemical characteristics,
organics, nutrients, toxic metals and coliform bacteria. The rates
of annual compliance with the statutory WQOs are assessed based
on the data obtained during the year.
[Map of River water monitoring stations in Hong Kong]
Water
Quality Index (WQI) for Rivers
[Chart of WQI categories]In
addition to the WQOs, a Water Quality Index (WQI), based on the
level of dissolved oxygen, 5-day Biochemical Oxygen Demand and ammonia-nitrogen,
is used to indicate the extent of organic contamination of the rivers.
The WQI classifies the river water quality into 5 categories according
to the level of organic pollution. In recent years, most of the
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 (http://www.epd.gov.hk).
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