River pollution in Hong Kong represents a huge threat to biodiversity and ecosystems. While water pollution levels are improving, the quality of some watercourses located in rural areas remains low. Examining heavily polluted rivers can help assess the effectiveness of current policies and further enhance the health of Hong Kong rivers. 

Criteria for Measuring River Quality

Despite not being as severe as it was in the past, river pollution in Hong Kong remains a threat to biodiversity and entire ecosystems. Agriculture and industrial activities contribute to the degradation of water bodies, with detrimental consequences on human health and the environment.

Several parameters dictate the pollution level of a water body, including pH, dissolved oxygen, E. coli bacteria, biochemical oxygen demand, suspended solids, phosphorus, and nitrogen. These parameters influence the Water Quality Index (WQI) and the Water Quality Objectives (WQO), both of which are used to quantitatively and qualitatively assess river health. 

river pollution in hong kong; 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. River Water - Our Invaluable Asset Water Quality Index (WQI) for Rivers

Water Quality Index. Source: Hong Kong Environmental Protection Department (HKEPD)

river pollution in hong kong; Water Quality Objectives (WQOs) for marine waters of Hong Kong

Water Quality Objectives. Source: Hong Kong Environmental Protection Department (HKEPD 

The lower the WQO compliance rate (0-100%) and the worse the WQI grade (Very Bad to Excellent), the more contaminated the water body. Contaminated water can lead to prolific water-borne diseases including cholera, diarrhoea, and typhoid. In the latest Annual River Water Quality Report, issued in 2021, Hong Kong river quality was satisfactory, with a compliance rate of 86%. 81% of the river monitoring stations were graded as ‘good’ or ‘excellent’ and only 9% were graded as ‘bad’ or ‘very bad’.

However, unorthodox parameters such as antibiotics and microplastics are often overlooked. Several studies, including Deng et al. (2018), Wu et al. (2020), and Tsang et al. (2020), claim that river antibiotic and microplastic levels are just as important to reduce bacterial-resistant populations and biomagnification. This could worsen as the demand for freshwater resources increases under growing population pressure and economic expansion.

To further improve river quality and keep pollution at a minimum, the government has implemented numerous policies. In this article, we evaluate current river pollution policies and suggest strategies to promote a more river-friendly culture and enhance antibiotic regulations and microplastic monitoring. 

Are Current Policies Effective In Tackling River Pollution in Hong Kong?

1. Expanding Sewage Infrastructure

The Environmental Protection Department (HKEPD) and the Hong Kong Drainage Services Department (HKDSD) have developed a sewage infrastructure system across the territory. Untreated human sewage contains numerous pathogens that cause water-borne diseases and is one of the primary sources of low river water quality. A total of 8 sewerage master plans – design plans of sewage systems – were implemented in 1995 and are regularly reviewed to ensure that the water quality isn’t further altered by increasing population and development. However, there are three key issues related to the sewage master plan. 

The first problem is that rural areas are not being prioritised enough. An example of this can be observed in Tuen Mun, Hong Kong’s westernmost district in the New Territories. Despite being reviewed under the sewerage master plan, there is evidence that rivers in that area still suffer from sewage discharges. In 2021, the monitoring station upstream of Tuen Mun River had a low WQI due to sewage from rural areas. Some might argue that the high urban population outweighs the need of the rural population. Nevertheless, due to rural communities being closer to and dependable on rivers, treatment and monitoring sewerage in rural areas should be prioritised.

Secondly, faulty sewage facilities can harm river systems. Gomes & Wai (2020) point out that, despite the presence of sewerages, rivers in Kam Tin – an area in Hong Kong’s New Territories – were polluted from sewer accidents and breaches. Causes for such breaches may include power outages, intrusion of tree roots in opened cracks, and outdated pipeline systems. This result is consistent with the HKEPD river report, which found that the overall WQO compliance rate in 2021 was 38%, as compared with 21% in 1991. As a result, constant maintenance should be conducted to decrease conduit problems. 

The third and final issue is the cost factor. In addition to the building and operating costs, sewage infrastructure may need additional maintenance and cleaning costs when grease and oil often coming from nearby restaurants in rural areas, enter the system. Such deposits may decrease the sewer’s capacity, resulting in a reduced flow of wastewater. Therefore, the HKEPD and HKDSD ought to cooperate with other stakeholders such as restaurants and country dwellers to reduce sewage at the source.

2. Controlling Livestock Waste

The Livestock Waste Control Scheme under the Waste Disposal Ordinance prohibits the discharge of untreated livestock waste and faeces and sets up prohibition areas for livestock rearing. These regulations could decrease foul odour, suspended solids, and eutrophication in river courses, which are important habitats for aquatic life. 

However, the malpractice of agricultural farmers could be a challenge. To reduce environmental adherence costs, pig and chicken farmers may illegally dump livestock waste into nearby rivers, despite the scheme providing sufficient treatment facilities. This claim is supported since rivers in North Districts and Yuen Long are among the worst in Hong Kong, likely due to the fact that most pig and chicken farms are in northwest New Territories. Livestock waste not only includes antibiotics, but also e. coli, ammonia and nitrogen, which makes illegal dumping detrimental to water quality particularly in individual sections of major watercourses. 

Apart from farmer malpractice, the livestock waste control scheme contains strict guidelines that may not always be feasible. For instance, the soakaway system – a series of channels, screens and pits designed to manage wastewater on-site – will often require long planning and financial investment from farmers, leading to hardships, especially for small-scale farms or family-owned businesses. While the strictness of the scheme can be considered necessary, farmers will likely continue to find loopholes if proper financial assistance and constant monitoring from the government are left unchecked. 

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Policy Suggestions to Reduce River Pollution

1. Promote A River-Friendly Culture

A river-friendly culture can contribute to wastewater reduction. The relatively new term refers to the public interaction with rivers for leisure, enjoyment, and connection with nature. Since the river pollution in Hong Kong is improving, there is a paradigm shift from avoiding to embracing natural rivers. Indeed, rivers can be thought of as a recreational and educational resource instead of a ‘no-go zone’. For successful implementation, it is worth considering various strategies for different rivers, including safety precautions for heavy rain and flooding as well as large-scale infrastructure projects such as the 2006 Yuen Long Bypass Floodway and the revitalisation of Tai Wai Nullah in Sha Tin, which is currently under planning and design. 

The revitalisation of waterways may help promote a more river-friendly culture. The Tsui Ping River in Hong Kong’s Kwun Tong district is a great example of this. Tsui Ping River is set to be revitalised with riverside walkways, footbridges, wetlands, and floating platforms by 2024. The project, which involves the cooperation of multiple government departments such as DSD, EPD, and the Buildings Department, is a great step forward in shaping a more sustainable city and provides an integrated and multi-faceted approach toward river-friendly cultures. Moreover, the proposed wetland and greenery could improve the thermal environment plagued by surrounding highways and skyscrapers.

2. Set a Consumption Standard for Livestock Antibiotics

Antibiotics are drugs that help prevent and treat infections caused by bacteria. It comes without saying that the fewer antibiotics are used on livestock, the fewer end up in rivers. 

Even though antibiotics decrease bacterial infections in livestock such as pigs and chickens, over-consumption causes them to lose their effectiveness over time, giving rise to antibiotic-resistant bacteria. Residues may also run off into rivers through livestock wastewater, disrupting fluvial microbial ecosystems. 

The livestock waste control scheme only focuses on the overall control and treatment of livestock waste but does not specify the limit of antibiotics consumption. High levels of antibiotics such as sulfamethoxazole, sulfadimidine and ofloxacin were detected in some of the most polluted Hong Kong rivers, such as the Yuen Long River and the Kam Tin River. Therefore, similar to the WQO, the government should impose a standard use of antibiotics to reduce pollution at the source.

3. Introducing Microplastics as a WQO Parameter

Under review of the outdated WQO, microplastic concentration can be included as a parameter. With the mass use of single-use plastics in Hong Kong, the risk of microplastic contamination is apparent. 

Microplastics are microscopic fragments resulting from the breakdown of plastics. Common examples include materials such as glitter, microbeads and fragments from larger pieces of plastic debris, as well as from items of clothing. Not only do high concentrations of microplastics lead to biomagnification in aquatic life, ultimately risking public health, but they can also cause stress on wastewater treatment facilities as most are unable to effectively remove all microplastics from wastewater. Therefore, it is important to include parameters like microplastics in WQO to make the assessment of river pollution in Hong Kong more comprehensive and reliable.

An intelligent network management system can be used as a blueprint for introducing microplastics as a WQO parameter. This system focuses on data collection, analysing microplastic particles from water samples and prioritising rivers with high microplastic concentrations. An intelligent network could also use pressure management to reduce the use of non-biodegradable cleaning products, as well as the re-provisioning of water mains such as the upgrade of nearby wastewater treatment facilities that can treat microplastics. 

Although such measures are difficult and time-consuming to implement, finding ways to reduce microplastics in rivers could reduce the overall amount of microplastics transported to the ocean. 

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Final Thoughts

This article aims to raise awareness and provide new perspectives to the current river pollution problems in Hong Kong.

Undoubtedly, the policies and ordinances in place have significantly improved river pollution in Hong Kong. The government’s expansion of sewage infrastructure has reduced the amount of sewage and wastewater entering rivers and the Livestock Waste Control Scheme provides stringent guidelines for waste disposal in nearby rivers.

However, updated technology, a push to reduce farmer malpractice and illegal dumping, as well as the prioritisation of certain pollutants are equally necessary to maintain effective sewage systems. 

Policy suggestions include promoting a friendly river culture under revitalisation projects to integrate the public with the environment, setting a livestock consumption limit for antibiotics to reduce bacterial-resistant population, and including new parameters to the outdated WQO such as microplastics to safeguard wildlife and public health. 

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