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Title: Can HAB’s be consigned to history: lessons from Tolo Harbour, 1986 to the present


Dr. Gordon S. MAXWELL
School of Science and Technology
The Open University of Hong Kong


This paper presents a strong case advocating that the resent findings showing the declines in HAB events in Tolo Harbour show a way forward in rejuvenating the EIA Ordinance, its Guidance Notes and Technical Memorandum. Research on Non-point Pollution ( NPP) within the North East NT catchment show that such eutrophication still exists and contributes to pollution within the Tolo Harbour, but due to the success of the Tolo Harbour Action Plan ( THAP) an overall decline in nutrient inputs into the Harbour is evident. The nature of the NPP is outlined and developed into suggestions on how to build on THAP to embrace much bigger concepts and models of sustainable development, including aspects of the industrial ecology paradigm and its daughter concept of the circular economy.

1. Introduction

HAB (~ ‘Red Tide’) incidents have been a feature of the coastal environment of Hong Kong for decades. However, the recent pattern of declines in HAB incidents (HAB’s) in the Tolo Harbour have been evident since 1991 and a marked decrease has been recorded in the period 2006-2010. A key underlying contributor to this success has been Tolo Harbour Action Plan (THAP) set up in 1987 and sustained over the past 28 years. Early success was based on marked reductions in livestock waste. More recently with the intensification of land use changes characterized by housing and associated challenges to sewage treatment, the opportunity to sustain these environmental improvements has been identified. The essence of this opportunity rests on a bold yet realistic application of EIA thinking, methods and objectives to land use on a household scale. Powerful evidence that Non point pollution (NPP) from the Tolo Catchment is today the main factor behind HAB’s within the Tolo Harbour is available (see Hung, 2013). This comprehensive research can provide much needed confidence to re-fresh the philosophy & power of our existing EIAO, its Guidance Notes and T.M. Thus this paper argues that a rejuvenated EIA Ordinance could furnish a tool for the emergence of measurable sustainable development in the Eastern New Territories (Catchment for the Tolo Harbour) and sustainable use of the Tolo Harbour. Success in the Tolo Harbour and environs could spread region wide and bring with it welcome aspects of a circular economy which are emerging in China.

2. Key definition:

Non-point pollution (NPP)

The following definition is a synthesis based on a critical evaluation of U.S. EPA sources: Any source of water pollution that is not delivered by a discrete human-made conveyance such as a pipe, tunnel or conduit. In practice non-point pollutants such as agricultural chemicals (pesticides, fertilizers), oils and toxic chemicals from industry, disturbed sediment and disorganized soils, microbials and atmospheric chemicals have all been moved by rainfall that becomes surface water and run off that typically flows in catchments of rivers and streams reaching coastal marine waters. In a sense NPP can be covert rather than overt and may therefore be looked upon (incorrectly) as relatively normal, like storm-water flowing over land during a rainstorm, typhoon or other wet-day down pour.

3. Tolo Harbour as ‘teacher’


This paper contends that we in HKSAR should pay our collective respect to an impressive body of research that points the way forward in EIA thinking as it could be applied to wise land use. Then evidence that Non Point Pollution (NPP) is a key factor in coastal marine water quality and HAB incidents is impressive, spanning over three decades e.g. Lam (1980); Hodgkiss & Chan (1986); Lee (1990); Ho (1991); Ho & Hodgkiss (1993); Li et al (2003); Li et al (2005); Hung (2013).

3.2 Do pollution controls work in HKSAR?

The very recent findings of a comprehensive 24 month research project on NPP in Eastern New Territories (ENT) (~HAB’s) and the Tolo Harbour demonstrates that anti-pollution measures can be impressively effective (see Hung, 2013).

3.3 Measuring pollution: Red tide incidents as indicators of recent pollution history in HKSAR

Red tide incidents (RTI’s) have increased in Hong Kong coastal waters generally in the period 1991 to 2010 but, impressively and importantly have declined in Tolo Harbour (EPD data and Hung, 2013). This is surprising as the geomorphology of Tolo Harbour - a bottle shaped Harbour with sluggish tidal flushing (Ho, 1991) - tends to retain pollutants. In this paper I focus on Tolo Harbour because herein lies the ‘lesson’ and inspiration for fresh re-evaluation of our HKSAR EIA ordinance. During the 24 months of Hung’s (2013) research (January 2009 to December 2010) some 56.87 tons of eutrophicating nutrient was delivered as NPP to the Inner Tolo Harbour; especially the Inner Tolo Harbour. Of this, 79.95% was Nitrogen (Table 1).

Table 1 Macrocomposition of NPP input into Tolo Harbour between Jan. 2009 and Dec. 2010)


Macronutrient % (of 56.87 tons)


Total Inorganic Nitrogen (TIN) 63.6

Ammonia-Nitrogen 16.36

Combined N input 79.95

Ortho-phosphate 20.05


(Data from: Hung (2013))

Perhaps not surprisingly within the ENT catchment the Lam Tsuen River discharged the highest nutrient load. This was 4.5 times more than that of the Tai Po Kau Stream; a watercourse that benefits from receiving rainfall run-off filtered by a relatively mature forest ecosystem: Tai Po Kau Nature Reserve (TPKNR) consists of 460 ha of old plantation (1926 planted). Today some 100 tree species and 160 bird species (Kwok, 2001; 2002; Owen & Shaw, 2007) attest to TPKNR’s ecosystem maturity and value as an ecological resource. There was a clear correlation between annual rainfall levels and HAB incidence especially in the Inner Tolo Harbour. Dinoflagellates - the best known contributors to HAB’s due to toxin formation - increased relative to other phytoplankters during the period 1978 to 2010 (Hung, 2013) and this trend was in phase with an aquatic N:P ration strongly in favour of Nitrogen.

Fortunately, while these ecotoxicologically unwelcome marine phytophlankton increased relative to the less harmful diatoms and silicoflagellates, the overall incidence of HAB’s declined. This decline heralds an opportunity to consider our current anti-pollution and environmental laws with a review to their re-juvenation, enhancement and popularization as tools to uplift both environmental quality and how we could make sustainability a household word.

4. How an enhanced EIA system can contribute to reduced HAB’s and a circular economy

4.1 Enhanced EIAO

While useful and respected in HKSAR, our EIAO, its Guidance Noted (GN’s) and Technical Memorandum TM invites improvement and enhancement: (e.g. see Maxwell, 2004; 2015). Two key areas inviting enhancement are * the loop holes associated with only designated projects requiring an EIA and * GN’s which focus on relatively simple ecology built around species lists to identify rare or endangered species.

The designated project approach tends to result in EIA thought and action becoming restricted to what are perceived as ‘big’ projects. This restriction dilutes the identification and characterization of cumulative impacts. GN’s which place species lists and short duration surveys as an acceptable norm results in EIA reports which are lean on interspecific ecological interactions and thus ecosystem functionality.

Collectively, the loop holes created by having EIA’s for designated projects only and by limiting the depth of ecology addressed in an EIA, greatly underutilizes EIA as a tool for enhancing environmental quality and genuine sustainable use of ecological resources. In concluding her thesis on NPP in the Tolo Harbour and its catchment Hung (2013) advocated that better town planning and infrastructure development be introduced to contain NPP. Measures such as more advanced rainwater run off management, rainwater re-cycling (capture and use) and importantly, the prevention of illegal dumping. An enhanced and localized application of EIA thinking could be the tried and tested tool to facilitate these measures. In unison with a love your Hong Kong campaign, the enhancement of EIA awareness for all could make acts such as illegal dumping be seen as both anti-social and anti-environmental.

The spark or intellectual and societal energy for such EIA enhancement and popularization is here: it is the decline of HAB’s in the Tolo Harbour. In this way EIA could become a tool for Hong Kong people to become guardians of environment quality.

4.2 Towards a circular economy

The Circular Economy model (Yuan et al 2006) integrates ecological, social, industrial components into something approaching a system of socio-economic strategy which is sustainable and devoid of environmentally harmful outcomes, especially toxic wastes. In short, a holistic approach to eco-economics which encourages industry, town planning &design to become more ecological in structure & function. The core concept underlying the circular economy is that it is modeled on the ecosystem and therefore free from waste: the unused or left over products of one industry or human activity become the resources of another industry. The concept has been formally accepted by the central government thus giving the paradigm of industrial ecology top level status in China. By building on the success of improving environmental standards in the Tolo Harbour region of HKSAR covering land and water, we could show how the triple winners of scientific (ecologically sound) balanced and harmonies development can unite to bring sustainable development (Maxwell, 2015,b). I am sure that the central government of China would welcome this demonstration of how a circular economy model could become a reality.

This paper makes a case for the enhancement, localization and popularization of EIA as a tool to help bring the admirable and much needed paradigm of a circular economy first to the Eastern N.T. and Tolo Harbour and then to HKSAR.

5. Countering the counter arguments: defusing the doubters

5.1 Impossible dream?

There will be those in Hong Kong society who will cry that to make EIA a popular tool for living in a sustainable HKSAR, is an impossible dream. The same people may choose to argue that even in ‘clean and green’ countries such as New Zealand, EIA is distant from everyday life. Such people typically miss a vital; point. While most people do not produce formal EIA statements or documents, all people in NZ have the right in law (Resource Management Act or RMA) to contribute to the EIA process. Indeed, it has been shown that an EIA mentality is now well established in the public mind (see e.g. Maxwell 2004; 2015a). This reality was strongly evident in a major marina development project involving coastal waters and mangrove ecosystems (Maxwell, 2006).

That people can become EIA aware and active is a reality and even in HKSAR we should not underestimate this potential. Let us not forget that this potential has been evident in HKSAR for some considerable time (e.g. Ho et al 1999; Fen, 2003; Maxwell, 2003).

5.2 East N T has unique drainage features?

Hung (2013) did report that there were important variations in water volumes from water course to water course. These variations were linked, as one would perhaps expect, to patchy distributions of rainfall and the sometimes local nature of flash floods. However, this ‘pulsed’ nature of water flow is typical of Hong Kong streams (Dudgen & Corlett, 1994).

Clearly, ENT is not unique in terms of rainfall distribution and stream water volume. This Tolo Harbour is, in contrast, unique. As mentioned 3.3. above the bottle neck shape of the harbor entrance contributes to long retention times for nutrients in the water column. Against this background to witness welcome reductions in HAB incidents is most impressive and a source of inspiration on which to build further success in environmental improvement across HKSAR.

Furthermore, the patchy rainfall patterns and ‘pulses’ in stream volume add weight to the theme of this paper: the extension and intensification of an EIA awareness could do much to enhance day to day pollution reduction. The recent success in HAB reduction in the Tolo Harbour highlighted in this paper has the potential to re-ignite the energy we may need show that EIA in the 21st Century is part of both local and global citizenship.

6. Concluding thoughts

The theme of this paper is that we in HKSAR should capitalize on the success of Tolo Harbour Action Plan (THAP) started in 1987 and the uplifting recent findings on declining HAB’s in Tolo Harbour to re-juvenate EIA thought and action.

Other far more complex and difficult trends in ecological awareness are upon us. These include the paradigm of industrial ecology and its daughter concept of the circular economy. The New Agricultural Policy (NAP) published in December 2014 also embraces the same trend with its focus on better land use, safer food, re-cycling and the wisdom of educating modern people to respect land, soil, water and ecosystems. Here we perhaps should pose the question, why do we need to wait until land is misused before we apply laws like the Land Resumption Ordinance (Cap. 124) to re-capture misused NT land for areas like agri-parks, when with real EIA thinking we could make an agri-garden and eco-area in or near all NT villages and housing estates. Respect for Nature is not new in HKSAR. Indeed it has a deep and long cultural history of which fung shui woodlands integrated with traditional village plans are an example. Maxwell & Hung (2008) compared how traditional cultural attitudes in New Zealand and Hong Kong can be a successful component of ecological resource wise use. There is even an ecotourist potential to the story where tourists seeking hands-on, positive, helpful local experiences can become eco-restoration volunteers (Maxwell & Hung, 2005). Tourists may like to embrace a clean a stream (CAS) and come to ENT & Tolo Harbour to play their part in applied sustainable behaviour (ASB)!

Other threads of opportunity also run with these ideas. The wise use of water is one and is a crying need in HKSAR where some 135,000m3 (cubic metres) of potable water are used per day. Water capture, retention and recycling mentioned in 4.1 above returns to our thinking here. Very recently, Zhang (2015) highlighted the huge water issue facing China today when he claimed that the top environmental challenge in China is safe water. The China Central Government would like to cap overall water consumption at 670 billion m3 by 2020. The key to success here may well lie in big reductions in agricultural and industrial misuse with education not regulation the best approach. By acting at local level of ENT & Tolo Harbour we in HKSAR, may help to demonstrate how this water resource can be part of an Environmental Re-evaluation Scheme using a re-juvenated EIA as the main tool. “Hong Kong has unparalleled natural endowments, with better environmental protection Hong Kong can be the loveliest city in the world.” (P.47, The 2013, Policy Address). To achieve this, indeed to sustain this, “the Government and the community must commit to improving the environment” (2013. Policy Address).

Clearly, we must begin to think and act ecologically beyond Country Parks (CPs). Overemphasis on CPs by some ‘Green Groups’ tends to deflect people away from developing a personal ecological mentality.

The theme advocated in this paper aims at using the success of the Tolo Harbour Action Plan and its attendant reduction in HAB’s as an encouragement to apply EIA at a house-hold level, along with local Building standards and safety requirements. Impacts as shown by the nutrient inputs into the Tolo Harbour (Table 1. Section 3.3 above) clearly remind us and demonstrate that small scale, non-point pollutants add up. Impacts are cumulative and algal blooms, harmful or benign, are symptoms of this fact.


I would like to thank Professor K.C. Ho, JP, BBS for inviting and encouraging me to give this paper. Thanks, too, to Ms. Karen Hung BA, M Phil for granting me permission to use her thesis on Tolo Harbour and non-point pollution. I wanted to make this a joint paper like the others mentioned in the references but this was not possible.


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