CONTENTS

7. ECOLOGICAL Impact Assessment 2

7.1 Introduction 2

7.2 Statutory Requirements and Evaluation Criteria 2

7.3 Assessment Area 6

7.4 Methodology for Baseline Establishment 6

7.5 Baseline Condition 8

7.6 Identification of Ecological Impacts 9

7.7 Potential for Cumulative Impacts 27

7.8 Mitigation 29

7.9 Precautionary Measures 45

7.10 Residual Impacts 45

7.11 Monitoring and Audit Requirements 47

7.12 Conclusion 47

7.13 References 50

7 ECOLOGICAL IMPACT ASSESSMENT

7.1Introduction

7.1.1 The EIA Study Brief (SB) No. ESB-307/2018 for the Project issued on 9 March 2018 has stipulated the technical requirements for ecological impact assessment (EcoIA), in Section 3.4.6 and Appendix D of EIA SB. The aim of the EcoIA is to protect, maintain or rehabilitate the natural environment, in particular to avoid or minimize impacts on recognized sites of conservation importance and other ecologically sensitive areas such as the Mai Po Inner Deep Bay Ramsar Site, Wetland Conservation Area (WCA) and Wetland Buffer Area (WBA), and mudflats / mangrove at Kam Tin River (KTR) and Shan Pui River (SPR). The assessment is intended to identify and quantify as far as possible the potential ecological impacts arising from the Project including its construction and operation phases as well as subsequent management and maintenance of the Project.

Key ecological issues stipulated in EIA Study Brief

7.1.2 Key ecological issues stated in the EIA Study Brief included but not limited to the following:

(a) Natural and man-made wetland habitats including mudflats, mangrove, streams, drainage channels, fishponds, freshwater ponds, reedbeds, marshes and others, in particular the mudflats at Shan Pui River and Kam Tin River exposed during low tide, as well as roosting areas of Black-faced Spoonbill and Great Cormorant;

(b) Migratory and overwintering waterbirds roosting and/or feeding in the wetland habitats above;

(c) The active egretry at Tung Shing Lei (TSL) and the egrets and herons breeding there;

(d) Intertidal/benthic communities;

(e) Mammals, in particular Eurasian Otter;

(f) Fireflies in particular Bent-winged Firefly; and

(g) Any other habitats and species identified as having special conservation importance by this study.

7.1.3 This Section presents the findings of an assessment of the potential ecological impacts associated with the construction and operation of the proposed Project for Yuen Long Barrage Scheme. It summarizes baseline information gathered from the literature review and baseline ecological surveys on the ecological resources in the assessment area, and describes the ecological importance of this area.

7.2 Statutory Requirements and Evaluation Criteria

General

7.2.1 The relevant ordinances and regulations that are applicable to this EcoIA include the followings:

· Forests and Countryside Ordinance (Cap. 96) and its subsidiary legislation, the Forestry Regulations;

· Wild Animals Protection Ordinance (Cap. 170);

· Environmental Impact Assessment Ordinance (Cap. 499) and the associated Technical Memorandum (EIAO-TM); and

· Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586) and its subsidiary legislation.

7.2.2 This EcoIA makes reference to the following guidelines and standards:

· Hong Kong Planning Standards and Guidelines (HKPSG) Chapter 10, “Conservation”;

· PELB Technical Circular 1/97 Works Branch Technical Circular 4/97, “Guidelines for Implementing the Policy on Off-site Ecological Mitigation Measures”;

· EIAO Guidance Note No. 3/2010 – Flexibility and Enforceability of Mitigation Measures Proposed in an EIA Report;

· EIAO Guidance Note No. 6/2010 – Some Observations on Ecological Assessment from the Environmental Impact Assessment Ordinance Perspective;

· EIAO Guidance Note No. 7/2010 – Ecological Baseline Survey for Ecological Assessment;

· EIAO Guidance Note No. 10/2010 – Methodologies for Terrestrial and Freshwater Ecological Baseline Surveys; and

· EIAO Guidance Note No. 11/2010 – Methodologies for Marine Ecological Baseline Surveys.

7.2.3 This EcoIA also makes reference to the following Mainland legislation:

· List of State Protected Wild Animals, promulgated by the State Council 國家重點保護野生動物名錄; and

· List of Wild Plants under State Protection國家重點保護野生植物名錄(第一批).

7.2.4 Other international conventions and guidelines that are relevant to this EcoIA include the following:

· Convention on International Trade in Endangered Species of Wild Fauna and Flora ("CITES"). This Convention regulates international trade in animal and plant species considered to be at risk from such trade. Depending on the degree of threat posed by international trade, CITES classifies endangered species of animals and plants into three Appendices. Appendix I includes highly endangered species threatened with extinction. Commercial trade in these species is prohibited. Appendix II includes species which are not presently threatened with extinction but may become so unless trade is controlled. Trade of these species is allowed but is subject to licensing controls. Appendix III species are species identified by any Party to CITES as requiring cooperation in controlling their trade. Their trade is subject to permits or certificates of origin. Hong Kong's obligations under this Convention are enforced via the Protection of Endangered Species of Animals and Plants Ordinance (Cap. 586). The CITES authority for Hong Kong SAR is the Department of Agriculture, Fisheries and Conservation (AFCD).

· IUCN. The World Conservation Union maintains, through its Species Survival Commission, a “Red List” of globally threatened species of wild plants and animals (see http://www.iucnredlist.org). The Red List is considered the authoritative publication to classify species into nine groups as Extinct (EX) - No individuals remaining; Extinct in the Wild (EW) - Known only to survive in captivity, or as a naturalized population outside its historic range; Critically Endangered (CR) - Extremely high risk of extinction in the wild; Endangered (EN) - Very high risk of extinction in the wild; Vulnerable (VU) - High risk of extinction in the wild; Near Threatened (NT) - Likely to become endangered in the near future; Least Concern (LC) - Lowest risk. Does not qualify for a higher risk category. Widespread and abundant taxa are included in these two categories: Data Deficient (DD) – Knowledge of the species is inadequate to enable assessment its risk of extinction; and Not Evaluated (NE) – Species not yet evaluated against the criteria.

· United Nations Convention on Biological Diversity. This convention requires parties to regulate or manage biological resources important for the conservation of biological diversity whether within or outside protected areas, with a view to ensuring their conservation and sustainable use. It also requires parties to promote the protection of ecosystems, natural habitats and the maintenance of viable populations of species in natural surroundings. The People’s Republic of China (PRC) ratified the Convention on Biological Diversity on 5 January 1993. The HKSAR Government has stated that it is "committed to meeting the environmental objectives" of the Convention (PELB 1996).

· Convention on Wetlands of International Importance Especially as Waterfowl Habitat (the "Ramsar Convention"), which requires parties to conserve and make wise use of wetlands, particularly those supporting waterfowl populations. The PRC ratified the Ramsar Convention on 31 July 1992, and various wetlands have since been listed as wetlands of international importance (i.e. Ramsar sites). One of these, Mai Po Marshes and Inner Deep Bay Ramsar site in Hong Kong SAR, was listed on 4 September 1995.

· Convention on the Conservation of Migratory Species of Wild Animals (the Bonn Convention), which requires parties to protect listed threatened or endangered migratory species occurring within their boundaries.

Criteria of evaluating species of conservation importance

7.2.5 Species of flora and fauna with conservation importance were given special attention. In accordance with Table 3, Annex 8 of the EIAO-TM, the ecological value of species was assessed in terms of protection status, distribution, and rarity. For faunal species, the protection status (e.g. fauna protected under Cap. 170 (except birds as all wild birds are protected under the ordinance but their conservation importance is not equal), Cap. 586, and/or regional/global laws/conventions), the species distribution (e.g. endemic), and the rarity (e.g. rare or restricted, or level of concern highlighted in Fellowes et al. (2002)) were considered. Similarly, floral species of conservation importance are considered from protection status (e.g. listed under Forestry Regulations and Cap.586 in Hong Kong, listed by IUCN or CITES, or listed as Category I or II protected species in mainland China); species distribution (e.g. endemic); and rarity (e.g. considered rare or very rare by Corlett et al. (2000) and regarded as rare by Yip et al. (2010)). However, exotic invasive species, escaped cultivars or captive species, vagrants and introduced species are excluded.

7.2.6 The following laws/regulations and conventions for conservation were relevant with evaluation of the conservation importance of flora and fauna species.

· Forestry Regulations (Cap. 96A) which are subsidiary legislation of the Forests and Countryside Ordinance (Cap. 96);

· Category I/II/III in List of Wild Plants under State Protection;

· Considered ‘Rare’ or ‘Very Rare’ plant species listed by Corlett et al. (2000) and regarded as ‘Rare’ plant species by Yip et al. (2010);

· China Plant Red Data Book;

· Threatened Species List of China’s Higher Plants (Qin et al., 2017);

· Wild Animals Protection Ordinance (Cap 170);

· Protection of Endangered Species of Animals and Plants Ordinance (Cap 586);

· Category I or II State Protected Wild Animals;

· PRC Wild Animal Protection Law;

· China Red Data Book of Endangered Animals;

· China Species Red List;

· Red List of China’s Vertebrates;

· The International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species (Species which are classified by IUCN as Near Threatened (NT), Least Concern (LC), Data Deficient (DD), or Not Evaluated (NE), and not covered by any other laws/regulations/conventions are not considered of conservation importance in the present EcoIA);

· The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES); and

· Fauna species considered of concern in Fellowes et al. (2002).

7.2.7 The species identified from both literature review and the ecological surveys as having conservation importance were further categorized in accordance with their relevance to potential impacts, which were assessed in accordance with the EIAO-TM criteria.

7.3 Assessment Area

7.3.1 As stated in Section 3.4.6.1 of EIA SB, the assessment area for the purpose of EcoIA includes all areas within 500m distance from the site boundary of the Project and other areas likely to be impacted by the Project. For aquatic ecology, the assessment area is the same as the water quality impact assessment i.e. include areas within 500m from the site boundary of the Project and cover the Deep Bay Water Control Zone as designated under the Water Pollution Control Ordinance and the water sensitive receivers in the vicinity of the Project.

7.4 Methodology for Baseline Establishment

Literature review methodology

7.4.1 A literature review was conducted to characterize the existing conditions within the assessment area and to identify habitats and species of potential importance in the area. The literature review covers Government and private sector reports, independent and Government published literature, academic studies, vegetation maps and land use maps.

7.4.2 Reviewed information includes, but is not limited to the following:

· EIA reports in the area including but not limited to AEIAR-220/2019 Yuen Long Effluent Polishing Plant; AEIAR-223/2020 Improvement of Yuen Long Town Nullah (Town Centre Section);

· Hong Kong Biodiversity – Newsletter of Agriculture, Fisheries and Conservation Department (AFCD);

· Publications of AFCD;

· Development Permission Areas Plan, Draft Outline Zoning Plans and Outline Zoning Plans of Town Planning Board;

· Annual report and other publications of The Hong Kong Bird Watching Society;

· Memoirs of Hong Kong Natural History Society; and

· Porcupine! Newsletter of Ecology & Biodiversity, The School of Biological Sciences, The University of Hong Kong.

Ecological survey methodology

7.4.3 In accordance with the requirements of the EIA Study Brief, necessary field surveys of at least 12 months covering both dry and wet season were required. Under the present EIA study, a 13-month ecological survey programme was completed to verify the information from the desktop review, fill the information gap in particular the Project Site and nearby habitats, and fulfil the objectives of this EIA. The survey was carried out by qualified personnel and the detailed methodology and findings of the ecological review is presented in Appendix 7.1.

7.4.4 Ecological survey items included the followings:

· Habitat and vegetation;

· Terrestrial mammal including night survey and camera trapping;

· Avifauna including night survey and flight behavior of waterbirds;

· Egretry;

· Herpetofauna;

· Butterfly and odonate;

· Firefly and;

· Aquatic assemblage; and

· Intertidal/benthic.

7.4.5 The ecological survey programme is listed in Table 7.1.

Table 7.1. Ecological Survey Programme from July 2019 to July 2020

Ecological Field Surveys	2019						2020
	Wet Season				Dry Season					Wet Season
	Jul	Aug	Sep	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Jun	Jul
Habitat and Vegetation Survey		✓	✓						✓
Terrestrial Mammal Survey	✓		✓		✓		✓		✓		✓
Terrestrial Mammal Survey (Nighttime)	✓		✓		✓		✓		✓		✓
Infra-red Camera Surveys for Eurasian Otters	Carried out continuously throughout the 12-month survey period
Avifauna Transect Survey	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Avifauna Transect Survey (Nighttime)	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Survey of Ardeid Night Roost at KTR	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Survey of flight behaviour of waterbirds	✓^#	✓^#	✓	✓	✓^*	✓^*	✓^*	✓^*	✓	✓^#	✓^#	✓
Egretry Survey										✓	✓	✓	✓
Herpetofauna Survey	✓	✓	✓		✓				✓		✓
Herpetofauna Survey (Nighttime)	✓	✓	✓		✓				✓		✓
Butterflies and Odonates Survey	✓	✓	✓		✓				✓		✓
Fireflies	✓	✓	✓							✓	✓	✓
Aquatic Assemblages Survey^			✓						✓
Intertidal / Benthic Survey			✓						✓

* Additional survey of flight behaviour of roosting waterbirds in winter

# Additional survey of flight behaviour of ardeids during breeding season

^ As a fish species Gobiopterus macrolepis of conservation importance was recorded during the survey, additional sampling locations were added

7.5 Baseline Condition

7.5.1 The baseline conditions of the ecological resources of the habitats in the assessment area are reviewed by desktop literature review and dedicated field surveys.

7.5.2 In summary, part of the Project Site (mainly at the last section of Yuen Long Nullah (YLN) where the barrage is proposed and the northern end of the proposed parapet wall at Kam Tin River drainage channel) is within WBA, while the remaining portions of Project Site do not fall within any recognised sites of conservation importance. Other recognized sites within the 500m assessment area include Wetland Conservation Area, Conservation Area under OZP, Priority Sites for Enhanced Conservation and Tung Shing Lei Egretry. While Mai Po Inner Deep Bay Ramsar Site, Mai Po Nature Reserve, and Mai Po Site of Special Scientific Interest are far away from the 500m assessment area.

7.5.3 Findings of the literature review (Appendix 7.1) identified a number of habitats and species of conservation importance recorded within and surrounding of the Project Site. Detailed findings of the field surveys are presented in Appendix 7.1.

7.5.4 The field surveys confirmed that the Project Site (components of proposed barrage, parapet walls and the revitalized section) lies mainly on channelized watercourse, plantation and developed area, with low to middle, low and very low ecological value, respectively. The ecological values of the wetland associated habitats within the 500m assessment area including channelized watercourse (only YLN Section 4, SPR, KTR), semi-natural watercourse, pond, abandoned wet agricultural land/freshwater marsh, tidal marsh, mangrove, reedbed and mitigation wetland are at least low to middle, middle or middle to high.

7.5.5 The ecological values of the habitats recorded within the 500m assessment area have been evaluated in accordance with the criteria stipulated in Table 2 of Annex 8 of EIAO-TM. Details of the evaluation are provided in Appendix 7.1. the overall ecological values of the habitats recorded in the 500m assessment area are summarized in Table 7.2.

Table 7.2 Habitat Evaluation

Habitat	Overall Ecological Value	Habitat found in Project Site?
Channelized watercourse	Very low: YLN Sections 1,2,3 and other minor channelized watercourses; Low: upper section of Yuen Long Bypass Floodway (YLBF) and Sham Chung River (SCR); Low to Middle: YLN Section 4, lower section of YLBF; Middle: SPR and KTR	Yes, revitalization will be conducted in YLN Sections 1-4, the proposed barrage will be in YLN Section 4
Semi-natural watercourse	Middle	No
Pond	Low to Middle: other ponds within the 500m assessment area; Middle: abandoned ponds within Nam Sang Wai (NSW)	No
Tidal marsh	Middle	No
Mangrove	Middle	No
Reedbed	Middle to High	No
Abandoned wet agricultural land / freshwater marsh	Low to Middle	No
Mitigation wetland	Middle	No
Shrubland	Low to middle	No
Agricultural land	Very low	No
Mixed woodland	Low	No
Plantation	Low: Remaining plantation within the 500m assessment area; Low to middle: plantation in NSW; Middle: for the locations that hold TSL egretry and night roost of ardeids	Yes, the pumping station and E&M room will be on the remaining plantation within the 500m assessment area, but no impact and far away from egretry or night roost.
Wasteland	Very low	No
Developed area	Very low	Yes, most of the proposed parapet walls will be on developed area

7.5.6 Species of flora and fauna with conservation importance were given special attention. A total of 2 flora, 3 mammals, 51 avifauna, 5 herpetofauna, 9 butterflies, 3 odonates, 1 aquatic fauna and the endemic Bent-winged Firefly, of conservation importance were recorded in the 500m assessment area. Among the species of conservation importance, a total of 14 species of birds of very low abundance and a fish species of conservation importance were recorded inside the Project Site. Detailed evaluation of the species of conservation importance is shown in Appendix 7.1.

7.6 Identification of Ecological Impacts

Identification of Key Works

7.6.1 The proposed works of the present Project will include three major components (1. proposed barrage, 2. parapet walls, and 3. revitalization): provision of a barrage at the northern end of Yuen Long Nullah, the modification of parapet wall along a section of Kam Tin River, and the provision of parapet wall along a section of Yuen Long Nullah to the south of Yuen Long Highway, and a section of Sham Chung River (the existing railing (~1m) in the section of YLN and Sham Chung River will be replaced by parapet walls of ~1m high). The location plan of the three major components is shown in Drawing No. 400171/B&V/LAY/001 in Appendix 1.1.

7.6.2 Construction of the barrage generally involves common civil engineering construction activities such as site clearance, excavation, formwork, substructure and superstructure construction, concreting, landscaping and E&M installation. The proposed works for the barrage shall comprise of 3 phases: Phase 1 – channel deepening, widening and stabilization works (cofferdam for temporary diversion, excavation works by open cut, slope stabilizing (concreting works)); Phase 2 – construction of pumping stations, E&M control room and link bridge (cofferdam for temporary diversion, foundation works (percussive piling / concreting works), superstructure and E&M installation works); Phase 3 – tidal barrier assembly and installation (cofferdam for temporary diversion, flow optimising walls in YLN, superstructure and E&M installation works).

7.6.3 Additional concrete parapet walls would be constructed along YLN and Sham Chung River along sections that are vulnerable to flooding. The existing parapet walls along Kam Tin River would be heightened with opaque panels.

7.6.4 Upon completion of the barrage, revitalization works along YLN will be conducted. The revitalization works of YLN will involve smaller scale construction activities such as breaking of concrete nullah bed, excavation, decommissioning of existing low flow pumping station and inflatable dam, construction of hard landscapes (concreting works) and installation of greenery (planting).

Construction Phase – Direct Impacts

Habitat loss

7.6.5 The proposed barrage scheme involves construction of a barrage in the lower section of YLN (YLN Section 4), the proposed pumping stations and E&M control room will be constructed beside the barrage on the Nullah as well as adjacent plantation (Figure 7.1). New and heightening of parapet walls will be constructed in upper YLN (YLN Section 1) as well as Sham Chung River and Kam Tin River, respectively.

7.6.6 Parapet walls – The new and heightening of parapet walls will be of simple structures, in linear shape, and situated above existing concrete parapet walls or replacing existing hand rail. They will occupy limited area size on developed area which are of very low ecological values, and will not change the nature of the existing habitat after construction and thus is not expected to cause habitat loss. Although a tiny part of the heightened parapet in Kam Tin River is situated within the WBA, all construction works for the heightened parapet walls will be confined to land areas to avoid direct impacts on wetland (i.e. channelized watercourse). A night roost of ardeids was recorded next to Kam Tin River which is just next to the proposed parapet wall. However, the trees of the ardeids’ night roost will not be encroached or affected by the works. Hence, the direct ecological impact due to the proposed parapet walls are minimal and habitat loss is not expected.

7.6.7 Proposed barrage –The construction of the proposed barrage, pumping stations and E&M control room will result in small direct loss of habitats in plantation and channelized watercourse (YLN Section 4) which are of low and low to middle ecological values, respectively and are located at the fringe of WBA. A total 0.29ha of plantation will be encroached due to the area occupied by pumping station (0.10ha) and E&M room (0.09ha), and the space released for channel widening works (0.10ha). As the plantation was dominated by exotic plant species and without any species of conservation importance recorded (different from the plantation in NSW of which ecological value is comparatively higher (see Table 30 of Appendix 7.1), the direct impact due to the loss of small area of plantation is considered minor. Compensatory planting will be proposed under LVIA.

7.6.8 The affected channelized watercourse (YLN Section 4) is the northern end of YLN. Similar with other upstream sections, this section still has concrete-lined banks and bottom, but the concrete channel bed has been deposited with mud sediments originated from the Deep Bay area. YLN Section 4 up to the location of existing inflatable dam currently receives brackish waters from Deep Bay. When the deposited sediments are exposed and waterbirds may be present in the channel. There were records of wetland-dependent bird species in YLN Section 4 and some of them are considered as species of conservation importance, but both bird diversity and abundance were much lower than the nearby SPR and KTR. In fact, the construction of the proposed barrage system in YLN Section 4 will directly encroach about 1.02ha of channelized watercourse (i.e. 0.26ha for the footprint of tidal barrier and pumping station which will constitute permanent loss; 0.76ha of the watercourse will be deepened and widened which will constitute temporary loss), the direct encroachment of the habitat (i.e. 1.02ha of watercourse during construction phase) will be very limited. On the other hand, the existing inflatable dam with an area of approximately 255m² will be decommissioned, so that some area (i.e. 255m²) of waterbody will be re-provided. In addition, the operation of the future tidal barrier can still allow water from the Deep Bay flushing in, and reach beyond the existing inflatable dam location (when without the obstruction of the inflatable dam). It is estimated that about 50m stretch of YLN upstream of the inflatable dam can provide additional ~0.26ha of wetland habitat, of similar size to those occupied by the barrage, and achieve no net loss of wetland.

7.6.9 During construction of the barrage, the proposed works will be conducted in phases and the channelized watercourse within the footprint will be temporarily isolated for works part by part (possibly finish the construction of one side and then the other side). The watercourse would not be blocked at any given time, and will allow brackish waters flushing into the YLN Section 4 outside the barrage works areas. Hence, the brackish water habitat (i.e. in between the existing inflatable dam and the proposed barrage) will only be lost partially during construction, plus minor additional area of plantation and watercourse which will be lost temporarily due to the works space and the cofferdam. Due to the small area size (when compared to similar habitats within Deep Bay) and nature (i.e. man-made structure) of wetland habitat, availability of similar habitats nearby, the direct impact of temporary habitat loss due to the construction of the proposed barrage is considered minor to moderate.

7.6.10 Revitalization – The revitalization works in YLN aims for improvement of the environment and enhancement of the ecological functions, and might involve demolition of the existing channel bed. Direct impacts are expected. Although few bird species of conservation importance were recorded in YLN Sections 1 to 3, the abundance were very low. Together with the naturalness and environmental settings, the ecological values are ranked as very low. Hence, the potential ecological impacts due to the revitalization works for YLN Sections 1-3 are considered minor. For YLN Section 4, the existing concrete nullah bed will be removed, deepened and filled with natural substrate. Currently the part downstream to the existing inflatable dam within this section had records of a number of wetland-dependent bird species and some of them are considered as species of conservation importance, while the part upstream to the inflatable dam is mostly dry with the bare concrete bed exposed, similar with YLN Sections 1-3. The revitalization works will be conducted after the construction of the barrage. Similarly, the revitalization works will also be conducted part by part, in particular within YLN Section 4, and the flow will be maintained at any given time. It is considered that the temporarily habitat loss caused by the revitalization works in YLN Section 4 will be of similar magnitude with that due to the construction of the barrage discussed above, the potential ecological impacts on YLN Section 4 are considered minor to moderate. It is expected that the ecological values will be increased due to the revitalization, in particular YLN Section 4 with the theme of ecological enhancement. While the decommissioning of existing low flow pumping station and inflatable dam will release the land space as well as the channel area, turning developed area habitats into channelized watercourse, and thus direct impacts to ecology is minimal and no habitat loss is anticipated.

7.6.11 Estimated loss of area of each habitat type is summarized in Table 7.3.

Table 7.3 – Estimated Loss of Area of Each Habitat Type

Habitat	Works	Temporary Loss (ha)	Permanent Loss (ha)
Developed Area	Revitalization	6.94	0
Plantation	Barrage scheme	0.29 (channel widening works: 0.10; pumping station: 0.10; E&M room: 0.09)	0.29
Channelized watercourse (brackish water habitat)	Barrage scheme	1.02 (tidal barrier: 0.09; pumping station: 0.17; channel deepening and widening: 0.76)	0 (although 0.26ha of watercourse due to tidal barrier and pumping station will be lost permanently, the replacement of existing inflatable dam with the operation of tidal barrier will allow waters from Deep Bay flush in 50m beyond the existing inflatable dam to achieve no net loss of wetland)
	Revitalization	13.64	0
	Total	21.89	0.29

Fragmentation

7.6.12 Fragmentation is the appearance of discontinuities in habitat that render it less attractive to flora or fauna or isolate populations of a species, potentially leading to reduced viability of a population. In the current study, potential fragmentation impacts to major channelized watercourses include additional barriers to the movement of aquatic life especially the proposed barrage. The flight path of waterbirds might also be affected by both the proposed parapet walls and barrage.

7.6.13 Water connectivity – As YLN Section 4 receives brackish waters from the Deep Bay during high tide, aquatic life follow tidal influence might be blocked by the construction works of the proposed barrage. The ecological value of YLN Section 4 is considered low to middle with low diversity and abundance of aquatic fauna. The ecological value of this section of channelized watercourse is mainly due to the presence of waterbirds. Although the diversity and abundance of aquatic fauna were low, a fish species of conservation importance Gobiopterus macrolepis was found along channel margins at YLN Section 4. In an extreme case, fragmentation impacts may result in the loss of populations of a species if the remaining fragments are too small to support a viable population. Species mostly affected by fragmentation impacts are usually habitat specialists, terrestrial species and species with low mobility. In order to maintain the connectivity during construction phase, the pumping stations and tidal barriers will not be constructed simultaneously (i.e. will be by 2 sections, one of the pumping station and half of the tidal barrier at a time). Hence, the channelized watercourse will not be completely blocked and allow brackish waters flush in and out YLN Section 4 during high tide and low tide, respectively, as in the existing situation. The water body between the proposed tidal barrier and the existing inflatable dam will be maintained except the ongoing works area for the pumping station and tidal barrier. The completed part of the tidal barrier will be opened to allow water to flush in, and another works area will be demarcated for construction of the remaining part of barrier. On the other hand, a cofferdam will be constructed to divert the water from upstream to downstream of the channel. Hence, the ecological impact to aquatic fauna due to fragmentation during construction phase is considered minor.

7.6.14 Flight-line of waterbirds – Flight-line impacts are another type of fragmentation impact that affect flying fauna. Typical flight-lines involve routes followed between feeding and roosting areas or between feeding and breeding areas. Development located on a flight-line may result in a decrease in the suitability of a foraging, breeding or roosting site by preventing movement between sites. In an extreme case, this may lead to the total abandonment of one or both sites. There may also be an increased risk of mortality by collision with structures constructed on or close to a flight-line.

7.6.15 The proposed parapet walls and barrage might potentially have fragmentation impact on flight-lines of ardeids or other waterbirds (e.g. Great Cormorant). As there are existing parapet walls along Kam Tin River and only heightening of ~200mm is proposed (i.e. from existing 1m to 1.2m), and in accordance with ecological survey results, the recorded flight heights of waterbirds including ardeids and Great Cormorant passing through the location of the proposed parapet walls in Kam Tin River were all above 10m, potential impacts to waterbird flight-lines due to the heightening of parapet walls are not expected. While additional concrete parapet walls will be constructed along YLN and Sham Chung River along sections that are vulnerable to flooding, but those sections are already with metal railing (~1m high) which will be replaced by concrete parapet wall of the same height. Besides, the areas are surrounded by developed area and, the abundance and diversity of waterbirds were very low, the potential impacts due to fragmentation of the proposed parapet walls in YLN and Sham Chung River are also not expected.

7.6.16 On the other hand, the height of the proposed barrage varies from 6 – 19 mPD (tidal barrier: 0-6 mPD; link bridge: 7.2 mPD; pumping station: 19 mPD; E&M building 13.6 mPD), and a portion of waterbird’s flight-lines (347 observations from 36 survey sessions (30min per session) during a 12-month period, approximately less than 10 birds per survey) flied along the YLN Section 4 across the proposed barrage location with the height below 10m, among other waterbird flight-lines above 10m and even higher than 20m reported from the same surveys. This indicated that the flight behaviour of some water birds currently flying along the YLN will be affected. Due to the artificial nature and disturbance level in YLN, major feeding and roosting grounds in the upstream of YLN (i.e. YLN Sections 1 to 3) are not anticipated. In fact, the abundance of waterbirds recorded in YLN Section 4 was much lower when compared with the abundance recorded in Shan Pui River and Kam Tin River from the current study, and also the abundance in Deep Bay Area according to the Monthly Waterbird Monitoring conducted by Hong Kong Bird Watching Society (Table 7.4). Besides, various flight heights of the ardeids as well as other waterbirds were observed including those fly over infrastructures of certain height such as highways. For example, the breeding ardeids in Tung Shing Lei Egretry flied over Tsing Long Highway were all well over 10m in height (the Highway is about 20m in height). And as mentioned above the recorded flight heights of waterbirds passing through the location of the proposed parapet walls in Kam Tin River were also all above 10m. With the future barrage in place, the change of flight height of waterbirds would be limited as the tidal barrier and link bridge will be around 6 and 7.2mPD, respectively. Hence, the potential fragmentation impacts to ardeids and other waterbirds from the proposed barrage are considered minor due to the low abundance, manoeuvrability of waterbirds and the unlikely feeding and roosting grounds in the upstream of YLN.

7.6.17 According to the ecological baseline survey, the breeding ardeids at Tung Shing Lei egretry mainly flying a general northward direction with occasional individuals landing at the ponds in front of the egretry or flying western to Yuen Long Town direction. Hence, the potential impacts to the flightpath of breeding ardeids at the egretry are not expected. Besides, a new egretry at Shan Pui River (i.e. Shan Pui River Egretry) was newly found at and near the Yuen Long Sewage Treatment Plant. Potential impacts to the breeding ardeids from the new egretry are not expected, as no breeding ardeids were observed flying from that egretry towards the Project Site. In addition, as it is over 1 km from the Project Site and there are abundant suitable wetland habitats near the egretry, in particular to the north of the egretry.

Table 7.4 Comparison of Waterbirds’ Abundance among the Assessment Area, Nam Sang Wai, Shan Pui River and Deep Bay Area during the Ecological Survey Period

	Current Study		Monthly Waterbird Monitoring Conducted by HKBWS**
	Shan Pui River	YLN Section 4	Shan Pui River***	Nam Sang Wai	Deep Bay Area
Species no.*	25	16	33	39	91
Total abundance (during the monitoring period)*	1,143	228	3,373	22,847	201,194
Average per month (abundance)	98	23	375	2,539	22,355

*Species no. and total abundance of the monthly waterbird monitoring were from Jul 2019 to Mar 2020 (versus Jul 2019 to Jun 2020 from current study)

**Mai Po Inner Deep Bay Ramsar Site Waterbird Monitoring Programme 2019-20 Biannual Report 1 (April to September 2019) p.35-43; Mai Po Inner Deep Bay Ramsar Site Waterbird Monitoring Programme 2019-20 Monthly Waterbird Monitoring Biannual Report 2 (October 2019 to March 2020) p.31-48

***Shan Pui River from monthly waterbird monitoring refers to lower course of Shan Pui River where is not overlapped with the surveyed section from current study

Construction Phase – Indirect Impacts

Water quality

7.6.18 During the construction phase, aquatic and the intertidal habitats (e.g. tidal marsh, mangrove) near the proposed works including construction of barrage, decommissioning of existing low flow pumping station and inflatable dam and revitalization would be potentially impacted by surface runoff, especially during rainstorm. The surface runoff might be polluted by sedimentation from site surfaces; excavation and backfilling works, wash water from dust suppression sprays and wheel washing facilities, concrete spillage, and chemicals spillage such as fuel, oil, solvents and lubricants from maintenance of construction machinery and equipment.

7.6.19 Elevated suspended solid levels caused by site runoff could increase the suspended solids load in the water bodies, and could decrease dissolved oxygen levels. A lower oxygen level would affect stationary species, whilst mobile species would tend to temporarily avoid the area. The result could be a temporary reduction in aquatic life abundance and/or change in distribution. Shan Pui River, tidal marsh and mangrove are downstream to the proposed works, all with middle ecological values, and supported a fish species of conservation importance (i.e. Gobiopterus macrolepis). If without control, the potential impact due to runoff to these habitats is considered moderate.

7.6.20 Guidelines in DSD Practice Note No. 1/2015 and ETWB TCW No. 5/2005 set out for the protection of natural rivers and streams from adverse impacts arising from construction works should be followed.

7.6.21 Precast structures or other similar approaches should be used to minimize construction works inside the watercourse and thus reduce direct water quality impact to Shan Pui River and Old Kam Tin River. Good site management as stipulated in ProPECC PN1/94 should be fully implemented to avoid polluted liquid or solid wastes from falling into the river waters. The potential of these impacts will be greatly reduced to acceptable level.

7.6.22 Besides, excavation works within the watercourse might release contaminants to the aquatic habitats, which subsequently affecting aquatic life. According to Chapter 5, the use of containment structures and diversion channels is recommended wherever practicable to facilitate a dry or at least confined excavation within the nullah. Water within the contained area should be discharged to the nullah before excavation commences to create a dry condition. Besides, careful programming of the works to avoid excavation works during the rainy season is recommended in Chapter 5 that can further minimize the chance of releasing contaminants to aquatic habitats. Hence, the potential ecological impacts to downstream to the works area including the confluence of Shan Pui River and Kam Tin River, and Deep Bay area from the excavation works are considered minor.

Construction noise disturbance

7.6.23 The potential response of waterbirds to noise disturbance varies from minor response like head turning scanning to behavioural changes like taking flight, reducing feeding/roosting time or increasing agonistic behaviour, depending on the sensitivity of the waterbirds and the level of disturbance. In general, high level of disturbance could cause deterioration of habitat quality and decrease of bird usage as well as subsequent decrease in wildlife density of the sensitive wetland habitats in the vicinity of the works area. Hence, the birds might move away to areas which are less disturbed and within their noise tolerances or reduce the foraging efficiency of birds that remain in the affected area. While the sensitivity of waterbirds to the same level of noise disturbance varies among different species, residents are typically more tolerant of disturbance than migrant birds (Klein et al. 1995). As such, the noise disturbance from construction activities of this Project on waterbirds that are present all year round (e.g. resident ardeids) are expected to be less significant than the disturbance impacts on migratory/overwintering waterbirds given the generally higher tolerance of residents to disturbance. While in many instances higher level of stimuli from construction works, e.g. construction noise, would cause greater level of disturbance, waterbirds were found to be especially prone to the intrusion of human activities into the wetland habitats and high level of irregular construction noise (Cutts et al. 2008 & 2013).

7.6.24 Among different noise source from various construction activities, noise from foundation works would generate higher construction noise. Various construction methods for foundation works, including the conventional percussive piles, bored piles by reverse circulation drill, box rafts and shallow foundation, have been explored for this Project. The foundation options are highly subject to the ground conditions. While box rafts, bored piling by reverse circulation drill and shallow foundation typically cause less disturbances (including noise, vibration and dust etc.), the application of these methods for this Project is comparatively limited, given the site and engineering constraints, including deep bed rocks (over 150 m below ground) of the Project Site, additional ground treatment (e.g. grouting) required for foundation works and large excavation volume, that could cause other environmental issues such as water pollution and adverse waste management implication. Due to the ground conditions and programme constraints, percussive piling works might be a more feasible foundation method. It is noted that alternative piling method will be considered as far as practicable during the detail design. In the case percussive piling is unavoidable, it will generate higher construction noise levels as compared to other general construction activities of the Project, including site clearance/formation, superstructure or other quieter demolition/foundation methods. In general, construction noise of above background noise level is likely to cause low to moderate level of disturbance that would trigger some degree of responses, which could be readily habituated, in waterbirds (Cutts et al. 2008 & 2013).

7.6.25 It is noticed that there is no established criteria/threshold for construction noise tolerance of waterbirds in Hong Kong or similar urbanized environment, the unmitigated construction noise levels at most of the noise assessment points are predicted to exceed relevant noise control standards for domestic premises stipulated under the Annex 5 of EIAO-TM (see Chapter 4) during the construction phase in the absence of mitigation measures. This degree of construction noise levels could potentially cause moderate level of disturbance to the waterbirds. Hence, mitigation measures for noise reduction will be required and stated in Chapter 4.

7.6.26 It is worth noting that during the wet season months, the key wetland habitats for waterbirds, as well as the wetland habitats nearby the Project Site were actually dominated by comparatively low abundance of disturbance-tolerant resident waterbirds that are common and present all year round (mainly resident ardeids). It should be noted that while wetland habitats comprise about 20% of the 500m assessment area, and there are about 1,500 ha of wetland in the Ramsar Site north to the 500m assessment area. Serious impacts to the waterbirds using the wetland habitats near the Project Site is therefore unlikely given the ability of birds to move away from sources of disturbance as well as the ample of well-connected, continuing and extensive wetland habitats available within and in the vicinity of the assessment area. Given the relatively higher diversity and abundance of overwintering waterbirds recorded in the Shan Pui River, the confluence of Shan Pui River and Kam Tin River, as well as Nam Sang Wai and the high construction noise level, the impact from construction noise disturbance is considered moderate for migratory/overwintering waterbirds and minor to moderate for the more tolerant waterbirds that are present all year if unmitigated.

Vibration disturbance from piling works

7.6.27 Among the piling methods, percussive piling would generate vibration disturbance. Apart from construction noise, ground-borne vibration due to percussive piling works at the Project Site could also disturb waterbirds foraging or resting in wetland habitats nearby the site. Higher diversity and abundance were recorded at lower Shan Pui River and at the confluence of Shan Pui River and Kam Tin River, which are away from the proposed works area, so that the vibration impacts to the waterbirds at those areas are not anticipated. While wetland habitats located in close vicinity from the Project Site supported significantly less diversity and abundance of waterbirds that were mostly resident, the impact from the vibration due to percussive piling works for migratory/overwintering waterbirds is therefore considered minor to moderate for migratory/overwintering waterbirds and minor for more tolerant waterbirds that are present all year if unmitigated.

Dust and human activities

7.6.28 Dust and human activities will increase during construction phase, and might temporarily reduce the abundance and distribution of fauna in habitats adjacent to the works area.

7.6.29 Apart from construction noise, disturbance to waterbirds caused by construction and decommission activities could have been largely attributed to the increased presence of people/visual stimuli associated with such activities such as movement of plants or workers operating outside of machinery (Cutts et al., 2008 & 2013). Due to the alignment of Shan Pui River (i.e. curved towards northwest side after the location of proposed barrage), waterbirds in the Shan Pui River away from the proposed barrage would not be affected by the human activities during construction phase, as the view is blocked by the eastern side of Yuen Long Industrial Estate. Besides, the wetlands in Nam Sang Wai are also mostly blocked by plantation. The impacts of disturbance due to increased human activities to waterbirds in particular Shan Pui River as well as the confluence of Shan Pui River and Kam Tin River and Nam Sang Wai are considered minor. Nonetheless, given the short separation distance between the Project Site and Shan Pui River/Nam Sang Wai, implementation of good site practices would still be recommended to further minimise the construction/visual disturbance on the waterbirds using the Shan Pui River and Old Kam Tin River as much as possible.

7.6.30 Dust generated during the construction phase (e.g. construction machinery, improper storage or dumping of construction materials) could degrade the habitats adjacent to works area. Construction dust could cover the leaves of plants in adjacent habitats and may affect photosynthesis, respiration and transpiration of the plant and allow the penetration of phytotoxic gaseous pollutants, thus changing the vegetation structure and/or reducing the quality of habitat (Farmer, 1993). With the implementation of mitigation measures and good site practices to minimise the potential dust impact during the construction phase, no adverse air quality impact due to the proposed works is anticipated. The impacts of construction dust disturbance on terrestrial and wetland habitats, vegetation and other associated fauna are therefore considered minor.

Artificial Lighting/Glare

7.6.31 Artificial lighting/glare could also affect light sensitive wildlife including the endemic Bent-winged Firefly, the ardeid night roost next to Kam Tin River, the Great Cormorant roosting on trees in Nam Sang Wai and the mammal species of conservation importance. The artificial lighting/glare could attract, disorient or disrupt the light-sensitive cycle of the light sensitive/nocturnal species, subsequently affecting their migration, foraging/predation and breeding success and causing the reduction of faunal density in the area. However, given that the construction hours would be from 07:00 to 19:00 that no night-time construction works would be required under this Project, working lights might only be turned on during evening time or cloudy days with low light intensity. In any cases, there will be no working lights after 19:00. Due to the sensitivity of nocturnal animals, the impacts of construction lighting/glare disturbance are considered minor to moderate. In light of the presence of light-sensitive fauna species of conservation importance in the vicinity of the Project Site, implementation of good site practices would be recommended to minimise the impacts of the artificial lighting/glare as much as possible.

Disturbance to ardeid night roost

7.6.32 While there are no night-time works under this Project and the impacts of construction lighting/glare disturbance are considered minor for light-sensitive fauna species of conservation importance in the vicinity of the Project Site, ardeids habitually return to the night roost at every evening at around an hour before sunset and the construction activities (construction hours: 07:00 to 19:00) would potentially briefly interfere with the nigh roosts for up to around 2 hours and cause disturbance impacts (mainly construction noise) on the ardeids night roost beside the proposed parapet wall at Kam Tin River. The roosting ardeid could potentially relocate to another nearby location for roosting or other site along Kam Tin River. Nonetheless, a change in night roosting site is unlikely to trigger a decline in population as their breeding/nursery site are not affected (MTRC, 2010). Furthermore, ardeid night roosts are known for their highly changeable locations and roosting population that the roosting location can be in temporal basis and even change from day to day on a small scale. It has been observed in multiple cases in Hong Kong that the night roosting sites were rather unstable and the change in their location could happen naturally. The fluctuation of roosting population, abandonment or change in locations of roosting site without major nearby environmental change has been observed in roosts of various scale (from less than 100 to near 2,000 ardeids) and locations in Hong Kong (HKJC, 2005; Lee et al., 2004; MTRC, 2010). Given that ardeids are generally more tolerant to disturbances and short interface of the construction hours and ardeids roosting hours, the unmitigated impacts from the construction noise disturbance are expected to be minor to moderate on the ardeid night roost given the short separation distance. Mitigation measures and good site practices should also be implemented to minimise the impacts of construction/visual disturbance on the ardeid night roost beside Kam Tin River as much as possible.

Construction Phase – Impacts on recognized sites, important habitats and species of conservation importance

Recognized sites of conservation importance and important habitats

7.6.33 Most of the recognized sites of conservation importance were outside the Project Site, only part of the Project Site (mainly at the last section of YLN where the barrage is proposed and the northern end of the proposed parapet wall at Kam Tin River drainage channel) is within WBA. Other recognized sites within the 500m assessment area include Wetland Conservation Area, Conservation Area under OZP, Priority Sites for Enhanced Conservation and Tung Shing Lei Egretry will not be affected directly. While Mai Po Inner Deep Bay Ramsar Site, Mai Po Nature Reserve, and Mai Po Site of Special Scientific Interest are far away from the 500m assessment area, potential impacts are not anticipated.

7.6.34 Part of the Project Site falls within the WBA (a small area of channelized watercourse (YLN Section 4), plantation and developed area), while other recognized sites of conservation importance (e.g. Mai Po Inner Deep Bay Ramsar Site, Wetland Conservation Area, Mai Po Nature Reserve, SSSI, Conservation Area, Priority Site and Tung Shing Lei Egretry), and important habitats such as mudflat/mangrove at Kam Tin River and Shan Pui River will not be directly affected.

7.6.35 However, the wetland habitats including the mudflat/mangrove at Kam Tin River and Shan Pui River within the assessment area in particular Deep Bay area serve as important feeding/roosting ground for migratory and overwintering waterbirds, the indirect disturbance in particular noise could cause the deterioration of habitat quality and decrease of bird usage as well as subsequent decrease in wildlife density of the sensitive wetland habitats within the recognized sites of conservation importance in the vicinity of the works area. The sensitivity of the wetland habitats would generally be considered higher during the peak visiting period of the migratory and overwintering birds i.e. dry season given the greater number of species of conservation importance affected.

7.6.36 Amongst the wetland habitats within the assessment area, of particular note is the Shan Pui River and Nam Sang Wai located in the close proximity of the Project Site. The wetland habitats in these two areas supported a relatively greater diversity and abundance of migratory and overwintering waterbirds observed within the assessment area. The impacts of construction disturbance on the two areas are considered moderate during dry season and minor to moderate during wet season if unmitigated. Mitigation measures are detailed in the below section. Only minor works (construction of parapet walls) will be conducted in Kam Tin River, potential impacts to the wetland habitats in Kam Tin River are considered minor.

Species of conservation importance

7.6.37 As the plant species of conservation importance i.e. Aquilaria sinensis and Phymatodes longissimi were recorded away from the Project Site, no direct impacts to these two plant species are expected.

7.6.38 While the footprint of the tidal barrier and the works area will encroach the habitat of the fish species of conservation importance Gobiopterus macrolepis. However, the survey results of the present study revealed that this species occurred in different locations in the area, and the abundance of Gobiopterus macrolepis in YLN Section 4 was much lower than other occurrence locations such as the reedbed in Nam Shan Wai. However, due to the endemicity of Gobiopterus macrolepis, the ecological impact on Gobiopterus macrolepis due to habitat loss is considered minor to moderate. Mitigation measures for this species of conservation importance are required.

7.6.39 Bird species of conservation importance found within the Project Site in particular YLN Section 4 included Northern Shoveler, Chinese Pond Heron, Grey Heron, Great Egret, Little Egret, Great Cormorant, Black-winged Stilt, Pied Avocet, Little Ringed Plover, Pheasant-tailed Jacana, Common Redshank, Marsh Sandpiper and Common Greenshank. Besides, a regular high tide roost of Black-winged Stilt was found in YLN Section 4. Like the night roost of ardeids as discussed above, the roosting Black-winged Stilt could potentially relocate to another nearby location for roosting or other site along Shan Pui River. The roosting location for Black-winged Stilt might be affected temporarily. However, a change in night roosting site is unlikely to trigger a decline in population. To take a conservative approach, the whole section of YLN Section 4 will be lost temporary during construction phase, the ecological impacts are still considered minor to moderate, taken consideration of the habitat size and quality (some with concrete bed without sediment) as well as disturbance (regular maintenance dredging of the sediment in that section) when compared with the Deep Bay area.

7.6.40 The Nam Sang Wai area is an important roosting site for Great Cormorants. In winter, large roosting aggregations of Great Cormorants on the gum trees in the Nam Sang Wai fishpond area were often seen after feeding at Inner Deep Bay. No roosting Great Cormorant was recorded within the proposed works area, so that no direct impacts to roosting habitat of Great Cormorant are expected. While Black-faced Spoonbill was not recorded within the proposed works area and no roosting of Black-faced Spoonbill was also recorded within the 500m assessment area. Although Black-faced Spoonbill might feed within YLN Section 4, the potential direct impacts to this species are considered minor as the channel downstream to the YLN Section 4, i.e. Shan Pui River as well as the confluence of Shan Pui River and Kam Tin River provides suitable habitats for Black-faced Spoonbill.

7.6.41 While the indirect disturbance impacts of the construction activities (e.g. construction noise and increased in human activities), if unmitigated, might consequently cause the waterbirds to avoid using the habitats near the works area (including Black-faced Spoonbill and roosting Great Cormorant at Nam Sang Wai). However, due to the distance from the proposed works area to the confluence of Shan Pui River and Kam Tin River, and Deep Bay area, potential impacts to the waterbirds roosting and/ or feeding to that area are not expected.

7.6.42 No mammal species of conservation importance including Eurasian Otter were recorded within the Project Site. Eurasian Otter is a semi-aquatic mammal which forages in water and nest on land. Recent records have only been found in the Mai Po Inner Deep Bay Ramsar Site and nearby region. However, no Eurasian Otter was recorded within the 500m assessment area throughout the present ecological survey and data from AFCD. Wandering individual might be possible but the chance entering the Project Site especially YLN Section 4 would be very low due to the condition and disturbance of the channelized watercourse. As discussed, the pumping stations and tidal barriers will not be constructed simultaneously, and the completed part of tidal barrier will be kept open, hence, potential impacts from habitat loss and fragmentation on Eurasian Otter are considered minor.

7.6.43 As there will be no night works during construction phase, working lights might only be turned on during evening time or cloudy days with low light intensity. The working lights would be turned off after 19:00. Potential impacts of construction lighting/glare disturbance to the light-sensitive fauna including the endemic Bent-winged Firefly, the ardeid night roost next to Kam Tin River, the Great Cormorant roosting in Nam Sang Wai and the mammal species of conservation importance in the vicinity of the Project Site are considered minor to moderate. In light of the presence of light-sensitive fauna species of conservation importance, implementation of good site practices would be recommended to minimise the impacts of the artificial lighting/glare as much as possible.

7.6.44 The other species of conservation importance including the butterfly, dragonfly, reptile and amphibian recorded away from the Project Site will not be affected significantly.

Operational Phase – Direct Impacts

Habitat loss

7.6.45 Without the proposed barrage, the brackish water from Inner Deep Bay flushes into YLN Section 4 up to the existing inflatable dam during high tide period. The brackish water flushed from the Inner Deep Bay also brings sediment to YLN Section 4, that created an intertidal mudflat-liked habitat which attracts waterbirds to roost and feed during low tide. The fish species of conservation importance Gobiopterus macrolepis was also recorded in YLN Section 4, but the abundance was much lower than the reedbed in Nam Sang Wai.

7.6.46 According to Chapter 2, the operation of tidal barrier will be closed during high tide above 0.5mPD and will be opened below 0.5mPD (Appendix 2.5). Currently water from Deep Bay starts flushing in at about ~0.2mPD during flooding tide. Hence, the water with sediment from Deep Bay can still be flushed into YLN Section 4 from ~0.2-0.5mPD during flooding tide before closure of tidal barriers. As the whole section of YLN Section 4 will be deepened (either for barrage or for revitalization), a certain amount of the water from Deep Bay can be kept within the YLN Section 4 and will be maintained at a certain depth even the tidal barriers are closed. After the tidal barrier is closed, the waters from the Deep Bay can still be flushed into the YLN Section 4 during high tide through the proposed 300mm x 300mm ecological trench. Besides, the low flow pump can be operated when necessary to adjust a desired water level inside the YLN Section 4, and maintain water exchange even during closure of tidal barriers. The tidal barriers will then open again during the ebbing tide when the tidal level goes down to about 0.5 mPD, and the water kept within YLN Section 4 will go out to Deep Bay with the ebbing tide. The water in YLN Section 4 will thus be exchanged regularly, and the water depth within Section 4 will fluctuate between the level of about 0.5 mPD (when the tidal barrier is closed) and the depth of the deepening channel bed (when the water has gone with the ebbing tide). In practice, the water level in YLN Section 4 will be kept in a level which could facilitate the utilization of waterbirds for a longer time than its current condition.

7.6.47 The operation of the tidal barrier can still allow brackish waters with the sediment flush in and store in Section 4, so that the waterbirds can still utilize the Section 4 for roosting and feeding with a longer utilization time, and the Gobiopterus macrolepis can follow tidal influence and inhabit in YLN Section 4. Detailed operation of the tidal barrier and the low flow pump with the consideration of ecology (including the area size to be flooded by water, the water level and allowing sediment to enter YLN Section 4) will be confirmed in the Detailed Design Stage. The feasibility of flexible trigger levels and an adaptive management approach to extend the durations in partial opening of tidal barriers and operation of the low flow pumps could also be further explored. Extension of opening time of the gates will be considered if the water quality in Deep Bay has improved and there is no further odour concern for Yuen Long Town Centre and adjacent villages. For the footprint of tidal barrier and pumping station (0.26ha of watercourse) that will be lost permanently, the direct encroachment of the habitat as well as the feeding/roosting ground for waterbirds will be very limited. As discussed in the construction phase, the existing inflatable dam with an area of approximately 255m² will be decommissioned, so that some area (i.e. 255m²) of waterbody will be re-provided. Besides, the operation of the tidal barrier will allow water from the Deep Bay flushing in beyond the existing inflatable dam. It is estimated that about 50m stretch of YLN upstream of the inflatable dam can provide additional ~0.26ha of wetland habitat during operational phase, and hence achieve no net loss of wetland.

Fragmentation

7.6.48 The connectivity between YLN Section 4 and Shan Pui River might be blocked by the proposed barrage. As same as the construction phase, aquatic life and the fish species of conservation importance Gobiopterus macrolepis might be affected. With the operation of the tidal barrier and the 300mm x 300mm ecological trench that allow brackish waters flush into YLN Section 4 during high tide, the potential impacts to aquatic fauna as well as the Gobiopterus macrolepis are considered minor, while the existing inflatable dam will be decommissioned to re-provide connectivity to further upstream sections.

7.6.49 On the other hand, as discussed in the construction phase impact, the height of the proposed barrage varies from 6 mPD to 19 mPD. Only low numbers of waterbirds (about less than 10 birds per survey) flied along the YLN Section 4 with observed flight height below 10m.

7.6.50 Potential impacts to the flight-lines might occur. As discussed in the construction phase impact, the flight height of the waterbirds can be adjusted to fly over infrastructures such as highways. Besides, due to the artificial nature and disturbance level in YLN, major feeding and roosting grounds in the upstream of YLN (i.e. YLN Sections 1 to 3) are not anticipated. The abundance of ardeids and other waterbirds were very small compared to the abundance in Deep Bay Area (see Table 7.4). Hence, the potential fragmentation impacts to ardeids (including the breeding ardeids from Tung Shing Lei egretry and the new egretry at and near the Yuen Long Sewage Treatment Works) and other waterbirds from the proposed barrage are considered minor due to the low abundance, manoeuvrability of waterbirds and the unlikely feeding and roosting grounds in the upstream of YLN.

7.6.51 As the proposed parapet walls will be built mostly on existing concrete structures or developed area with limited height (~1m or 1.2m), there will be no direct ecological impacts deduced from the proposed parapet walls during operational phase.

Operational Phase – Indirect Impacts

Water quality

7.6.52 Although the operation of the tidal barrier allows brackish waters flush into YLN Section 4, the salinity upstream to the barrage might be lowered as the time of brackish water entering the barrage will be decreased. Drastic changes of salinity would affect the composition of benthic organisms which eventually affects the food source of waterbirds. Since the operation of tidal barrier allows brackish waters enter the upstream of barrage, change of salinity that eventually affect the benthic composition will not be significant. In fact, due to the influence of the discharge from the Pearl River, the Inner Deep Bay area experiences fluctuating salinity which could range from 3.2 to 29.2 ppt. Shan Pui River nearby the Project Site would therefore be exposed to varying salinity of a range similar to the existing condition under the tidal influence that no adverse impacts on the aquatic communities or the associated waterbirds are anticipated. On the other hand, freshwater habitats also provide roosting and feeding habitats for waterbirds (e.g. egrets), drastic changes of waterbird community are not likely. When compare with the size of similar habitat in Deep Bay area, and the abundance of waterbirds as well as the bird species of conservation importance, the potential ecological impacts due to the change of salinity of the YLN Section 4 is considered insignificant.

7.6.53 On the other hand, as the freshwater from upstream of YLN will be intercepted by the proposed barrage, salinity in Shan Pui River might be increased. However, the freshwater will not be diverted away from the barrage, and the gates of the tidal barrier will be opened or the upstream waters will be pumped out just after the tidal barrier to maintain the water connectivity. Hence, the potential ecological impacts are similar to above paragraph and considered insignificant.

7.6.54 In fact, the water quality in YLN will be improved as the dry weather flow will be collected and diverted to Yuen Long Effluent Polishing Plant according to the EIA study of Improvement of Yuen Long Town Nullah (AEIAR 223/2020), so that the water quality of YLN Section as well as Shan Pui River will further be improved. Therefore, the quality of the habitats for waterbirds will be further enhanced.

Change of hydrodynamics

7.6.55 According to Chapter 2, the tidal level in Old Kam Tin River will not be changed significantly, due to the large waterbody of Deep Bay, as compared with the existing concrete-lined section (to be regulated by YLBS), no significant increase is anticipated to the design tide levels at the Old Kam Tin River as well as Shan Pui River from the implementation of tidal barriers. Hence, the periods of low tides and high tides would be similar to the existing conditions. Waterbirds rely on the exposed mudflat in Old Kam Tin River and Shan Pui River as well as the confluence of Shan Pui River and Kam Tin River, and Deep Bay area during low tides would not be affected. The potential impacts due to change of hydrodynamics are considered insignificant.

Sedimentation

7.6.56 Shan Pui River is a drainage channel, its channel bed is composed of soft muddy sediments deposited through tidal movement. The exposed sediments in Shan Pui River in particular the confluence of Shan Pui River and Kam Tin River during low tide form a tidal mudflat for waterbirds to feed and roost, as benthic community which is a major food source for waterbirds, can be established in the accumulated sediments/tidal mudflat. Hence, Shan Pui River in particular the lower course as well as the confluence of Shan Pui River and Kam Tin River are favourite feeding grounds of waterbirds during low tide periods. During the operational phase of the barrage scheme, the discharge of water might flush away the sediments on the channel bed, which might affect the area of sediment exposure for waterbirds. However, the volume of water being discharge would not be different with the proposed barrage, only the force and the pattern of water discharge will be different. Hence, the potential impacts from the discharge on the sedimentation pattern/tidal mudflat are considered low to moderate at the location just outside the proposed barrage. The detailed design should consider the orientation of the outlet and angle of discharge, to minimize significant changes to the existing sedimentation pattern / mudflats in Shan Pui River and Old Kam Tin River. While the impacts to the confluence of Shan Pui River and Kam Tin River, and Deep Bay area are considered insignificant due to the distance (>1.5km) from the proposed barrage.

7.6.57 The barrage will also reduce the tidal flushing at the downstream area. However, considered the long distance (~3km) from the estuary to the proposed barrage, the tidal movement at the barrage will be weak. Therefore, increase in sedimentation is expected to be minimal at the downstream of the proposed barrage. Potential ecological impacts such as change in feeding and/or roosting habitats/areas in particular the confluence of Shan Pui River and Kam Tin River for waterbirds are not expected.

Bird collision

7.6.58 Only opaque instead of transparent glass panels will be used for the parapet walls, potential risk of bird collision on the parapet walls is considered insignificant.

7.6.59 The use of large areas of reflective material on the outer surfaces of the buildings (i.e. pumping stations, E&M control room) would be avoided to minimize the risk of aerial collisions from birds. Hence, the ecological impacts arising from bird collision is considered minor. However, given the close proximity of Shan Pui River with relatively higher abundance and diversity of birds, environmental friendly design of the buildings would still be recommended to minimize the potential impacts as much as possible.

Artificial Lighting/Glare

7.6.60 The behavior and distribution of nocturnal wildlife may be affected by artificial lightings. Lighting sources (e.g., village houses, buildings of Yuen Long Industrial Estate) are already present within and near the Project Site. Fauna inhabiting in habitats near the Project Site have probably habituated to lightings. Sensitive species might not be present in these areas.

7.6.61 During operation phase, only security light with minimum light intensity will be turned on at night, no flush light will be required. Hence, no significant adverse impact to nocturnal fauna in nearby areas is anticipated. Potential impacts to fauna from this source are considered minor. As an enhancement measure, further minimize the impacts on nocturnal fauna will be considered during Detailed Design Stage.

Operational Phase – Impacts on recognized sites, important habitats and species of conservation importance

Recognized sites of conservation importance and important habitats

7.6.62 The Project Site is located within WBA and is near the WCA/Conservation Area. However, the proposed barrage will not affect the ecological integrity of the wetlands within WCA/Conservation Area or cause direct habitat loss in WCA/Conservation Area, only small area within WBA will be lost permanently and is considered insignificant. While the wetland habitats in WCA are separated by a channelized watercourse from the Project Site. The potential impacts to the recognized sites of conservation importance as well as the important habitats such as mudflat/mangrove at Kam Tin River and Shan Pui River, and the habitats in Nam Sang Wai are considered insignificant as the operational phase disturbance (e.g. noise, human disturbance) will be very limited.

Species of conservation importance

7.6.63 No significant increase of human activities is expected during the operational phase of the barrage. Human activities will mainly be occurred inside the pumping stations and the E&M control room. On the other hand, the external lighting system required for the barrage, pumping stations and the E&M control room is expected to be low and would not affect nearby wildlife and species of conservation importance, particular the night roost of Great Cormorant at Nam Sang Wai (though no night roost of Great Cormorant was identified within the 500m assessment area), light-sensitive endemic Bent-winged Firefly and the nocturnal mammal species of conservation importance. As lighting system is not necessary for the parapet walls, the ardeid night roost beside Kam Tin River will not be affected. The glare would be further minimized through landscape design and control of lighting system. Hence, disturbance impacts from the operation of the barrage, including human activities and lighting/glare to the ecological value of the nearby habitats and wildlife, particularly waterbirds and light-sensitive wildlife, as well as recognized sites of conservation importance, are considered minor. In light of the presence of light-sensitive fauna species of conservation importance in the vicinity of the Project Site, implementation of good site practices would still be recommended to further minimize the impacts of the artificial lighting/glare from the light system required at night as much as possible.

7.6.64 According to Chapter 2, approximately 2-12 hours of opening per day could be catered but subject to other parameters. Hence, the watercourse would not be blocked and allow semi-aquatic fauna such as Eurasian Otter to access the YLN Section 4. As mentioned in the construction phase, no Eurasian Otter was recorded in the assessment area by present study and AFCD, potential impacts to Eurasian Otter are considered minor. In order to cater wandering individual entering the Project Site, provision of a corridor should be considered to provide an access for Eurasian Otter between Shan Pui River and YLN Section 4.

7.6.65 After revitalization of YLN, in particular YLN Section 4, the ecological value will be enhanced. The enhanced habitat can provide more microhabitats for the waterbirds and the fish species of conservation importance i.e. Gobiopterus macrolepis. In addition, as the bank of YLN Section 4 provided a high tide roost for Black-winged Stilt, the bank will be kept or with limited enhancement. Hence, the high tide roost of Black-winged Stilt will be maintained/enhanced for the species. As the existing YLN Section 4 would be covered by waters during high tide, which is not a favourable roosting location for waterbirds. However, with the operation of the tidal barrier and the revitalization measures, the YLN Section 4 will provide a high tide roost for other waterbirds.

7.7 Potential for Cumulative Impacts

7.7.1 In order to assess the cumulative impacts, a review of best available information at the time of preparing this EcoIA to identify a number of other projects that are undergoing planning, design, construction and/or operation within the construction and /or operation period for this Study has been conducted. The potential occurrence of cumulative impacts would be mostly determined by the nature of the projects, the project scales, and the distance between the projects. The cumulative impacts were assessed based on Section 4.3.3 of the EIAO-TM.

7.7.2 According to the preliminary construction programme of the Project (Chapter 2), the construction works is anticipated to commence in Q4 of 2022 for completion by Q2 of 2027, with concurrent construction and modification of the parapet walls. Upon completion of the barrage, the revitalization works along YLN and decommissioning of the existing inflatable dam would take place unit Q3 of 2029.

7.7.3 Five concurrent projects are identified in the vicinity the Project Site as discussed in Chapter 2, including the “Improvement of Yuen Long Town Nullah (Town Centre Section) – Stage 1 Improvement Works – Design and Construction”, “Elevated Pedestrian Corridor in Yuen Long Town Connecting with Long Ping Station – Investigation, Design and Construction”, “Yuen Long Effluent Polishing Plant – Investigation, Design and Construction”, “Yuen Long South Development – Stage 1 – Design and Construction”, and “Hung Shui Kiu Effluent Polishing plant and Yuen Long South Effluent Polishing Plant – Investigation”. Table 7.5 summarizes the relevancy of the concurrent projects.

Table 7.5 Potential Cumulative Ecological Impact from Concurrent Projects

Concurrent Projects	Project Proponent	Construction Programme	Potential Cumulative Impacts
			Construction Phase	Operational Phase
Present Project	DSD	Q4 2022 to Q2 2027	N/A	N/A
Improvement of Yuen Long Town Nullah	DSD	Q2 2021 to 2026	Part of the proposed works area falls within the WBA, cumulative impacts from the works of rising mains are expected. As the construction works will be scheduled outside dry season, significant cumulative impacts to ecology and waterbirds are not expected.	Potential cumulative ecological impacts are not expected as there will be no high disturbance to the environment. On the other hand, the water quality in YLN as well as Shan Pui River will be enhanced.
Elevated Pedestrian Corridor in Yuen Long Town Connecting with Long Ping Station	HyD	2020 to 2025	No cumulative impacts are expected as the works are away from the present Project.	No cumulative impacts are expected as the works are away from the present Project.
Yuen Long Effluent Polishing Plant	DSD	2020 to 2030	Potential cumulative disturbance impacts to ecology and waterbirds are anticipated, as percussive piling works will be conducted for both Projects. However, the noise impacts to waterbirds will be mitigated, and percussive piling works will be scheduled outside the peak season of waterbirds.	Potential cumulative ecological impacts are not expected as there will be no high disturbance to the environment. On the other hand, the water quality in Yuen Long Nullah as well as Shan Pui River will be enhanced.
Yuen Long South Development	CEDD	2020 to 2038	No cumulative impacts are expected as the works are away from the present Project.	No cumulative impacts are expected as the works are away from the present Project.
Hung Shui Kiu Effluent Polishing plant and Yuen Long South Effluent Polishing Plant	DSD	Q1 2028 to Q4 2032	No cumulative impacts are expected as the works are away from the present Project.	No cumulative impacts are expected as the works are away from the present Project. On the other hand, the water quality in Deep Bay area will be enhanced.

7.7.4 Only the concurrent projects “Improvement of Yuen Long Town Nullah” and “Yuen Long Effluent Polishing Plant” will contribute to cumulative impacts on ecology during construction phase. As the most disturbance works of both projects will avoid the peak season of waterbirds, potential cumulative impacts to waterbirds as well as ecology are considered minor. While during operational phase, the combined effects of the projects will further enhance the water quality in the YLN as well as Deep Bay area. No adverse cumulative impacts on ecology are expected during operational phase.

7.8 Mitigation

General

7.8.1 According to the EIAO-TM Annex 16 and EIAO Guidance Note 3/2010, ecological impacts on important habitats and the associated wildlife caused by the proposed Project should be mitigated, in order of priority, avoidance, minimization, and compensation approaches to the maximum practical extent.

Consideration of avoidance

7.8.2 While the Project Site of the proposed barrage is situated within the WBA, the site and construction works are designed to be mainly confined to the YLN (i.e. man-made channelized watercourse with concrete bed) that direct impacts on all other recognized sites of conservation importance including Ramsar Site, Priority Site, WCA, SSSI and Conservation Area would be avoided.

Consideration of minimization

7.8.3 Consideration of alternative construction methods – Demolition using concrete crusher is quieter than demolition using breakers mounted on excavators that its construction noise level is comparable to other general construction activities. Concrete crusher also generates less vibration and dust than breakers during demolition works. However, concrete crusher is less efficient than breaker (approximate 50% slower) and its demolition rate would be more unreliable. In view of the tight programme, concrete crusher would be used for demolition works to be undertaken during dry season months and demolition using breakers mounted on excavators should only be undertaken during wet season when the wetland habitats nearby the Project Site are less sensitive outside the peak overwintering. Other quieter demolition methods including non-explosive demolition agent and the use of thermal lance and/or high-pressure water jets have also been considered but their demolition rate is also unreliable as well and thus not viable for the Project.

7.8.4 Due to the ground conditions and programme constraints, percussive piling works might be a more feasible foundation method. It is noted that alternative piling method will be considered as far as practicable during the detail design. In considering the construction noise, ecological impact and other engineering constraints, other quieter foundation methods, including bored piling by reverse circulation drill, raft foundation and shallow foundation, would be considered as far as possible.

7.8.5 Avoidance of percussive piling during winter - According to the ecological survey data from the present study, Shan Pui River recorded a relatively higher abundance of waterbirds in dry season, the potential impacts from noise disturbance to overwintering waterbirds are considered moderate (if percussive piling is adopted). In order to minimize the construction noise disturbance on the nearby wetland habitats and the associated disturbance-sensitive overwintering/migratory waterbirds, which are most abundant during the dry season months, the comparatively disturbing construction works i.e. percussive piling works and demolition using breakers mounted on excavators, would therefore be scheduled outside the dry season (i.e. November to March, which is the peak overwintering period of waterbirds).

7.8.6 Careful phasing of construction activities – The programme and phasing of the construction activities have been carefully planned to localise the construction disturbance within and to reduce the duration of high level of disturbances on sensitive wetland habitats and associated waterbirds. The proposed works will be conducted in 3 primary phases stated in Chapter 2. For example, excavation works within watercourse will be conducted in dry season to minimize the impacts to water quality and release of contaminants to aquatic habitats. Besides, all works for the barrage (the two pumping stations and tidal barriers) will not be constructed simultaneously, but will be constructed by 2 sections (one pumping station and half of tidal barriers at a time), to maintain the ecological connectivity, and to allow brackish water from Deep Bay entering YLN Section 4 that can provide wetland habitat for utilization of waterbirds.

7.8.7 Use of quality powered mechanical equipment – The Quality Powered Mechanical Equipment (QPME) system was developed by EPD to benchmark construction equipment items that are new, notably quieter, more environmentally friendly and efficient by QPME Labels. The contractor should source QPMEs for construction as far as practicable to further minimise the overall construction noise and other disturbance to the nearby wetland habitats and associated waterbirds to the maximum practical extent.

7.8.8 Other noise mitigation measures – Chapter 4 discusses only the noise mitigation measures required to fulfil relevant noise control standards stipulated under Annex 5 of EIAO-TM and recommends good construction site practice, use of quiet Powered Mechanical Equipment (PME), adoption of movable noise barriers and scheduling of PME/construction activities. In view of the presence of sensitive wetland habitats and the abundance of waterbirds (particularly migratory/overwintering ones) within the assessment area, other practicable effective mitigation measures on planning and construction of the Project have been fully explored and exhausted under this Project as described below to further abate the ecological impacts arising from construction noise disturbance on nearby wetland habitats and associated waterbirds, including careful phasing of construction activities, consideration of alternative construction methods, use of noise barriers and use of Quality Powered Mechanical Equipment (QPME).

7.8.9 Operation of tidal barrier to allow brackish waters flushing in – In order to mitigate the impacts of fragmentation in particular the water connectivity between the YLN Section 4 and Shan Pui River, as well as the loss of brackish water habitat at YLN Section 4, measures are being explored to retain the habitat between the existing inflatable dam and the proposed barrage as far as practicable. The operation of tidal barrier will be closed during high tide above 0.5mPD and will be opened below 0.5mPD (Appendix 2.5). The situation now is the waters from Deep Bay start flushing in above ~0.2mPD during high tide. Hence, the waters with sediment from Deep Bay can still be flushed into YLN Section 4 from ~0.2-0.5mPD during high tide before closure of tidal barriers The operation would facilitate an exchange of water, similar to the existing conditions, according to tidal fluctuations and enhance ecological connectivity through periodic opening of the tidal barriers. Additionally, the details of the proposed 300mm x 300mm ecological trench underneath the soffit of the tidal barriers is being investigated to serve a similar purpose when the barriers are closed. The necessary operation modes would be further explored in the Detailed Design Stage.

7.8.10 Discharge design to minimize the scouring effect to tidal mudflat – The performance of the discharge system would be assessed against the YLBS’ maximum discharge (i.e. under 200-year rainstorm event) and the configuration of the pumping stations is being optimised. Apart from under design weather events, no significant increase in discharge is anticipated as a result of the barrage. The orientation of the outlet and angle of discharge will be designed to prevent localized turbulent flows which could lead to scouring of the river bed and bank, thereby minimising significant changes to the existing sedimentation pattern / mudflats in Shan Pui River and Old Kam Tin River. Energy dissipators could be designed at the outlet to protect the downstream Shan Pui River from erosion by further reducing the flow velocity.

7.8.11 Reducing glare/lighting – No night-time construction works would be required under this Project (construction hours: 07:00 – 19:00) while the operations of the pumping stations and E&M room will be unmanned, only safety light will be turned on. Noting the Bent-winged Firefly is most active right after dusk, to avoid the potential disturbance impact on the firefly, any outdoor lighting associated with the construction works of the barrage after 18:00 should be avoided during May to September. In light of the presence of light sensitive mammal species of conservation importance, Great Cormorants that roost on trees at Nam Sang Wai and Bent-winged Firefly, the overall reduction of glare during both construction and operation phases should also be considered. A balance between lighting for safety, and avoiding excessive lighting can be achieved through the use of directional lighting to avoid light spill into sensitive areas, and control/timing of lighting periods of some facilities. Major construction site lighting should point inward and downward to minimize glare disturbance to wildlife at night. The intensity of light should also be controlled to the lowest possible level.

Consideration of mitigation

7.8.12 Translocation of Gobiopterus macrolepis – Within YLN Section 4 of the Project Site, fish species of conservation importance i.e. Gobiopterus macrolepis was recorded. Direct impact to this species is likely in the works area of the tidal barrier during construction phase, and mitigation measures are recommended. Capture-and-translocation of this fish species will be implemented in the works area of the tidal barrier and pumping station prior to construction works to minimize the impacts on this species of conservation importance.

7.8.13 Capture-and-translocation exercises for fish species of conservation importance were recommended in other EIA studies, and conducted in Hong Kong. For example, in the EIA study Drainage Improvements in Southern Lantau (AEIAR-093/2005), the proposed works at Pak Ngan Heung had the potential impacts to two fish species of conservation importance i.e. Flagtail Kuhlia marginata and Predaceous Chub Parazacco spilurus, and hence capture-and-translocation for the two species was proposed. Furthermore, in the course of preparing the Environmental Study Report of PWP Item No. 112CD (i.e. a drainage improvement works), a species of rare fish species Acrossocheilus parallens was found at the Kau Lung Hang Stream. The population of the species within the works area was captured and temporary kept in a set of fish tanks made of concrete beside the stream. The fish in the temporary fish tanks were then translocated back to the stream after the drainage improvement works. Although no precedent case of translocation of Gobiopterus macrolepis, a relative of this species from the same genus G. chuno is an ornamental fish and available on ornamental fish market. Potential translocation of Gobiopterus macrolepis is considered feasible.

7.8.14 The capture-and-translocation exercise should be undertaken by ecologists with relevant experience. Besides the primary target of Gobiopterus macrolepis, other aquatic species of conservation importance should also be translocated if encountered during the capture exercise. Captured individuals will be released to suitable habitats with records of the species during the exercises. As the works area of the tidal barrier subjects to tidal influence, it is recommended the capture exercise should be conducted after the works area boundary is encircled by cofferdam and the water is drained. It is preferred that the final cofferdam will be installed during low tide, allowing most fish or other aquatic fauna to evacuate with the ebbing tide, and the works area will further drain down by pump to facilitate the capture. Cofferdam should be maintained and kept intact to prevent recolonization of aquatic fauna in the works area after the capture survey.

7.8.15 Gobiopterus macrolepis were recorded along the Shan Pui River, Kam Tin River, the confluence of Shan Pui River and Kam Tin River, and the reedbed in Nam Sang Wai, all these locations can be considered as potential receptor sites for fish translocation.

7.8.16 The detailed fish translocation plan and ecologists involved in the translocation should be submitted to relevant authorities including AFCD for approval prior to commencement of the fish translocation. The plan should include brief description on pre-translocation fish survey, translocation methodology, identification of fish receptor site, post-translocation monitoring methodology, and measures to prevent recolonization of aquatic fauna in the works area of the tidal barrier.

7.8.17 With the implementation of the fish translocation programme, the direct encroachment impact on Gobiopterus macrolepis within the works area of the tidal barrier can be reduced to minor.

7.8.18 Use of noise barriers/acoustic screens – In order to further minimise the overall impacts on the nearby wetland habitats and associated waterbirds, particularly to the wetland habitats adjacent to the Project Site, noise barriers with absorptive materials of about 2-3m high will be erected along the sensitive sides of the Project Site, throughout the construction phase. The purpose is to screen the construction noise and human disturbance from the waterbirds during construction phase.

7.8.19 Adequate noise barriers should also be provided for the demolition using breakers mounted on excavators and percussive piling works, to further minimise the construction noise disturbance from these construction activities. Movable noise barriers should be provided to breakers mounted on excavator used for demolition works and acoustic mat should be provided to the piling plants around the rig.  The contractor should provide enclosure for construction equipment, especially static plants (e.g. generator), as appropriate to minimise the noise disturbance as far as practicable.

7.8.20 As ardeid night roost was recorded beside the Project Site of Kam Tin River, noise barriers with absorptive materials of about 2-3m high should be erected along the side close to the night roost location, that would screen human disturbance and noise disturbance to the night roost. As night roost may change from time to time, a pre-construction survey is recommended for areas within 100m from the Project boundary to confirm the location and status of the night roost. No construction works should be undertaken within 100m of any night roost confirmed by the pre-construction survey after 17:00 from February to September and 16:30 from October to January to avoid disturbance.

Enhancement opportunities

7.8.21 Revitalization – Upon operation of the Project, opportunities would be provided to revitalize the existing YLN. One of the revitalization components under the barrage scheme aims to enhance the ecology and biodiversity of the nullah. The targets should be focused on providing habitats to waterbirds as well as the aquatic fauna in particular Gobiopterus macrolepis. The nullah bed will be replaced with natural substrates and vegetation will be provided, to provide more microhabitats for aquatic life as well as waterbirds. It is expected YLN Section 4 will be enhanced that attracts more waterbirds for feeding and roosting after revitalization. Together with the operation of the tidal barrier, a high tide roost for waterbirds can be provided. Besides, the ecological connection would be another component for the revitalization. For example, there should not be continuous curb at the fringe between the tidal barrier and the watercourse that affects the aquatic fauna to-and-fro between Shan Pui River and YLN. Provision of a corridor should be considered to provide an access for semi-aquatic organisms such as Eurasian Otter.

7.8.22 Green opportunities – Greening opportunities, including green roofs and vertical greening on building structures, would be explored in the Project to further promote the ecological value of the Project Site. Further details of the relevant greening opportunities are discussed in Chapter 10 – Landscape and Visual Impact Assessment.

7.8.23 With the abovementioned mitigation measures, no secondary/induced/additional/synergistic impacts are anticipated. A summary of the impacts in construction and operational phases, with sources, receivers, nature, significance and mitigation required, are provided in Table 7.6.

Table 7.6 Summary of Construction Phase and Operational Phase Impacts

Impact	Sources	Receivers	Nature of impacts						Significance of ecological impact	Mitigation required
			Habitat quality	Species affected	Size / abundance	Duration	Reversibility	Magnitude
Construction Phase – Direct Impacts
Habitat loss	Parapet walls	Developed area	Very low ecological value	Very low diversity and abundance of waterbirds and aquatic fauna	Negligible size of developed area (heightening part will be on top of the existing parapet wall, new parapet wall will replace the existing railing)	Permanent	Reversible	Very small	No as it is not considered as a habitat loss	No
	Proposed barrage (tidal barrier, pumping stations, E&M room, channel widening and deepening works)	Plantation and YLN Section 4	Low ecological value for plantation; low to middle for YLN Section 4	Plantation: low diversity and abundance of flora and fauna; YLN Section 4: low to moderate diversity and abundance of waterbirds including those bird species of conservation importance, and Gobiopterus macrolepis	Tidal barrier: 0.09ha of channelized watercourse; Pumping stations: 0.17ha of channelized watercourse and 0.10ha of plantation; E&M room: 0.09ha of plantation; Channel widening and deepening works: 0.76ha of channelized watercourse and 0.10ha of plantation	Mostly permanent, but channel deepening works will be temporary	Not reversible	Plantation: very small; YLN Section 4: small	Plantation: minor; YLN Section 4/waterbirds including bird species of conservation importance and Gobiopterus macrolepis: minor to moderate; impact to Black-faced Spoonbill is considered minor	No specific mitigation measure for plantation loss under ecology, only compensatory planting under LVIA; translocation of Gobiopterus macrolepis; careful phasing of construction activities to maintain the water source in YLN Section 4 for waterbirds
	Revitalization	YLN Sections 1-4	Very low ecological value for Section 1-3; low to middle for Section 4	YLN Sections 1-3: very low diversity and abundance of waterbirds and aquatic fauna; Section 4: ditto	13.64ha	Temporary	Not reversible	Small	Not anticipated	It is an enhancement measure
Fragmentation (water connectivity)	Construction of tidal barrier and pumping station at YLN Section 4	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River: middle ecological value	Aquatic fauna including Gobiopterus macrolepis and semi-aquatic fauna including otter	Relatively low number of Gobiopterus macrolepis	Permanent	Not reversible	Small	Minor	Pumping stations and tidal barriers shall not be constructed simultaneously, to maintain the water connectivity
Fragmentation (flight path of waterbirds)	Construction of tidal barrier and pumping station at YLN Section 4, construction of parapet walls at Kam Tin River	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River and Kam Tin River: middle ecological value	Waterbirds	Low numbers of waterbirds compared to Shan Pui River, Nam Sang Wai and Deep Bay area	Permanent	Not reversible	Small for the barrage, very small for the parapet walls	Minor for the barrage; not expected for the parapet walls	No
Construction Phase – Indirect Impact
Water quality	All proposed construction works	Channelized watercourse including YLN, Shan Pui River and Kam Tin River	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River and Kam Tin River: middle ecological value	Aquatic fauna and waterbirds	Vary	Transient	Reversible	Small	Moderate	Follow water quality mitigation measures
Construction noise disturbance	Construction noise in particular piling	Sensitive habitats near the works area	Very low ecological value for Section 1-3; low to middle for Section 4; plantation in NSW: middle ecological value	Mostly waterbirds	Vary	Transient	Reversible	Moderate during piling process	Moderate	Follow noise mitigation measures, consider alternative piling method, and avoid percussive piling during dry season (if piling is unavoidable); no construction works should be undertaken within 100m of any night roost after 17:00 from Feb to Sep and 16:30 from Oct to Jan
Vibration disturbance	Due to piling	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River: middle ecological value	Mostly waterbirds	Vary	Transient	Reversible	Low	Minor to moderate during dry season; minor during wet season	Consider alternative piling method, Avoid percussive piling during dry season (if percussive piling is unavoidable)
Dust and human activities	Construction activities	Sensitive habitats near the works area	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River, tidal marsh, mangrove, plantation in NSW: middle ecological value; Reedbed: middle to high ecological value	Wildlife in the vicinity	Vary	Transient	Reversible	Low	Minor	Good site practice
Artificial lighting/glare	Works area	Sensitive habitats near the works area	Shan Pui River, tidal marsh, mangrove, plantation in NSW, the abandoned ponds within NSW, mitigation wetland: middle ecological value; Reedbed: middle to high	Nocturnal fauna including Bent-winged Firefly, ardeids night roost, the Great Cormorant roosting in NSW and the mammal species of conservation importance	Vary	Temporary	Reversible	Low	Minor to moderate	Night works will be avoided; Outdoor lighting associated with the construction works of the barrage after 18:00 should be avoided during May to September; Good site practice, reduction of glare/lighting
Construction disturbance to recognized sites, important habitats and species of conservation importance	Construction activities in particular noise	Wetland habitats in Shan Pui River and Nam Sang Wai	Shan Pui River, tidal marsh, mangrove, the abandoned ponds within NSW and semi-natural watercourse: middle ecological value; Reedbed: middle to high ecological value	Mostly waterbirds	Vary	Temporary	Reversible	Moderate during piling process	Moderate during dry season, minor to moderate during wet season	Follow noise mitigation measures, and avoid percussive piling during dry season; no construction works should be undertaken within 100m of any night roost after 17:00 from Feb to Sep and 16:30 from Oct to Jan
Operational Phase – Direct Impact
Habitat loss	Due to the presence of pumping station and E&M room	Plantation, WBA (YLN S4)	Plantation: low ecological value; YLN S4: low to middle ecological value	Low diversity and abundance of flora and fauna	0.29ha	Permanent	Not reversible	Low	Plantation: Minor; WBA: insignificant	No specific mitigation measure for plantation loss under ecology, only compensatory planting under LVIA; No net loss of wetland will be achieved by operation of tidal barrier to allow waters from Deep Bay flush in 50m beyond existing inflatable dam
Fragmentation (water connectivity)	Due to the presence of the proposed barrage	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River: middle ecological value	Aquatic fauna includes Gobiopterus macrolepis and semi-aquatic fauna includes otter	Relatively low number of Gobiopterus macrolepis	Permanent	Not reversible	Low	Minor	Operation of tidal barrier to allow waters from Deep Bay flush in and provision of ecological trench to maintain water connectivity
Fragmentation (flight path of waterbirds)	Due to the presence of the proposed barrage	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River and Kam Tin River: middle ecological value	Waterbirds	Low numbers of waterbirds compared to Shan Pui River, Nam Sang Wai and Deep Bay area	Permanent	Not reversible	Low	Minor	No
Operational Phase – Indirect Impact
Water quality (change of salinity)	With the tidal barrier blocking the exchange of waters	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River: middle ecological value	Food source of waterbirds and aquatic fauna	Vary	Permanent	Not reversible	Low	Insignificant	No
Change of hydrodynamics and sedimentation	Water discharge during operation of barrage	Channelized watercourse	Very low ecological value for Section 1-3; low to middle for Section 4; Shan Pui River: middle ecological value	Waterbirds and aquatic fauna	Vary	Permanent	Not reversible	Low	Insignificant	Discharge design to minimize scouring effect
Bird collision	Parapet walls, buildings	N/A	N/A	Birds	Vary	Permanent	Not reversible	Low	Minor	Environmental friendly design
Artificial lighting/glare	Pumping stations and E&M room	Sensitive habitats in the vicinity	Shan Pui River, tidal marsh, mangrove, plantation in NSW, the abandoned ponds within NSW, mitigation wetland: middle ecological value; Reedbed: middle to high	Nocturnal fauna including Bent-winged Firefly, nocturnal mammal, Great Cormorant and ardeids night roost	Vary	Temporary	Reversible	Low	Minor	Environmental friendly design
General disturbance to recognized sites, important habitats and species of conservation importance	Noise and human disturbance	Wetland habitats in Shan Pui River (WBA) and Nam Sang Wai (WCA)	Shan Pui River, semi-natural watercourse, tidal marsh, mangrove and abandoned ponds within NSW: middle ecological value; Reedbed: middle to high ecological value	Mostly waterbirds	Vary	Temporary	Reversible	Very low	Insignificant	No

7.9 Precautionary Measures

7.9.1 Where possible, suitable type of the future low flow pump for the barrage should be selected, which should be fish friendly to avoid injury or mortality of aquatic fauna caused by the operation of the low flow pump.

7.10 Residual Impacts

7.10.1 Only 0.29ha of plantation of low ecological value will be lost permanently, while no net loss of wetland will occur due to the decommissioning of the existing inflatable dam to release some space and the operation of tidal barrier can allow waters from Deep Bay flush in 50m beyond the existing inflatable dam to offset the wetland loss (0.26ha watercourse) due to the permanent structures at the channelized watercourse.

7.10.2 The unmitigated construction noise disturbances on migratory/overwintering waterbirds and their associated wetland habitats (particularly the key wetland habitats for the waterbirds and the wetland habitats adjacent to the Project Site) during dry season as well as on resident waterbirds that are present all year round and the key wetland habitats for those species during wet season would be a key issue of the Project. Further to the provision of noise barriers for the hydraulic breakers mounted on excavators used in demolition works proposed, all other practicable effective mitigation measures have been fully explored and exhausted in order to further reduce the noise impact arising from the construction to the wetland habitats and associated waterbirds, particular migratory/overwintering ones. Noise mitigation measures proposed to reduce the overall all construction disturbance from the Project Site include erection of noise barriers with absorptive materials of about 2-3m high along the works area, provision of noise barrier/acoustic mat to piling plant and breakers, provision of noise enclosure for construction equipment and use of QPME. Furthermore, in light of the presence of migratory/overwintering waterbirds within the assessment area, all percussive piling works and demolition works using breaker mounted on excavator will only be conducted during wet season when the area is utilized mainly by more-disturbance-tolerant resident waterbirds.

Residual impacts to wetland habitats immediately adjacent to the Project Site and associated migratory/overwintering waterbirds during dry season

7.10.3 While some affected habitats are located immediately adjacent to the Project Site (YLN Section 4, Shan Pui River, Nam Sang Wai), they supported generally lower number of avifauna species of conservation importance when compared to the Deep Bay area. With the avoidance of demolition using breakers mounted on excavators and percussive piling, as well as the implementation of the abovementioned noise mitigation measures proposed to reduce the overall all construction disturbance from the Project Site, it is considered that there would be no significant noise disturbance on the wetland habitats adjacent to the Project Site. Furthermore, the key wetland habitats are well-connected to the wetland habitats adjacent to the Project Site and there are ample of continuing and extensive wetland habitats in the vicinity of the assessment area (including about 1,500 ha of wetland in the Ramsar Site north to the assessment area), given the ability of birds to move away from sources of disturbance, no unacceptable residual adverse ecological impacts on the migratory/overwintering waterbirds at the wetland habitats adjacent to the Project Site are anticipated.

Residual impacts to wetland habitats further from the Project Site and associated migratory/overwintering waterbirds during dry season

7.10.4 Other affected wetland habitats within the assessment area and the key wetland habitats that supported the greatest numbers of overwintering/migratory waterbirds during dry seasons are located further from the Project Site and the magnitude of construction noise disturbance experience by waterbirds is expected to be further reduced. Additional noise mitigation measures have been proposed to avoid percussive piling and demolition using breakers mounted on excavators during dry season and to lower the overall construction noise levels of the construction activities, no unacceptable residual adverse ecological impacts on these wetland habitats and the associated migratory/overwintering waterbirds are anticipated.

7.10.5 Reference has been made to other EIA studies that were also nearby sensitive wetland habitats on the acceptability of the noise impacts from non-percussive construction activities on waterbirds. For instance, the works boundary of a ventilation building of Express Rail Link (XRL) (MTRC 2009) was located only around 15m from fishponds in WCA. While no percussive piling works were required, the construction tasks of the building required were quite similar to general construction activities required under this Project (e.g. superstructure). Ecological monitoring of avifauna community was conducted in wetland habitats nearby works area in fishponds within WCA in Mai Po and drainage channel upstream of Kam Tin River at Tai Kong Po during the construction from 2010 to 2017 (MTRC 2009; MTRC 2018). Throughout the monthly ecological monitoring, while fluctuations of avifauna population were encountered, no adverse impacts from the construction works on the population or composition of avifauna communities had been identified with the proper implementation of appropriate mitigation measures (MTRC 2018).

Residual impacts to wetland habitats and associated resident waterbirds during wet season

7.10.6 While percussive piling works and demolition using breakers mounted on excavators would be conducted during wet season, the magnitude of the percussive piling works and demolition using breakers mounted on excavators during wet season is expected to be effectively controlled with the implementation of additional mitigation measures proposed, including erection of noise barriers with absorptive materials of about 2-3m high, provision of noise barrier/acoustic mat to piling machines and breakers, provision of noise enclosure for construction equipment and use of QPME. It is also worth noting that the 500m assessment area is utilized mainly by low number of disturbance-tolerant resident waterbirds in wet season that would be a lot less affected than the migratory/overwintering waterbirds. No unacceptable residual adverse ecological impacts on wetland habitats within the assessment area and the associated resident waterbirds during wet season are anticipated.

7.11 Monitoring and Audit Requirements

7.11.1 Mitigation measures have been proposed under this Project to control any potential indirect impacts to the nearby sensitive wetland habitats and associated wildlife, particularly waterbirds. Implementation of the recommended mitigation measures described above (e.g. avoidance of recognized sites of conservation importance, avoidance of percussive piling and demolition using breakers mounted on excavators during dry season, provision of noise barriers along existing fence of Project Site, provision of movable noise barriers/acoustic mat on breakers and piling plants, use of enclosure for construction plant, use of QPME, restriction of construction hours of construction activities with PME, implementation of all good site practices etc.) should be monitored and audited weekly throughout the construction phase to ensure proper implementation of the proposed mitigation measures. In case of non-compliance, the contractor should be informed to strengthen the proposed mitigation measures accordingly.

7.11.2 Monthly ecological monitoring in both wet and dry seasons, focusing on avifauna species of conservation importance and overwintering waterbirds utilizing wetland habitats within 500m of the Project Site, should be conducted during construction phase to monitor the effectiveness of proposed mitigation measures and detect any unpredicted indirect ecological impacts arising from the proposed Project. Remedial actions can then be recommended, where appropriate, based on the impact monitoring results.

7.11.3 Monthly monitoring of the area within 100m from the Project boundary to check the location and status of any active night roost should be conducted during the construction phase to monitor the effectiveness of proposed mitigation measures and detect any unpredicted indirect ecological impacts arising from the proposed Project. Remedial actions can then be recommended, where appropriate, based on the impact monitoring results.

7.11.4 Details of environmental monitoring and audit (EM&A) requirements are discussed in the separate EM&A Manual.

7.12 Conclusion

7.12.1 A literature review and ecological field surveys have been conducted. A total of 14 habitat types, including channelized watercourse, semi-natural watercourse, pond, abandoned wet agricultural land/freshwater marsh, tidal marsh, mangrove, reedbed, mitigation wetland, shrubland, agricultural land, mixed woodland, plantation and wasteland and developed area, were recorded within the 500m assessment area, with channelized watercourse, plantation and developed area being the habitats recorded within the Project Site. The ecological values of the wetland associated habitats including channelized watercourse (only YLN Section 4, SPR, KTR), semi-natural watercourse, pond, abandoned wet agricultural land/freshwater marsh, tidal marsh, mangrove, reedbed and mitigation wetland are at least low to middle, middle or middle to high. The other habitats, except shrubland, plantation in NSW, which are of low to middle ecological value, are considered of low or very low ecological value. Species of conservation importance recorded within the 500m assessment area included 2 flora, 3 mammals, 51 avifauna, 5 herpetofauna, 9 butterflies, 3 odonates, 1 aquatic fauna and the endemic Bent-winged Firefly. Only 14 avifauna of very low abundance and 1 fish species of conservation importance were recorded within the Project Site.

7.12.2 Potential direct impacts on natural habitats and recognized sites of conservation importance within the assessment area except WBA inside Project Site have been avoided through confinement of construction works within the proposed works area. Only 0.29ha of plantation of low ecological value will be lost permanently, while net wetland loss will not occur due to the decommissioning of the existing inflatable dam to release some space and the deepening of the bed of the watercourse together with the operation of tidal barrier can allow waters from Deep Bay flush in 50m beyond the location of the existing inflatable dam to offset the wetland loss (i.e. 0.26ha watercourse) due to the permanent structures at the channelized watercourse.

7.12.3 Major indirect impacts due to construction noise disturbances from demolition using breakers mounted on excavators and piling works on key wetland habitats within the assessment area and in close proximity to the Project Site as well as migratory/overwintering waterbirds have been avoided through scheduling of percussive piling works and demolition using breakers mounted on excavators outside dry season (i.e. November to March, which is the peak overwintering period of waterbirds).

7.12.4 As the YLN Section 4 will be enhanced ecologically, with the design of the tidal barrier to allow brackish waters flushing in the YLN, no negative ecological impacts due to habitat loss are predicted. On the other hand, the flight-line of waterbirds to-and-fro the YLN Section 4 and Shan Pui River were limited, with the manoeuvrability of waterbirds and the unlikely feeding and roosting grounds in the upstream of YLN, potential impacts to flight-line of waterbirds due to the barrage is considered minor.

7.12.5 Hydrodynamics at the Old Kam Tin River as well as Shan Pui River will not be changed significantly due to the large waterbody of Deep Bay. While the scouring effects to the exposed mudflat during low tide can be minimized by good discharging design. As there will be no strong artificial lighting, with the proposed mitigation measure in place, potential impacts from light to nocturnal life including Bent-winged Firefly are considered minor.

7.12.6 Mitigation measures have been proposed during construction stage. According to the ecological survey data from present study, Shan Pui River recorded a relatively higher abundance of waterbirds in dry season. In order to minimize the construction noise disturbance on the nearby wetland habitats and the associated disturbance-sensitive overwintering/migratory waterbirds, which are most abundant during the dry season months, the comparatively disturbing construction works i.e. percussive piling works and demolition using breakers mounted on excavators, would therefore be scheduled outside the dry season (i.e. November to March, which is the peak overwintering period of waterbirds). In addition, a pre-construction survey is recommended for areas within 100m from the Project boundary to confirm the location and status of the night roost. Ardeid night roost was recorded at a site along Kam Tin River. No construction works should be undertaken within 100m from any night roost confirmed by the pre-construction survey after 17:00 from February to September and 16:30 from October to January to avoid disturbance to ardeid night roost. Within YLN Section 4 of the Project Site, fish species of conservation importance i.e. Gobiopterus macrolepis was recorded. Direct impact to this species is likely in the works area of the tidal arrier during construction phase, and translocation of this species is recommended. Capture-and-translocation of this fish species will be implemented in the works area of the tidal barrier and pumping station prior to construction works to minimize the impacts on this species of conservation importance.

7.12.7 With the implementation of the recommended mitigation measures (e.g. avoidance of percussive piling and demolition using breakers mounted on excavators and use of alternative quieter construction method during peak overwintering period within dry season; provision of noise barriers around Project Sit, provision of movable noise barrier/acoustic mat for piling plants and breaker; use of enclosure for construction plant, use of QPME; restriction of construction activities within specified months, etc.), no unacceptable adverse residual impacts would be expected during construction or operational phase.

7.12.8 Ecological monitoring should be conducted during construction phase to monitor the effectiveness of proposed mitigation measures and detect any unpredicted indirect ecological impacts arising from the proposed Project and the implementation of mitigation measures would be subject to regular audit as part of the EM&A programme.

7.13 References

(1) Corlett, R. T., Xing, F., Ng, S. C., Chau, L. K. C., & Wong, L. M. Y. (2000). Hong Kong vascular plants: distribution and status. Memoirs of the Hong Kong Natural History Society, 23: 1-157.

(2) Cutts, N., Hemingway, K. and Spencer, J. 2013. Waterbird Disturbance Mitigation Toolkit Informing Estuarine Planning & Construction Projects. Produced by Institute of Estuarine & Coastal Studies (IECS). University of Hull.

(3) Cutts, N., Phelps, A. and Burdon, D. 2008. Construction and Waterfowl: Defining Sensitivity, Response, impacts and Guidance. Institute of Estuarine and Coastal Studies (IECS). University of Hull.

(4) Farmer, A.M., 1993. The effects of dust on vegetation - a review. Environmental pollution, 79(1): 63-75.

(5) Fellowes, J.R., Lau, M.W.N., Dudgeon, D., Reels, G.T., Ades, G.W.J., Carey, G.J., Chan, B.P.L, Kendrick, R.C., Lee, K.S., Leven, M.R., Wilson, K.D.P. and Yu, Y.T. 2002. Wild animals to watch: terrestrial and freshwater fauna of conservation concern in Hong Kong. Memoirs of the Hong Kong Natural History Society 25: 123-159.

(6) Hong Kong Jockey Club (HKJC). 2005. Proposed Extension of Public Golf Course at Kau Sai Chau Island, Sai Kung. Environmental Impact Assessment Report. Prepared by Binnie Black & Veatch Hong Kong Ltd for the Hong Kong Jockey Club.

(7) Hong Kong Observatory (HKO), 2020. https://www.hko.gov.hk/en/index.html

(8) Klein, M.L., Humphrey, S.R. and Percival, H.F. 1995. Effects of ecotourism on distribution of waterbirds in a wildlife refuge. Conservation Biology 9: 1454-1465

(9) Lee, W.H., Liu, E., Choi, I.C., Tsim, S.T. (2004). Summer Breeding and Winter Night Roosting Sites of Egrets in Hong Kong 2003. Hong Kong Biodiversity (Agriculture, Fisheries and Conservation Department newsletter) (6): 10-12

(10) MTR Corporation Ltd (MTRC). 2009. Express Rail Link. Environmental Impact Assessment Report. Prepared by AECOM Asia Co Ltd for MTR Corporation Ltd.

(11) MTR Corporation Ltd (MTRC). 2010. South Island Line (East). Environmental Impact Assessment Report. Prepared by AECOM Asia Co Ltd for MTR corporation Ltd.

(12) MTR Corporation Ltd (MTRC). 2018. Archive of Environmental Monitoring and Audit Reports for Express Rail Link. https://x.dantemanager.net/monitor/EnvPerformance!listEMA.action

(13) Qin et al., 2017. Threatened Species List of China’s Higher Plants. Biodiversity Science 2017, Vol. 25, Issue (7): 696-744.

(14) Yip, J. K., Yip, J. K. L., Liu, E. K. Y., Ngar, Y. N., & Lai, P. C. C. (2010). A floristic survey of marshes in Hong Kong. Hong Kong Biodiversity 19: 7-16.