20 Years of Marine Water Quality Monitoring in Hong Kong

| Director's Message | Introduction | Background of the EPDs river water quality monitoring programme | The scientific basis of the EPDs river water quality monitoring programme | River water sampling procedures: testing, analysis, and publication of results | Eastern New Territories | Northwestern New Territories | Lantau Island | Southwestern New Territories & Kowloon | Summary | Appendices | Acknowledgements | Disclaimer |

Background of the EPDs river water quality monitoring programme

The EPD’s river water quality monitoring programme

Back in 1986, many of Hong Kong’s rivers were in a bad state. The river network was experiencing severe water pollution at many levels, so much so that some rivers had become too polluted to support life and were black and foul-smelling. Besides the environmental impact of such pollution, human health was at risk too, as some rivers were heavily contaminated with human and animal waste.


As mentioned in the Introduction, the major pollution sources at this time were threefold. First, waste from a multitude of livestock farms (pigs, chickens and other poultry) either washed into rivers or was channeled into them. Second, hundreds of villages across Hong Kong without public sewerage relied on inefficient septic tanks or else simply directed their wastewater flows into nearby streams. Third, at a time when Hong Kong still had a significant industrial presence, commercial premises too often relied on expedient connections that saw their discharge washed into rivers and from there into the sea. 

[Photo of A river polluted by waste from duck farming]

[Photo of Brightly-coloured factory discharge]

The EPD’s system for assessing river water quality will be described in detail in Chapter 2. Suffice it to say for now that in 1986, the first year in which the newly formed EPD began monitoring river water quality, some 45% of its monitoring stations produced results that graded the river water as ‘Bad’ or ‘Very Bad’. The following year water quality deteriorated even further, with 54% of monitoring stations recording ‘Bad’ or ‘Very Bad’ gradings. Simply put, Hong Kong’s river system was reaching a crisis point, and concerted action was needed in order to put a stop to the degradation of this crucial natural resource.



Government response: the Water Pollution Control Ordinance

[Photo of A guide to the Water Pollution Control Ordinance is available on the EPD website]

In the face of this deterioration in river water quality, the Government over the past twenty years has inaugurated a series of control measures designed to reverse the trend. The foundation stone for this package of measures was the enactment of the Water Pollution Control Ordinance (WPCO) in 1980. This legislation put in place a basis for controlling pollution in the waters of Hong Kong.


The Ordinance and later subsidiary legislation allowed the Government to declare Water Control Zones (WCZs) within Hong Kong. Each WCZ declared by the Government would have a set of Water Quality Objectives developed that were appropriate for its characteristics and its ‘beneficial uses’ (an expression that refers to what the water in question is mostly used for, as for example drinking, recreation, irrigation etc). This means that Water Quality Objectives may differ from one WCZ to the next. These Water Quality Objectives scientifically express the levels of water quality necessary to achieve the conservation goals for each WCZ.


As each WCZ was declared, the EPD was given the job of enforcing pollution controls in it with the goal of achieving and maintaining the specified Water Quality Objectives for that WCZ. One major means of control was a licensing system. Apart from the discharge of domestic sewage into public sewers, under this system all industrial, commercial, and institutional premises were required to obtain a licence if they wanted to discharge effluent. Each licence specified the terms and conditions of discharge including what pre-treatment was necessary, and laid out the standards to be met. The EPD was given the power to inspect all those discharging effluent to ensure that they were complying with the terms and conditions of the discharge licence. This would also involve making sure that wastewater treatment facilities were being properly operated and maintained. In addition, the EPD was given the authority to require property owners to connect their wastewater to the public sewer system as it became available.


The WCZs were appointed gradually between 1987 and 1999. The accompanying map shows all ten WCZs and Supplementary WCZs and the dates when they were first appointed. Each WCZ was divided into subzones, and each subzone was allocated a specific set of Water Quality Objectives. These Water Quality Objectives include a series of clear parameters for assessing the quality of the water in each WCZ. Those key parameters that the EPD monitors and uses for calculating the WQO compliance rate include pH, dissolved oxygen, 5-day biochemical oxygen demand, chemical oxygen demand and suspended solids. More detail about these parameters, and how and why they are monitored, is given in Chapter 2.

[Photo of Map of the Water Control Zones and the dates they were first appointed]


The Livestock Waste Control Scheme

[Photo of A Guide to the Livestock Waste Control Scheme is distributed to livestock farmers]

A further Government initiative to reduce and control water pollution was the Livestock Waste Control Scheme, implemented under the Waste Disposal Ordinance, which was introduced in 1987 and further revised in 1994. The Scheme came about in response to the massive and indiscriminate discharge of untreated livestock waste into rivers in the New Territories. This major initiative designated a series of Prohibition Areas in which the keeping of livestock was completely banned after 24 June 1988. The Scheme significantly reduced the pollution from livestock farms in Hong Kong. The accompanying map shows the areas designated as Prohibition Areas, mostly within and around built-up urban areas.


Farmers outside the Prohibition Areas were permitted to continue rearing livestock, but they were required to properly dispose of their waste and treat their effluent so that it complied with standards of no more than 50 mg/L of suspended solids and 50 mg/L of 5-day biochemical oxygen demand by the mid-1990s.


The Government took several steps to help farmers cope with the new regulations. It gave them technical help by publishing a code of practice and guidelines on waste treatment options, and by setting up a private farm demonstration treatment plant. It also established a free livestock waste collection service, and made financial help available for farmers to install their own waste treatment facilities. Finally, the Government provided incentives for farmers for whom the new system was too difficult: it offered eligible farmers an ex gratia allowance if they chose to close down their livestock business completely. 

[Photo of Map of Livestock Waste Prohibition, Restriction and Control Areas]


Sewerage Master Plans

Despite the fact that the WPCO had laid down clear objectives for water quality in Hong Kong, the Government recognised that achieving these objectives would depend heavily on building a comprehensive territory-wide sewerage system. To move towards this goal, between 1987 and 1996 the Government produced 16 Sewerage Master Plans covering the entire territory. The accompanying map shows the 16 different areas for which individual Sewerage Master Plans have been developed.


These plans provide a blueprint of the sewerage infrastructure needed to collect sewage in each water catchment area across Hong Kong and transport it to sewage treatment plants. These Master Plans have been reviewed in the light of updated population forecasts and changing patterns of development. The recommendations contained in these Master Plans and their reviews are being progressively implemented across Hong Kong.

[Photo of Map of the 16 Sewerage Master Plans]


To assess the effectiveness of the steps taken over the past couple of decades to reverse the pollution of the rivers and streams in Hong Kong, the Government has relied heavily on the EPD’s River Monitoring Programme. This programme has provided the objective scientific data by which it has been possible to see to what extent the initiatives have contributed to improving water quality, which geographical areas need the most attention, and which problems need further work to overcome. With the information provided by the programme, Government planners and policy makers, environmentalists and the general public can make informed decisions about our river resources and what needs to be done to protect and preserve them.



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