[Photo of Boating activities on
the Shing Mun River]
Although Hong Kong is relatively small in land
area, its steep terrain and high summer rainfall mean it boasts
hundreds of streams, rivers and open storm channels or nullahs right
across the territory. Since Hong Kong is largely surrounded by sea,
none of these watercourses are very long, but they perform a vital
role in draining rainfall off the slopes and efficiently channeling
water into the ocean.
Streams and rivers are used for many different
purposes by Hong Kong’s inhabitants. Many of the territory’s
watercourses are situated in water catchment areas, and flow directly
into reservoirs to provide drinking water for the city. Other rivers
are tapped for irrigation, particularly in those parts of the New
Territories where farming is still carried out. Thousands of urban
Hong Kongers enjoy the peace and serenity that comes from walking
beside rivers, and even boating on some of the larger of them. Last,
but certainly not least, Hong Kong’s streams and rivers are also the
home to a wide variety of fish, insects, and other water life.
Key characteristics of Hong Kong rivers
Hong Kong’s rivers tend to share various characteristics which help
explain how they have been used over time and also why certain
problems have developed. They are all short, with relatively small
flows. The volumes of water they carry can vary quite widely depending
on the season, given Hong Kong’s sometimes torrential summer
rainstorms and its relatively dry winter months. None however are long
enough to develop into the large, deep, slow-moving rivers found in
many bigger places. In addition, the upstream areas of Hong Kong
rivers tend to have been drawn on quite extensively for supplies of
drinking water, a practice that over time has further reduced
downstream river flows. When a river’s flow is reduced, so are its
flushing and self-cleansing abilities, meaning that it becomes easier
for contamination or pollution to build up.
This reduction of flow due to upstream water
use represents just one of a number of key factors that have affected
Hong Kong’s rivers over time. Another is the fact that rivers have for
a long time been used as dumping grounds for waste generated by a
range of human activities, including domestic sewage, livestock waste,
industrial waste, and other types of effluent. This was especially the
case before 1980, when no effective water pollution legislation or
controls were in place.
[Photo of Measuring the flow rate of a river]
This report looks at the
results of monitoring the water quality of a number of key Hong Kong
rivers over the past twenty years, and discusses the work of the
Government and the Environmental Protection Department (EPD) in
improving their water quality. Before exploring this history, however,
it will be useful to lay out some basic geography of Hong Kong that
helps explain the different kinds of rivers in the territory, and the
specific problems that have affected different parts of Hong Kong.
Geographically, Hong Kong’s rivers fall into
four main areas: those of the Eastern New Territories, the
Northwestern New Territories, Lantau Island, and the Southwestern New
Territories & Kowloon. The rivers in each of these four areas tend to
share a number of geographical and historical features. In this
report, information about Hong Kong’s rivers will be divided into four
chapters corresponding with these geographical divisions.
However, this report also frequently makes
mention of ‘Water Control Zones’ for different areas of Hong Kong.
Following the enactment of the Water Pollution Control Ordinance in
1980, the Government began gradually appointing ten Water Control
Zones (WCZs), along with a few Supplementary WCZs, as a way of
focusing its work of controlling water pollution. For the purposes of
monitoring and assessment, Hong Kong’s rivers can also be grouped
according to WCZ. The Water Control Zones are discussed in more detail
in the next chapter, where a map of the WCZs within the four
geographical areas used in this report can also be found.
Eastern New Territories
Within the Eastern New Territories, the EPD monitors a total of ten
rivers, situated within three different Water Control Zones. Within
the Tolo Harbour WCZ the most important is the Shing Mun River in Sha
Tin, but five other rivers in the Tai Po District are also monitored.
Also monitored are three watercourses in Sai Kung (Port Shelter WCZ),
and one near Tseung Kwan O (Junk Bay WCZ).
[Photo of Ho Chung River in the 1980s]
[Photo of Ho Chung River today]
During the 1980s most of these rivers suffered
pollution from a number of sources, but since improvement measures
were set in motion their water quality has improved significantly. A
twenty-year comparison tells the story: in 1986, water at nearly a
quarter (24%) of the Eastern New Territories monitoring stations was
graded either ‘Bad’ or ‘Very Bad’, but in 2005 not a single monitoring
station received either of these gradings. More information about
these gradings can be found in Chapter 2, and detailed information
about the rivers in the Eastern New Territories area in Chapter 4.
Northwestern New Territories
In the Northwestern New Territories, the EPD currently monitors 13
rivers, all situated within the Deep Bay Water Control Zone. They
include the three main rivers of North District, four major rivers
around Yuen Long, and six smaller streams in the vicinity of Lau Fau
Shan.
[Photo of River Indus in the 1980s]
[Photo of River Indus today]
These rivers all suffered greatly in the 1980s
from being surrounded by large numbers of livestock farms, situated in
some of the flattest countryside of rural Hong Kong. Discharges from
numerous unsewered villages scattered across the plains exacerbated
the problem. Significant improvements have occurred since the 1980s,
but the public sewer network still does not extend to much of this
area. The number of livestock farms has been hugely reduced since the
late 1980s, but those that remain still contribute substantially to
river water pollution.
‘Bad’ to ‘Very Bad’ gradings were recorded for
every monitoring station in this area in 1986, and the overall WQO
compliance rate was just 21%. By 2005, the percentage of monitoring
stations graded ‘Bad’ or ‘Very Bad’ had fallen to 42%, and WQO
compliance had risen to 69%. Further information on the gradings and
WQO compliance figures can be found in Chapter 2, and detailed
information on the rivers of the Northwestern New Territories in
Chapter 5.
Lantau Island
On Lantau Island two rivers are monitored, Mui Wo River in the
Southern Water Control Zone and Tung Chung River in the North Western
Water Control Zone. The rivers are relatively remote and Lantau itself
has had a low population base, so pollution has been limited. However,
livestock has long been kept in the Mui Wo hinterland, creating some
pollution problems for that river and silver Mine Bay Beach.
[Photo of Mui Wo River in the 1980s]
[Photo of Mui Wo River today]
In 1986, all the monitoring stations on Lantau
recorded gradings of ‘Fair’, and WQO compliance stood at 72%. By 2005,
all monitoring stations were graded either ‘Good’ or ‘Excellent’, and
WQO compliance had risen to over 99%. Further information on the
gradings and WQO compliance figures can be found in Chapter 2, and
detailed information about the rivers on Lantau in Chapter 6.
Southwestern New Territories & Kowloon
The Southwestern New Territories & Kowloon area runs from Tuen Mun in
the west to Lei Yue Mun at the eastern end of Victoria Harbour. Within
this area, the EPD monitors four rivers and the Kai Tak Nullah. The
Tuen Mun River is in the North Western Water Control Zone, while Kai
Tak Nullah and two minor streams are situated in the Victoria Harbour
Water Control Zone, and another minor stream near Sham Tseng is in the
Western Buffer Water Control Zone.
[Photo of Tuen Mun River in the 1980s]
[Photo of Tuen Mun River today]
The pollution suffered by these rivers in the
1980s varied according to their location, and included livestock,
sewage and industrial pollution. Again, significant improvements have
been achieved over the past two decades. From a total of 80% of
monitoring stations where water was graded ‘Bad’ or ‘Very Bad’ in
1986, in 2005 just 6% of stations received these gradings. The WQO
compliance rate nearly doubled too, from 49% in 1986 to 88% in 2005.
Further information on the gradings and WQO compliance figures can be
found in Chapter 2, and detailed information about the rivers of the
Southwestern New Territories and Kowloon area in Chapter 7.