8 Ecological impact

8.1 Introduction

8.1.1 The following section presents the results of an assessment of potential ecological impacts resulting from the Project. As stated in the EIAO TM, the aim of ecological impact assessment is to protect, maintain or rehabilitate the natural environment. A literature review and field surveys were undertaken to identify ecological sensitive receivers, and the ecological importance of habitats/species potentially affected by proposed works was evaluated. The scale of possible ecological impacts resulting from the proposed works was assessed, and necessary mitigation measures were identified. Cumulative impacts resulting from this and other Projects in the area were assessed. Residual ecological impacts were assessed, and ecological monitoring and audit requirements identified.

8.2 Environmental Legislation, Policies, Plans, Standards and Criteria

8.2.1 Guidelines, standards, documents and HKSAR Government ordinances and regulations listed in the following sections were referred to during the course of the ecological impact assessment.

8.2.2 The Country Parks Ordinance (Cap. 208) provides for the designation and management of country parks and special areas. Country parks are designated for the purpose of nature conservation, countryside recreation and outdoor education. Special Areas are created mainly for the purpose of nature conservation.

8.2.3 The Forests and Countryside Ordinance (Cap. 96) prohibits felling, cutting, burning or destroying of trees and growing plants in forests and plantations on Government land. Related subsidiary Regulations prohibit the selling or possession of listed restricted and protected plant species. The list of protected species in Hong Kong which comes under the Forestry Regulations was last amended on 11 June 1993 under the Forestry (Amendment) Regulation 1993 made under Section 3 of the Forests and Countryside Ordinance.

8.2.4 Under the Wild Animals Protection Ordinance (Cap. 170), designated wild animals are protected from being hunted, whilst their nests and eggs are protected from injury, destruction and removal. All birds and most mammals, including marine cetaceans, are protected under this Ordinance. The Second Schedule of the Ordinance which lists all the animals protected was last revised in June 1992.

8.2.5 According to the Town Planning Ordinance (Cap. 131), the Town Planning Board shall undertake the preparation and amendments to statutory plans. The statutory plans may show of make provision for, among others, country parks, coastal protection areas, sites of special scientific interest, green belts or other specified uses that promote conservation or protection of the environment.

8.2.6 Chapter 10 of the HKPSG covers planning considerations relevant to conservation. This chapter details the principles of conservation, the conservation of natural landscape and habitats, historic buildings, archaeological sites and other antiquities. It also describes enforcement issues. The appendices list the legislation and administrative controls for conservation, other conservation related measures in Hong Kong and government departments involved in conservation.

8.2.7 Annex 16 of the EIAO TM sets out the general approach and methodology for assessment of ecological impacts arising from a project or proposal, to allow a complete and objective identification, prediction and evaluation of the potential ecological impacts. Annex 8 recommends the criteria that can be used for evaluating habitat and ecological impact.

8.2.8 EIAO Guidance Note No. 6/2002 clarifies the requirements of ecological assessments under the EIAO.

8.2.9 EIAO Guidance Note No. 7/2002 provides general guidelines for conducting ecological baseline surveys in order to fulfil requirements stipulated in the EIAO TM.

8.3 Assessment Methodology & Criteria

Assessment Methodology

8.3.1 Existing literature documenting the ecology of Hong Kong and the Sai Kung area in particular was reviewed. Relevant sources included:

Binnie Black & Veatch HK Ltd. (2001) Preliminary Environmental Review for Drainage Improvements in Sai Kung.

Chan, B.P.L. (2001) Sustainability and Biodiversity: the Impact, Alternative Design and Prospects for Restoration of Channelized Lowland Streams in Hong Kong: Unpublished Ph.D. thesis, University of Hong Kong

Gallacher, D. (2000) The use of Benthic Macroinvertebrate Communities as Biomonitors of Hong Kong Streams. Unpublished Ph.D. Thesis. The University of Hong Kong, Hong Kong: 197pp.

Carey, G.J., Chalmers, M.L., Diskin, D.A., Kennerley, P.R., Leader, P.J., Leven, M.R., Lewthwaite, R.W., Melville, D.S., Turnbull, M., and Young, L. (2001): The Avifauna of Hong Kong. Hong Kong Bird Watching Society, Hong Kong.

Lau, M.W.N. & Dudgeon, D. (1999) Composition and distribution of Hong Kong amphibian fauna. Memoirs of Hong Kong Natural History Society 22:1-79.

Wilson, K.D.P. (1997) An annotated checklist of the Hong Kong dragonflies with recommendations for their conservation. Memoirs of the Hong Kong Natural History Society 21: 1-68.

Tam, N.F.Y & Wong, Y.S. (1997). Ecological Study on Mangrove Stands in Hong Kong. Submitted to AFD.

8.3.2 To confirm the validity of and update existing data, ecological surveys covering both the wet and dry seasons were conducted from October 2002 to June 2003. The surveys covered all areas within 500m of the proposed works areas. The surveys comprised:

Habitat/vegetation surveys

8.3.3 Habitats inside the Assessment Areas were identified and mapped. Surveys were undertaken in the wet season (October 2002) and dry season (January/February 2003). Plant species, relative abundance and growth forms were recorded. Identification of species and status in Hong Kong were made with reference to AFD (1993), AFCD (2002) and Corlett et al. (2000).

Avifauna Surveys

8.3.4 Avifaunal surveys of each Assessment Area were conducted on a monthly basis over 9 months, covering the wet and dry seasons (from October 2002 – June 2003). Additional night surveys were conducted in December 2002 (Sai Kung) and May 2003 (Pak Kong and Ho Chung) to record any nocturnal avifauna. Species present and relative abundance of species was recorded.

Herpetofauna & Mammal Surveys

8.3.5 Herpetofauna/mammal surveys of each Assessment Area were conducted. Species present and relative species abundance were recorded by direct observation, searching potential microhabitats, listening for calling animals, and searching for signs of animal activity (e.g., burrows, scats etc.). The herpetofauna/mammal surveys covered the wet (May & June 2003) and dry seasons (November 2002), and were conducted during the day and night.

Terrestrial Insect Surveys

8.3.6 Surveys of adult butterflies and odonates were conducted in each Assessment Area, covering the wet (April & May 2003) and dry seasons (November 2002). Species present and relative species abundance were recorded by direct observation.

Freshwater Community Surveys

8.3.7 Surveys of fish populations in Ho Chung River, Pak Kong River, and Sai Kung River were conducted in the wet (May 2003) and dry seasons (November 2002, February 2003). Fish were surveyed using aquatic hand nets at various microhabitats. Gill nets were also used to sample fishes at lower river habitat and estuarine areas at Ho Chung and Pak Kong Rivers.

8.3.8 Surveys of freshwater macroinvertebrate populations in Ho Chung River, Pak Kong River, and Sai Kung River were conducted in the wet (May 2003) and dry (November 2003) seasons. Macroinvertebrates were sampled using a 500mm mesh D-framed net.

Marine Habitat Surveys

8.3.1 Surveys of intertidal habitats including mangrove, mudflat/sandflat habitats in the Assessment Areas were undertaken. Vegetation surveys were conducted on mangrove stands.

8.3.2 Intertidal communities in the Assessment Areas were surveyed in the dry and wet season (March and May 2003). Species present and the abundance of species were recorded by intensive direct observation at low tide.

8.3.3 Subtidal communities were surveyed at Ho Chung and Pak Kong estuaries and at Sai Kung in the wet season (May 2003). At Ho Chung and Pak Kong, bottom mud samples were taken using a corer at 3 intervals approximately 100m apart and from the deepest part (middle) of the estuarine channel. Samples were sieved and stained/preserved for identification. Species present and relative abundance of species in soft bottom habitats were recorded. At Sai Kung, species in the subtidal were recorded by intensive direct observation.

Impact Assessment

8.3.1 Potential ecological impacts arising from the Project were assessed following EIAO TM Annex 16 guidelines and the impacts evaluated based on criteria in EIAO TM Annex 8.

8.4 Description of the Environment

Areas of Conservation Interest

8.4.1 The location of recognised areas of conservation interest within the three 500m Assessment Areas are outlined in Figures 8.1a-c.

Coastal Protection Areas (CPA)

8.4.2 CPA zones are found close to all three proposed drainage improvement works areas. The most extensive CPA lies at the mouth of the Ho Chung River, and encompasses intertidal habitats including mangrove and estuarine mudflats.

8.4.3 According to the Hebe Haven and Pak Kong & Sha Kok Mei Outline Zoning Plans (No. S/SK – HH/3 and S/SK-PK/6 respectively), the intention of CPA zones is to retain natural coastlines free from or with minimum development so as to retain the natural character [of the coastline] with interesting features. The areas may also serve as natural buffers which would shelter nearby developments against the effects of coastal erosion.

Conservation Areas

8.4.4 Upland areas supporting a variety of habitat types including shrubland, secondary and Fung Shui woodland are zoned Conservation Areas (CA’s) in the three Assessment Areas. Most CA’s are relatively distant from the proposed works areas, being located on hillsides above the river valleys where proposed works would be undertaken.

8.4.5 Conservation Areas serve to retain the existing natural character and safeguard intrinsic landscape qualities of the zoned areas. They may also be used to separate sensitive natural systems such as Sites of Special Scientific Interest from the adverse effects of development (OZP Nos. S/SK – HH/3 and S/SK-PK/6 refer).

Special Area and Country Park

8.4.6 The Tsiu Hang Special Area was designated in 1987, covering an area of 24ha adjacent to Ma On Shan Country Park on the Pak Sha Wan Peninsula. The area lies approximately 270m Northeast of proposed Pak Kong River works area (Figure 8.1b refers). Tsiu Hang Special Area and Ma On Shan Country Park are both zoned as Country Park under the Hebe Haven OZP (No. S/SK – HH/3).

8.4.7 An outdoor study centre (The Lions Nature Education Centre) was opened at the Tsiu Hang Special Area in 1991. The Centre consists of a rich collection of fruit-bearing and amenity trees, vegetables and other local vegetation, in addition to indoor exhibitions.

Habitat Type and Vegetation

8.4.8 The three Assessment Areas were found to be broadly similar in terms of habitat composition as a result of geographic proximity and similar land use patterns. The lower river basins comprised a mix of disturbed habitat types, including cultivation land and village areas. Most of the cultivation land has gradually become abandoned or inactive in the past 30 years, giving way to the development of village houses and other commercial or community facilities. Hiram’s Highway runs south-west/north-east through all three Assessment Areas near the river mouths. Most areas adjacent to the highway were occupied by residential and commercial developments.

8.4.9 Habitats identified during the field surveys included Rivers and Streams, Cultivation Land, Woodland and Fung Shui Woodland, Shrubland, Developed and Village Areas, Mangroves, and Marine Habitat. Habitat maps are given in Figure 8.2. Representative photographs of habitats are given in Appendix 8.1. Photographs of species of conservation interest are given in Appendix 8.2. Plant species recorded in each works and Assessment Area are listed in Appendix 8.3. A more detailed description of habitats recorded in the Assessment Areas is given in the following sections.

Rivers, Streams &Riparian Vegetation

8.4.10 Ho Chung, Pak Kong and Sai Kung Rivers are typical Hong Kong rural lowland rivers in terms of morphology, hydrology and degree of human disturbance. The rivers generally had slow to moderate water flow resulting from low gradient. The lower reaches of Ho Chung and Pak Kong Rivers were tidally influenced. The banks of all three rivers have experienced a long history of human modification, with some of the sections cemented, while the river bottom remains largely natural comprising rock and pebble substratum.

8.4.11 The riparian vegetation at some sections was well established with most species planted or introduced. Common riparian mature trees include Cleistocalyx operculata, Ficus spp. Celtis sinensis, Mararanga tanarius, and some fruit trees. Riparian vegetation comprised various grasses, herbs, ferns, shrubs, climbers and trees.

8.4.12 No protected plant species were recorded from the three rivers or adjacent riparian zones. Two small trees along with several seedlings of one tree species of conservation interest, Ehretia acuminata, were recorded at one location on the bank at Ho Chung River. This species is listed as “very rare”, being recorded from only one site in Hong Kong by Corlett et al., (2000). However, additional records of the species at Deep Water Bay, Tai Wai, Sha Tin and Kam Tin are reported in the Checklist of Hong Kong Plants (AFCD, 2003).

8.4.13 In addition to Sai Kung River, the smaller Sha Ha stream would be affected by drainage works at the Sai Kung site. West of Tai Mong Tsai Road, the stream is semi-natural, supporting extensive riparian vegetation. East of road, the stream has been significantly degraded by on-going infrastructure works. The natural course of stream has been altered, and was found to flow over exposed soil and is subject to extremely high levels of suspended sediment. No aquatic fauna or flora were recorded from this section.

Cultivation Lands

8.4.14 Cultivation lands are one of the major land features of the lower river valleys in the three Assessment Areas. Active agricultural land was found to produce a variety of ornamental plants such as citrus and peach species. Some vegetables were also grown at some small patches of cultivation land but not on a large scale. Fruit trees were commonly planted within the cultivation lands and around villages in all three Assessment Areas. Some areas of cultivation lands were inactive or abandoned, and found to support various exotic or native grasses, herbs, and some trees, (e.g., Microstegium ciliatum, Mikania micrantha, Paspalum spp., Alocasia macrorrhiza and Macaranga tanarius).

8.4.15 One locally rare herb species, a Mongolian Dandelion (Taraxacum mongolicum) was recorded from cultivation land in the Sai Kung Assessment Area. Although rare in Hong Kong (recorded from two localities: AFCD, 2003), this species is common and widely distributed through China.

Woodland and Fung Shui Woodland

8.4.16 A small Fung Shui woodland (app. 1ha) was recorded north of the Tin Hau Temple close to the proposed Ho Chung River works area. Dominant mature trees at the habitat included Cinnamomum camphora. A few large camphor trees were treated as “Fungshui” trees by local villagers. Fung Shui Woodland was also recorded to the north of Ho Chung Village. The woodland supported numerous large mature native trees, in particular Endospermum chinense. Additionally, several Tutcheria championii trees were recorded from this habitat type. Tutcheria championii is a protected species under the Forestry Regulation of HKSAR.

8.4.17 Natural woodland habitats were distributed across the upper catchments of all three Assessment Areas. The majority of woodlands were secondary in origin, supporting small to medium size trees, and were likely to have established over the past 50 years or so. Dominant tree species in this habitat include Machilus spp., Ficus spp., Camphor trees and Euphorbiaceae species. A well established plantation woodland was recorded at Sha Ha, close to the fringe of cultivation land to the west of Sai Kung River. The trees in the woodland were dominated by a single exotic species, Lophostemom confertus, with an average height of 12m. Plant species diversity recorded in both natural and planted woodlands was found to be moderately high, comprising a mix of native and introduced species. The protected shrub species Pavetta hongkongensis was recorded at several locations along woodland fringes in the Sai Kung Assessment Area.

Shrubland

8.4.18 Small patches of shrubland varying from approximately 1m-3m in height were recorded from all three Assessment Areas. Species composition in these habitats was similar to nearby woodlands, with common species including Ficus spp., Schefflera octophylla, Macaranga tanarius and Rhus spp. No rare or protected species were recorded from this habitat type.

Village and Developed Areas

8.4.19 A substantial part of all three Assessment Areas was covered by roads, tracks, commercial facilities and village dwellings. Furthermore, the seafronts of the Ho Chung and Sai Kung Assessment Areas were found to be extensively developed, with industrial properties, marina, piers, residential developments and village houses found along the coastline.

Mangrove

8.4.20 Stands of mangrove occurred on the fringes of both the Ho Chung and Pak Kong River estuaries. Elsewhere in the Assessment Areas, mangrove areas were also found adjacent to Ta Ho Tun villages at the northern shores of Hebe Haven.

8.4.21 Mangroves at Ho Chung and Pak Kong were dominated by Kandelia candel, with other ‘true mangrove’ species including Excoecaria agallocha, Aegiceras corniculatus, Avicennia marina, Acanthus illicifolius and the restricted Bruguiera gymnorrhiza. Along the landward margins of the mangrove, ‘mangrove associates’ were small trees of Hibiscus tiliaceus, Cerbera manghas, shrubs Pandanus tectorius, Clerodendrum inerme and climbers Derris trifoliata. Other occasional coastal plants were also present including Scaevola sericea and Suaeda australis.

8.4.22 The Ho Chung mangrove formed the most extensive cover in the Assessment Areas with some trees > 4m in height. The Pak Kong mangrove had a smaller area with mangrove trees generally not exceeding 2m. The mangroves within the Assessment Areas appeared to be in a healthy condition.

Marine Habitat

8.4.23 Ho Chung and Pak Kong Rivers flow into estuary areas formed by tidally exposed mudflats. During spring tide, tides fall to low levels exposing most of the estuary areas as mudflat. At Ho Chung, mudflat comprises virtually the entire marine area within the Assessment Area divided by a shallow estuary channel. Similarly, at Pak Kong, the mudflat when exposed is extensive within the estuary and extends up to 100m from the high water mark. The mudflats support an abundance of invertebrates which in turn attract some shorebirds. The habitat serves as a feeding ground for small populations of herons, wagtails, plovers and egrets. In the wet season at Pak Kong and Ho Chung, shore combers were often seen raking and digging the mud to collect clams in nets and sacks.

8.4.24 At Sai Kung, the intertidal area is formed by a gently sloping silty/muddy sandflat with small cobbles. Coarser sand occurs towards the high shore. The shore is predominantly used as a recreational beach.

8.4.25 Flora on the Ho Chung and Pak Kong mudflat was dominated by Entromorpha sp. with Ulva lactuca also occasionally found. These macroalgae attained high cover on the mudflats in the dry season but was virtually absent in the wet season.

8.4.26 One small but apparently healthy patch of the rare seagrass Halophila ovata (approximately 15m²) occurred on the intertidal mudflat approximately 250m from the Pak Kong River mouth. A few individual plants were found on the Ho Chung estuary mudflat but were in a very poor condition. Halophila ovata is considered rare in Hong Kong (Corlett et al. 2000) and with fragmented populations (Fong 1999).

Fauna

8.4.27 Fauna recorded in the Assessment Areas during recent surveys are listed in Appendix 8.4.

Aquatic Communities

Fish

8.4.28 A total of thirty freshwater, estuarine and marine fish species were recorded during the surveys. Fish species diversity was relatively high at Ho Chung River with 25 species recorded, medium at Pak Kong River (17 species) and low at Sai Kung River (8 species). Differences in the number of species was partially due to the larger river channels at Ho Chung and Pak Kong River, and the fact that intertidal and estuarine habitats at the Sai Kung River fell largely outside of the Assessment Area. The exotic fish species Poecilia reticulata and the native species Rhinogobius duospilus were the most common and abundant fishes in the freshwater habitats of the three rivers. Estuarine fish were represented by common species of Chelon spp. Mugil cephalus and tilapia (Sarotherodon massambicus). A parasitic fish Echeneis naucrates was seen attached to a Mugil cephalus at Ho Chung River. A juvenile Japanese eel (Anguilla japonica) was also recorded at Ho Chung River. In addition, a population Fung Shui fish (Cyprinus carpio var. viriduviolaceus) with a few other freshwater fish species were released and maintained at the Ho Chung River by local villagers.

8.4.29 One species of conservation interest, Orange Peacock Puffer (Takifugu ocellatus) was recorded from Pak Kong and Ho Chung Rivers. Populations in Hong Kong are considered of local conservation concern by Fellowes et al. (2002) because of the restricted records of breeding sites in Hong Kong. Its capture in Pak Kong and Ho Chung Rivers may suggest the estuaries are used for breeding by this species. This being the case, the estuarine reaches of these two Rivers may provide an important breeding habitat for the species.

8.4.30 Gill netting at the estuary of Ho Chung and Pak Kong rivers yielded five crab and two fish species. The recorded crabs were Portunus pelagicus, c.f. Thalamita danae, Portunus sp., Charybdis natator and Scylla serrata. The two fish species caught at Ho Chung were Saurida elongate and Leiognathus brevirostris, which are common in coastal waters.

Freshwater Macroinvertebrate Communities

8.4.31 Macroinvertebrate communities at the three rivers comprised of Mollusk, Crustacea and Insecta. Species diversity of benthic fauna was found to be relatively low, possibly reflecting moderate impacts to all three streams from agricultural run-off and pollution from other sources.

8.4.32 Freshwater shrimps, especially Caridina cantonensis were abundant and dominated at Sai Kung River. Dipteran larvae, mainly Orthorcladinae, were more numerous in Pak Kong and Ho Chung River than at Sai Kung River. Common stream benthos included the snail Brotia hainanensis, Long Armed Shrimp Macrobrachium hainanense, and Mitten Crab Eriocheir sinensis, with all three species recorded in Sai Kung, Pak Kong and Ho Chung Rivers.

Avifauna

8.4.33 Totally, 64 avifauna species were observed during the surveys, with similar numbers of species recorded at all three Assessment Areas (51, 46, and 49 at Sai Kung and Sha Ha, Pak Kong and Ho Chung respectively). Commonly recorded species at all three sites included Black-necked Starling (Sturnus nigricollis), Chinese Bulbul (Pycnonotus sinensis), Crested bulbul (Pycnonotus jocosus) and Crested Myna (Acridotheres cristatellus). These species are generally associated with disturbed cultivation lands and villages. Twelve species of conservation interest were recorded during the field surveys, mostly in and around the estuaries of Ho Chung and Pak Kong Rivers. Mangrove and marine habitat at Ho Chung in particular were found to support a comparatively large and diverse avifaunal assemblage. Species of conservation interest are described in the following sections.

Ardeids (Herons and Egrets)

8.4.34 Five Ardeid species of conservation interest (Chinese Pond Heron, Ardeola bacchus; Great Egret, Casmerodius alba; Grey Heron, Ardea cinerea; Little Egret, Egretta garzetta; and Night Heron, Nycticorax nycticorax) were recorded in the Assessment Areas, with the highest numbers observed at Ho Chung River Estuary. The large, fairly secure populations of Great Egret, Little Egret and Grey Heron that occur in Hong Kong are considered important in a regional context (Fellowes et al., 2002). Chinese Pond Heron are considered of conservation importance due to locally declining populations. Despite the reduced numbers of this species in Hong Kong, the local population is still large enough to be of regional significance (Carey et al., 2001). Night Heron, although locally common, are considered of conservation concern due to the restricted number of known breeding sites.

8.4.35 The Preliminary Environmental Review (PER) for the proposed works noted that Little Egrets, Great Egrets and Chinese Pond Herons had recently established a roost in riparian vegetation at the downstream section of Pak Kong River. The PER suggested this roost could also be a breeding site (egretry). No egret or heron roosting or breeding activity was observed at Pak Kong River or other Assessment Areas during the surveys conducted for this report.

Raptors

8.4.36 Four raptors of conservation interest (Crested Serpent Eagle, Spilornis cheela; White-bellied Sea Eagle, Haliaeetus leucogaster; Osprey, Pandion haliaetu and Peregrine Falcon, Falco peregrinus) were recorded in the Assessment Areas.

8.4.37 Crested Serpent Eagles are relatively uncommon residents in Hong Kong, with most records from the central New Territories (Carey et al., 2001). A single Eagle was observed on several occasions hunting across cultivation land in the Sai Kung Assessment Area. An additional single record was made at the Pak Kong Assessment Area.

8.4.38 White-bellied Sea Eagles are uncommon residents in Hong Kong. They are considered of regional conservation concern due to the small but stable number of breeding pairs found in coastal areas and offshore islands across Hong Kong (Fellowes et al., 2002). During the current surveys, White Bellied Sea Eagles were observed soaring over marine habitat at the Sai Kung Assessment Area.

8.4.39 One Osprey was recorded feeding over Ho Chung estuary in February 2002. Ospreys are locally common winter visitors to Hong Kong, with occasional records during the summer (Carey et al., 2001). Most records are from the Inner Deep Bay Area. The population in Hong Kong is considered of regional conservation concern, due to the species’ restricted regional occurrence (Fellowes et al., 2002).

8.4.40 One Peregrine Falcon was observed flying over the Sai Kung Assessment Area in December 2002. This species is a relatively scarce resident in Hong Kong, and has been recorded from numerous habitats including coastal, inland and urban areas (Carey et al., 2001). The species is considered of local conservation concern by Fellowes et al. (2002) due to limited number of recorded breeding sites.

Other Birds

8.4.41 A single Lapwing (Vanellus vanellus) was recorded from Ho Chung Estuary in January 2003. Lapwings are irregular and scarce winter visitors to Hong Kong, with most records from the Deep Bay Area (Viney et al., 1994), although occasional records from other sites (including Ho Chung) have been made (Carey et al., 2001). Fellowes et al (2002) consider the species of local conservation concern because of its restricted local distribution.

8.4.42 Red-billed Starling (Sturnus sericeus) is a winter visitor to Hong Kong. Preferred habitats of the starling include open lowland areas (including agricultural land) and coastal mangroves, where they can often be found in large flocks (Viney et al., 1994). Other studies have shown they also use fishpond bunds as foraging sites (Aspinwall, 1997). The species is considered of global conservation concern by Fellowes et al. (2002), and is listed as Near Threatened in the IUCN Red Data Lists (IUCN, 2002). Records of 1-3 birds were made from all three Assessment Areas during the current surveys, and a flock of approximately 50 Red-billed Starling were observed at Pak Kong Village in February 2003.

8.4.43 A pair of Black-tailed Hawfinch (Eophona migratoria) were recorded from a village in the Sai Kung Assessment Area in March 2003. This species is a scarce and localised winter visitor to Hong Kong, with small flocks generally recorded from favoured habitats such as orchards, Fung shui woodland and woodland fragments close to agricultural land (Carey et al. 2001). Records of this species in Hong Kong have been declining through the 1990’s. The decline is thought to result from the over-collection of wild birds outside of Hong Kong for sale as pets (ibid). The species is considered of local conservation concern by Fellowes et al. (2002) because of its restricted distribution in Hong Kong and declining numbers.

Mammals & Herpetofauna

Mammals

8.4.44 Evidence of six mammal species was recorded during the field surveys. These included Wild boar (Sus scrofa), House Shrew (Suncus murinus), and a small group of feral Cattle (Bos taurus).

8.4.45 Three mammal species of conservation interest were recorded in the Assessment Areas. The droppings of Barking Deer (Muntiacus muntjak) were found on woodland fringes in the Sai Kung Assessment Area. Barking Deer are protected under the Wild Animals Protection Ordinance, and are considered of potential regional conservation concern by Fellowes et al. (2002). At Pak Kong, two Dog-faced Fruit Bats (Cynopterus sphinx) were recorded roosting in a Fan Palm Tree (Livistona chinensis) between the river channel and Hiram’s Highway. Cynopterus sphinx is relatively common in some parts of Hong Kong, although it is thought to have declined due to the limited availability of mature roost trees (Ades, 1999). All bat species in Hong Kong are protected under the Wild Animals Protection Ordinance. Scats probably belonging to the Leopard Cat (Prionailurus bengalensis) were recorded on a rural roadside in the Sai Kung Assessment Area. Leopard Cat is listed on CITES Appendix II, is regarded as Vulnerable in the China Red Data Book of Endangered Animals (Wang, 1998), and is protected under the Wild Animals Protection Ordinance.

Herpetofauna

8.4.46 In total, seven amphibian species were recorded from the Assessment Area, with seven species found at both Ho Chung and Sai Kung, and six at Pak Kong. All recorded species are common and widespread in Hong Kong.

8.4.47 Ten species of reptiles were found in the three Assessment Areas, with three species at Pak Kong, four at Sai Kung and five at Ho Chung Assessment Areas. Most of the recorded species have a widespread distribution in Hong Kong. One species recorded from cultivation land at Sai Kung and Pak Kong, the Indo-Chinese Rat Snake (Ptyas korros), is considered of conservation interest. Regional populations of this species are thought to be in drastic decline due to over-collection for human consumption. The large, secure population of this species in Hong Kong is therefore considered important in a regional context. (Fellowes et al., 2002).

Terrestrial Insects

Butterflies

8.4.48 A total of 26 butterfly species were recorded in the three Assessment Areas. Most recorded species are common and widespread in Hong Kong. No rare species were observed, but three locally uncommon species were recorded: Small White (Pieris rapae), Plain Tiger (Danaus chrysippus), and Common Birdwing (Troides Helena). Of these, the Common Birdwing is of most conservation interest, being the only protected invertebrate species in Hong Kong. Troides helena was recorded in cultivation land close to woodland in the Sai Kung Assessment Area in June 2003.

Dragonflies

8.4.49 A total of 18 species of dragonfly and damselfly were recorded in the three Assessment Areas, with 9 species recorded from both Ho Chung and Pak Kong, and 16 species at Sai Kung. All recorded species are relatively common and widespread in Hong Kong.

Marine Habitat

Inter-tidal fauna

8.4.50 Mudflats at Ho Chung and Pak Kong supported typical muddy shore species dominated by molluscan (clams and snails) fauna. Crustaceans, particularly Fiddler Crabs (Uca spp.) and Sesarma bidens were common. In terms of species richness, surveys indicated Ho Chung supported a more diverse epifaunal community (27 species) than Pak Kong (22 species). Faunal composition on the mudflat showed little variation between the dry and wet season.

8.4.51 The sandflat at Sai Kung supported 27 intertidal species dominated by sand snails (Batillaria multiformis). Where the Sha Ha Stream enters the sandflat, a single Fiddler Crab (Uca sp.) and Mudskipper (Periophathalmus cantonensis) were observed next to the culvert in the dry season. These species may have been displaced on to the sandflat from the small stream opening behind the seawall due to works on the lower course of the stream.

Sub-tidal fauna

8.4.52 The benthic fauna at Ho Chung and Pak Kong comprised two major taxonomic groups, i.e. molluscs and polycheates. The bivalve (Anomalocardia squamosa) and polycheate (Cirriformia sp.) were common in the subtidal areas at both Ho Chung and Pak Kong estuaries. The species richness of the sampled subtidal fauna of Ho Chung estuary was slightly higher than that of Pak Kung (8 species compared 6).

8.4.53 At Sai Kung, during the wet season survey, a significant breeding congregation of the starfish Archaster typicus, estimated to number over 100 individuals, was observed. A large black sea cucumber Holothuria leucospilota also occurred at the site.

8.5 Ecological Value

8.5.1 In accordance with the EIAO TM Annex 8 criteria, the ecological importance of recorded habitats has been evaluated in Tables 8.1a - 8.1g below.

Table 8.1a Ecological Value of Sai Kung, Pak Kong & Ho Chung Rivers and Sha Ha Stream

Criteria	Rivers, Streams & Riparian Vegetation
Naturalness	The banks and riparian zones of all three rivers have been extensively modified through channelisation works, clearance for agriculture, road construction and other developments. The rivers are affected by agricultural run-off and other pollutants. Downstream Section of Sha Ha Stream severely impacted by on-going infrastructure works.
Size	Sai Kung, Pak Kong and Ho Chung Rivers are moderate in size (~2-7m in bed width). Sha Ha Stream is small in size (~1-2m in bed width).
Diversity	Sai Kung, Pak Kong and Ho Chung Rivers: moderate. Sha Ha Stream: very low.
Rarity	Orange Peacock Puffer (Takifugu ocellatus) Ehretia acuminata, Grey Heron (Ardea cinerea), Little Egret (Egretta garzetta), Night Heron (Nycticorax nycticorax), Chinese Pond Heron (Ardeola bacchus) recorded from this habitat type. Relatively unmodified lowland rivers are increasingly rare habitats in Hong Kong.
Recreatability	Modified streams and rivers have moderate-high recreatability.
Fragmentation	N/a.
Ecological linkage	Pak Kong and Ho Chung Rivers discharge into Coastal Protection Areas.
Potential value	The potential value is low-moderate.
Nursery ground	Large numbers of juvenile fish recorded in Pak Kong and Ho Chung Rivers.
Age	N/a.
Abundance/ Richness of Wildlife	Low to moderate species diversity.
Ecological value	Sai Kung, Pak Kong and Ho Chung Rivers: Moderate Sha Ha Stream: Very Low

Table 8.1b Ecological Value of Cultivation Lands Recorded in the Assessment Area

Criteria	Cultivation Lands
Naturalness	Man-made habitat.
Size	Moderate.
Diversity	Low plant diversity.
Rarity	Mongolian Dandelion (Taraxacum mongolicum), Indo-chinese Rat Snake (Ptyas korros), Little Egret (Egretta garzetta), Chinese Pond Heron (Ardeola bacchus), Crested Serpent Eagle (Spilornis cheela), Leopard Cat (Prionailurus bengalensis) and Common Birdwing (Troides Helena) recorded from this habitat type.
Recreatability	Habitat easily recreated on suitable low-lying land.
Fragmentation	The habitat is not fragmented.
Ecological linkage	Habitat does not fall within recognised areas of conservation interest.
Potential value	The potential value is low-moderate.
Nursery ground	No record of significant nursery or breeding ground was found in the survey.
Age	N/a.
Abundance/ Richness of Wildlife	Moderate species diversity.
Ecological value	Low-Moderate.

Table 8.1c Ecological Value of Woodland and Fung Shui Woodland in the Assessment Areas

Criteria	Woodland and Fung Shui Woodland
Naturalness	The habitats are largely natural, although disturbed to some extent due to proximity of villages and developed areas.
Size	Woodland patches are small-moderate in size.
Diversity	Moderate-High.
Rarity	Tutcheria championii, Pavetta hongkongensis and Barking Deer (Muntiacus muntjak) recorded from this habitat type.
Recreatability	Low-moderate. Habitat would regenerate naturally over 50-60 years.
Fragmentation	Small Patches found throughout the Assessment Areas.
Ecological linkage	Habitat found partially within Conservations Areas, Coastal Protection Areas and Tsiu Hang Special Area.
Potential value	Moderate.
Nursery ground	No record of significant nursery or breeding ground was found in the survey.
Age	Woodland generally estimated to be at least 50-60yrs old.
Abundance/ Richness of Wildlife	Moderate-High.
Ecological value	Moderate-High.

Table 8.1d Ecological Value of Shrubland in the Assessment Areas

Criteria	Shrubland
Naturalness	The habitats are largely natural, although disturbed to some extent due to proximity of villages and developed areas. Shrubland habitats in Hong Kong are often maintained by frequent hill fires.
Size	small-moderate in size.
Diversity	Low-moderate
Rarity	No rare species recorded from this habitat type.
Recreatability	Moderate. Habitat would regenerate naturally over 15-25 years.
Fragmentation	Small Patches found throughout the Assessment Areas.
Ecological linkage	Habitat found partially within Conservations Areas.
Potential value	Moderate.
Nursery ground	No record of significant nursery or breeding ground was found in the survey.
Age	Shrubland generally estimated to be at least 15-20yrs old.
Abundance/ Richness of Wildlife	Low-Moderate.
Ecological value	Low.

Table 8.1e Ecological Value of Village and Developed Areas in the Assessment Areas

Criteria	Village and Developed Area
Naturalness	Habitat is man-made.
Size	Moderate.
Diversity	Low-moderate.
Rarity	Red-billed Starling (Sturnus sericeus), Black-tailed Hawfinch (Eophona migratoria) and Dog-faced Fruit Bat (Cynopterus sphinx) recorded from this habitat type.
Re-creatability	High.
Fragmentation	N/a.
Ecological linkage	Habitat in close proximity to Conservations Areas, Coastal Protection Areas and Tsiu Hang Special Area.
Potential value	Moderate.
Nursery ground	No record of significant nursery or breeding ground was found in the survey.
Age	N/a.
Abundance/ Richness of Wildlife	Low-moderate.
Ecological value	Low

Table 8.1f Ecological Value of Mangroves in the Assessment Areas

Criteria	Mangrove
Naturalness	Mangroves at Ho Chung and Pak Kong were relatively undisturbed and appeared to be in healthy condition. Some localised greywater discharge was noted as entering Ho Chung mangrove from neighbouring village areas.
Size	Ho Chung: approx 2.5ha ; Pak Kong: approx 1 ha.
Diversity	Ho Chung and Pak Kong mangroves have moderate floristic diversity compared to other mangroves in Hong Kong.
Rarity	Ho Chung and Pak Kong: Great Egret (Casmerodius alba), Grey Heron (Ardea cinerea), Little Egret (Egretta garzetta), Night Heron (Nycticorax nycticorax) Chinese Pond Heron (Ardeola bacchus) recorded from this habitat type.
Re-creatability	Mangrove may be planted.
Fragmentation	There are other mangrove stands relatively nearby within Hebe Haven and elsewhere in Port Shelter.
Ecological linkage	Ho Chung mangrove is partially within a Coastal Protection Area. Pak Kong mangrove is immediately adjacent to a Coastal Protection Area.
Potential value	Mangroves are of conservation interest.
Nursery ground	Mangroves are nurseries for many species
Age	Mangrove trees were mature.
Abundance/ Richness of Wildlife	Moderate.
Ecological value	Ho Chung: High Pak Kong: Moderate

Table 8.1g Ecological Value of Marine Habitat in the Assessment Areas

Criteria	Marine Habitat
Naturalness	Largely natural. Ho Chung and Pak Kong mudflat are subject to disturbance by relatively small-scale clam collector/ combers. Ho Chung mudflat subject to localised greywater discharge from adjacent village. Sai Kung is extensively used for recreational purposes including shore combing
Size	Large
Diversity	Marine habitat supports moderate faunal diversity
Rarity	White-bellied Sea Eagle, Haliaeetus leucogaster recorded from Sai Kung Great Egret (Casmerodius alba), Grey Heron (Ardea cinerea), Little Egret (Egretta garzetta), seagrass (Halophila ovata) recorded from Pak Kong Osprey, (Pandion haliaetu), Lapwing (Vanellus vanellus), Great Egret (Casmerodius alba), Grey Heron (Ardea cinerea), Little Egret (Egretta garzetta), seagrass (Halophila ovata) recorded from Ho Chung.
Re-creatability	Low.
Fragmentation	Marine habitat is not fragmented. Isolated seagrass patch is regarded to be from fragmented population.
Ecological linkage	Ho Chung mudflat is partially within a Coastal Protection Area. Pak Kong mudflat is immediately adjacent to a Coastal Protection Area. Sai Kung marine habitat is partially adjacent to Coastal Protection Area.
Potential value	Ho Chung and Pak Kong may develop conservation interest. It is unlikely that marine habitat at Sai Kung would develop conservation interest.
Nursery ground	Mudflat and seagrass at Ho Chung and Pak Kong may provide nursery habitats for many species. Breeding activity by starfish Archaster typicus was observed at Sai Kung.
Age	N/A.
Abundance/ Richness of Wildlife	Moderate
Ecological value	Ho Chung and Pak Kong: Moderate Sai Kung: Low

8.5.2 Despite channel modification and moderate pollution levels, the Sai Kung, Pak Kong and Ho Chung Rivers were found to support moderately diverse aquatic communities, including some species of conservation interest. Aside from supporting low densities of ardeids, the rivers were not considered of high importance to avifauna, mammals, herpetofauna or insects of conservation interest. Additionally, most lowland rivers in Hong Kong have been subject to various anthropogenic impacts, and relatively undisturbed lowland rivers/streams are therefore becoming increasingly rare. Despite habitat degradation through pollution and channelisation, the three rivers surveyed for this report are amongst the few remaining lowland rivers in Hong Kong that have not been severely impacted by channel modification, water extraction and/or gross pollution. The ecological value of the rivers is therefore rated as moderate.

8.5.3 Sha Ha stream has been severely impacted by on-going infrastructure works. The lower course of the stream was found to flow over exposed soil and is subject to extremely high levels of suspended sediments. The ecological value of Sha Ha Stream was rated as very low.

8.5.4 Cultivation land in the Assessment Areas had been extensively modified by human activities, and supported a relatively low diversity of floral species. However, the habitat was found to support moderately diverse faunal communities, particularly avifauna. Furthermore, several species of conservation interest were recorded from this habitat type. For these reasons, cultivation land in the Assessment Areas was considered of low-moderate ecological value.

8.5.5 Woodland and fung shui woodland in the Assessment Areas were found to be relatively mature, and to support a moderate-high diversity of flora and fauna, including some species of conservation interest. The ecological value of these habitats was therefore considered moderate-high.

8.5.6 Shrubland in the Assessment Areas were found to support a low-moderate diversity of flora and fauna. No species of conservation interest were recorded from this habitat type. The ecological value of this habitat was considered low.

8.5.7 Village and developed areas were generally found to be highly disturbed, had low floral and faunal diversity, and supported few species of conservation interest. These habitats are considered to have low ecological value.

8.5.8 Mangroves in the Assessment Areas were in a healthy condition, were little disturbed and supported a moderate abundance of fauna as well as being feeding habitats for notable avifauna. Ho Chung mangrove was large and was considered to have high ecological value. Pak Kong mangrove was smaller in size and height and was considered to have moderate ecological value.

8.5.9 Marine habitat at Ho Chung and Pak Kong estuary support an abundance of intertidal and subtidal fauna and are feeding habitat for notable avifauna, as well as support a small area of seagrass of conservation concern. Ho Chung and Pak Kong are regularly disturbed by small-scale clam collection activities and are considered to have moderate ecological value. Sai Kung is a relatively busy, disturbed recreational beach area, although it supports moderately abundant common and widespread intertidal and subtidal fauna, none of conservation concern. Marine habitat at Sai Kung is considered to have low ecological value.

8.5.10 With reference to EIAO TM Annex 8 criteria, species of conservation interest recorded in the Assessment Areas are evaluated in Table 8.2 below.

Table 8.2 Species of Conservation Interest Recorded in the Assessment Areas

Common Name	Scientific Name	Status*	Sai Kung	Pak Kong	Ho Chung	Protection Status, Distribution, Rarity and Other Notes**
Flora
Ehretia	Ehretia acuminata	-			x	Rare in Hong Kong
Common Tutcheria	Tutcheria championii	-			x	Restricted distribution in Hong Kong. Protected under Hong Kong Law.
Hong Kong Pavetta	Pavetta hongkongensis	-	x			Common in Hong Kong. Protected under Hong Kong Law.
Mongolian Dandelion	Taraxacum mongolicum	-	x			Rare in Hong Kong.
Spoon Grass	Halophila ovata	-		x	x	Rare in Hong Kong.
Fauna
Fish
Orange Peacock Puffer	Takifugu ocellatus	LC		x	x	Locally restricted breeding sites. Local breeding population declining.
Avifauna
Black-tailed Hawfinch	Eophona migratoria	LC	x			Locally restricted distribution and declining locally.
Chinese Pond Heron	Ardeola bacchus	PRC	x	x	x	Large local population is declining.
Crested Serpent Eagle	Spilornis cheela	(LC)	x	x		Relatively uncommon. Breeding restricted locally.
Great Egret	Casmerodius alba	PRC		x	x	Large, secure population of regional significance.
Grey Heron	Ardea cinerea	PRC		x	x	Large, secure population of regional significance.
Lapwing	Vanellus vanellus	LC			x	Restricted local distribution.
Little Egret	Egretta garzetta	PRC	x	x	x	Large, secure population of regional significance.
Night Heron	Nycticorax nycticorax	(LC)		x	x	Breeding restricted locally.
Osprey	Pandion haliaetus	RC			x	Impacts to population in Hong Kong of regional concern.
Peregrine falcon	Falco peregrinus	(LC)	x			Breeding restricted locally.
Silky Starling	Sturnus sericeus	GC	x	x	x	Regionally important population in Hong Kong.
White Bellied Sea Eagle	Haliaeetus leucogaster	(RC)	x			Breeding population in Hong Kong of regional significance.
Mammals
Barking Deer	Muntiacus muntjak	PRC	x			Protected under HK Law.
Dog-faced Fruit Bat	Cynopterus sphinx	-		x		Protected under HK Law, declining local population.
Leopard Cat	Prionailurus bengalensis	-	x			Listed in CITES App II, listed as vulnerable in Chinese Red Data Book.
Herpetofauna
Indo-Chinese Rat Snake	Ptyas korros		x	x		Regionally declining population.
Terrestrial Insects
Common Birdwing	Troides Helena		x			Protected under HK Law.

*LC – Local Concern (Habitat loss/damage in Hong Kong would pose significant threat to local survival); PRC – Potential Regional Concern (Large, secure populations in Hong Kong are of regional significance); RC – Regional Concern (Habitat loss in Hong Kong would have implications for the survival of the species in South China); PGC – Potential Global Concern (Large, secure populations in Hong Kong are of global significance); GC – Global Concern (Further habitat loss or damage in Hong Kong may have implications for the global survival of the species). Letters in parenthentheses indicate that the assessment is on the basis of restrictedness in breeding and/or roosting sites rather than in general occurrence. Refer to Fellowes et al. (2002) for further explanation of status.

**Information taken from various sources including Corlett et al. (2000), Carey et al. (2001) and Fellowes et al. (2002).

8.6 Identification of Environmental Impacts

8.6.1 Several potential ecological impacts resulting from construction and operation phase activities have been identified:

Construction Phase

· Direct loss or disturbance to lowland stream/river habitats and associated riparian habitats due to channel construction. The approximate length of affected habitats are:

Ø Sai Kung & Sha Ha: 140m of river and 100m of stream

Ø Pak Kong: 144m of river

Ø Ho Chung: 700m of river

· Direct loss of habitats adjacent to drainage improvement works (resulting from widening of existing channels and construction of Sha Ha Diversion Culvert). The approximate areas of affected habitats are summarised in Table 8.3 below:

Table 8.3 Habitats Directly Affected by Channel, Access Road/Path and Other Construction Works

Habitat Type	Sai Kung & Sha Ha	Pak Kong	Ho Chung
Village	-	-	0.77ha
Developed Area	0.14ha	-	-
Cultivation Land	0.4ha	0.1ha	0.33ha
Total*	0.54ha	0.1ha	1ha

*Excluding River/Stream and Riparian Habitats

· Indirect impact to aquatic (freshwater and estuarine) communities downstream of works areas due to increased sedimentation.

· Indirect impacts to habitats and associated fauna adjacent to works areas resulting from increased human activities/disturbance such as construction noise, storage or dumping of construction material and construction site run-off.

Operation Phase

· Potential direct and indirect impacts to aquatic and riparian communities in newly established channels resulting from routine maintenance works such as removal of accumulated sediments and control of vegetation.

· Potential indirect impact to aquatic (freshwater and estuarine) communities due to periodic storm discharges at the portal.

· No operation phase impacts to downstream sections of the existing Sai Kung River are anticipated. Water flow will be maintained in the lower river, only during high flood events would water be diverted through the Sha Ha Culvert.

8.7 Prediction and Evaluation of Impacts

Rivers, Streams & Riparian Vegetation

8.7.1 The primary potential impact resulting from this project would be direct impacts to lowland river habitat. The scale of this impact would be determined largely by the design of drainage improvement works. Key channel design features for the Sai Kung River and Sha Ha Stream, Pak Kong and Ho Chung Rivers are summarised in the following sections:

Sai Kung River & Sha Ha Stream

8.7.2 For the Sai Kung River, a short section of the river (approximately 140m) would be deepened and widened. The base of the improved channel would be lined with natural substrates (e.g., gravel, cobbles and boulders). To re-create existing conditions as closely as possible, substrates found in the existing river section would be used to line the new channel. Substrates lining the improved channel would be arranged to re-create the existing riffle-pool sequence found in the river. The banks of the improved channel would be lined with rock-filled gabion to improve stability. Pits would be provided in the gabion to allow planting of herbaceous riparian vegetation.

8.7.3 Under the proposed works, the existing Sha Ha Stream would be replaced by a covered box culvert.

Pak Kong River

8.7.4 The proposed drainage improvement works at Pak Kong River would be relatively minor, being limited to minor excavation works, construction of retaining walls and replacement of bridges with box culverts at two locations along the river alignment. The existing riverbed and substrates at works areas would be retained.

Ho Chung River

8.7.5 Approximately 700m of the Ho Chung River would be subject to drainage improvement works. Along most of the affected river section, the existing riverbed and substrates would be retained, and works would be limited to widening the river along the southern bank. Newly widened sections of riverbed would be lined with natural substrates (e.g., cobbles and boulders), with the size and arrangement of these substrates selected to complement adjacent areas of the existing riverbed. The substrates would be sourced as far as practicable from materials excavated during the river widening. The majority of the southern bank of the widened channel would be lined with rock-filled gabion. Pits would be provided in the gabion to allow planting of herbaceous riparian vegetation.

8.7.6 Using the basic design parameters described in Sections 8.7.2-8.7.5 for reference, potential ecological impacts to rivers/streams from construction/operational phase activities have been evaluated. Impact assessments are summarised in Tables 8.4a below, and are assessed in more detail in subsequent paragraphs.

Table 8.4a Overall Impact Evaluation to Sai Kung, Pak Kong and Ho Chung Rivers and Sha Ha Stream

Evaluation Criteria	Rivers, Streams & Riparian Vegetation
Habitat quality	Sai Kung, Pak Kong and Ho Chung Rivers: Moderate Sha Ha Stream: Very Low
Species	Moderate diversity of fish Species of conservation interest including: Orange Peacock Puffer (Takifugu ocellatus), Ehretia acuminata, Grey Heron (Ardea cinerea), Little Egret (Egretta garzetta), Night Heron (Nycticorax nycticorax), Chinese Pond Heron (Ardeola bacchus) recorded from these habitats.
Size/Abundance	Direct impacts/disturbance to: Sai Kung & Sha Ha: 140m of river and 100m of stream Pak Kong: 144m of river Ho Chung: 700m of river
Duration	Direct impacts resulting from drainage improvement works at Sai Kung and Ho Chung Rivers would be permanent, although after a period of establishment and re-colonisation (1-3years) newly constructed sections of the river channels are expected to provide a suitable habitat for existing aquatic communities. Impacts to Pak Kong River would be permanent, although they would be limited to two small sections of the river banks, and no substantial long term impacts to aquatic communities are anticipated. Impacts to Sha Ha Stream would be permanent, lasting for duration of the construction and operation phase. Impacts resulting from routine maintenance and storm discharge would occur periodically through the operation phase.
Reversibility	Direct impacts resulting from drainage improvement works to Sai Kung, Pak Kong and Ho Chung Rivers would be permanent, although the improved river channels would provide suitable habitat for existing aquatic communities, and impacts would therefore be reversible. Sha Ha stream would be replaced by a covered box culvert: loss of habitat would be permanent and irreversible. Indirect impacts such as increased sedimentation and noise disturbance would be limited to the construction phase.
Magnitude	Construction Phase (Sai Kung & Ho Chung Rivers): Low-Moderate Construction Phase (Pak Kong River & Sha Ha Stream): Very Low Operation Phase (all rivers and streams): Low
Overall impact conclusion	Sai Kung and Ho Chung Rivers: Low-Moderate Sha Ha Stream: Low Pak Kong River: Very Low

Habitat Loss

8.7.7 During the construction phase, there would be localised disturbance to aquatic and riparian communities at the three rivers and Sha Ha Stream resulting from the drainage improvement works. Impacts to aquatic and riparian communities resulting from this disturbance are evaluated in the following sections.

Aquatic Habitats and Communities

8.7.8 Proposed impacts to aquatic habitats and communities at Pak Kong River are expected to be very low in scale. Works would be limited to two short sections of the river, and the existing riverbed at these locations would be retained.

8.7.9 Directs impacts to Sha Ha Stream are considered low in scale. Although the box culvert proposed to replace the existing stream would not provide a suitable habitat for aquatic communities, the existing stream is small, supports no species of conservation interest, and is already significantly degraded by on-going infrastructure works.

8.7.10 Impacts to aquatic habitats and communities at Sai Kung and Ho Chung Rivers are considered low-moderate in scale only in view of the following factors:

· Drainage improvement works would be limited to downstream sections of the existing rivers, with substantial sections of each river (particularly at Sai Kung River) remaining unaffected by drainage improvement works (Table 8.5 Refers).

· Within the proposed works areas, drainage improvement works would be conducted in sections (approximately 250m in length) along only one bank of the river at a time. Excavation works would be restricted to an enclosed dry section of the river, with containment measures such as bunds and barriers used within the river to minimise the impacts upon the downstream water body. Using this approach to construction works, only localised areas of the river would be subject to disturbance at any one time, and flow would be maintained within the rivers.

· At Ho Chung, excavation works would be limited, and much of the existing riverbed would be retained.

· The use of natural substrates in the improved Ho Chung and Sai Kung River Channels would provide a suitable habitat for existing aquatic communities recorded in the rivers/streams. Following the re-establishment of aquatic habitats, long-term impacts would be relatively minor.

Table 8.5 Proportion of Rivers Affected by Proposed Drainage Improvement Works.

River	Approximate Total Length of River	Length Affected by Proposed Drainage Works	Proportion of River Length Affected by Drainage Works
Sai Kung River	1300m	140m	10.7%
Sha Ha Stream	575m	100m	17.4%
Ho Chung River	1600m	700m	43.8%
Pak Kong River	1320m	144m	11%

8.7.11 The proposed works at the Ho Chung and Pak Kong Rivers would result in disturbance to the fish species of conservation interest, the Orange Peacock Puffer (Takifugu ocellatus). These impacts are of concern as the estuarine reaches of the Ho Chung and Pak Kong Rivers are potential breeding sites for the fish: disturbance to these habitats could lead to a reduction in reproductive success of the local population. Impacts to T. ocellatus at Pak Kong River are anticipated to be very minor, given the small scale of the improvement works and the fact that the existing riverbed will be retained. Impacts to T. ocellatus at Ho Chung River resulting from the proposed works are considered low-moderate in scale. This evaluation is based on the following factors:

· Takifugu ocellatus is mostly recorded from marine habitats. No direct impacts and only very minor indirect impacts to marine habitats are anticipated to result from the proposed works.

· While the proposed drainage improvement works would cause temporary disturbance to some estuarine sections of the Ho Chung River, estuarine habitats downstream of the works areas (in particular the section of Ho Chung River downstream of Hiram’s Highway) would remain largely unaffected by the proposed works. Furthermore, much of the existing riverbed at Ho Chung River would be retained, and only localised areas of the rivers within the proposed works areas would be subject to disturbance at any one time (Section 8.7.10 refers). In view of these factors, it is anticipated some areas of relatively undisturbed estuarine habitat would be available for potential T. ocellatus breeding for the duration of the construction phase.

· Following re-establishment of aquatic habitats in the newly widened channel, Ho Chung River would provide a suitable habitat for existing aquatic communities previously recorded in the river, including T. ocellatus. Long-term impacts to T.ocellatus and other aquatic organisms are expected to be relatively minor.

Riparian Communities

8.7.12 Impacts to riparian communities at Pak Kong River are expected to be very minor. Works would be limited to two short sections of the river where the existing riverbanks and riparian habitats banks are already subject to some modification.

8.7.13 As noted in Section 8.7.9, directs impacts to Sha Ha Stream are considered low in scale. Although the box culvert proposed to replace the existing stream would not provide a suitable habitat for riparian communities, the existing stream is small, supports no species of conservation interest, and is already significantly degraded by on-going infrastructure works.

8.7.14 Overall, impacts to riparian vegetation along the Ho Chung and Sai Kung existing rivers are considered low-moderate in scale. The primary impact resulting from the loss of riparian vegetation would be the reduction of cover, foraging and potential breeding habitats for avifauna, herpetofauna and other terrestrial wildlife. Affected wildlife would include some species of conservation interest (e.g., ardeids) observed along the river channels, although these species were recorded in relatively low densities along the affected sections of existing rivers. Impacts to riparian vegetation would be partially compensated for through the use of rock-filled gabion along the riverbanks, and the provision of pits in the gabion lining for planting of herbaceous riparian vegetation. Additionally, some natural re-colonisation of grasses, herbaceous plants and low shrubs is anticipated along drier sections of the riverbed within the newly constructed channels. The use of gabion lining and establishment of plants within the riverbed would not compensate for the loss of larger shrubs and mature trees along the banks of existing rivers. Further measures to mitigate for these impacts are recommended in Sections 8.8.15-8.8.16.

8.7.15 The alignment of the proposed Ho Chung Channel is constrained by Ho Chung Road and village areas to the north of the existing river: the widened section of the Channel would have to be constructed to the south of the existing river. In this regard, the proposed drainage improvement works would directly and unavoidably affect two small trees and six seedlings of the tree species Ehretia acuminata recorded on the southern bank of the existing Ho Chung River. Given that this species is relatively rare in Hong Kong, this impact is considered moderate in scale.

Indirect Impacts Due to Increased Sedimentation

8.7.16 Construction methods described in Section 2.5 of this report would serve to limit impacts to aquatic communities in the affected rivers/streams due to increased sedimentation. The excavation works for channels would be carried out in the dry season where possible, with construction carried out by land-based plant. Owing to the construction method (with all excavation works carried out in the dry), impacts would be further minimised. Containment measures such as bunds and barriers would be used within the river to minimise the impacts upon the downstream water body.

8.7.17 With these measures in place, sedimentation is expected to have only local and temporary effects on water quality and aquatic ecology. These impacts are therefore considered relatively minor.

Indirect Impacts Due to Construction Phase Disturbance

8.7.18 Impacts to waterfowl and other wildlife using the rivers would result from temporary loss of feeding habitats and disturbance caused by increased human activity and noisy construction phase activities. These impacts are considered minor, as species of conservation interest (e.g., Little Egret Egretta garzetta), were found in relatively low abundance along affected river channels compared to other habitats in the Assessment Areas (e.g., mangrove and marine habitats at Ho Chung Estuary). Furthermore, construction phase disturbance impacts would be temporary in nature, as the newly created drainage channels are expected to provide suitable foraging grounds for waterfowl and other wildlife using the existing river channels.

Operation Phase Impacts

8.7.19 Operation phase activities at the newly created drainage channels would include periodic maintenance works These works are expected to cause only minor disturbance to the channel beds, consisting of desilting, emptying sand traps, clearing vegetation and repairing the natural bed if necessary. As stated in Section 8.8.11, maintenance activities would be phased, ensuring any disturbance to aquatic communities is localised, and areas of undisturbed habitat are maintained at all times

8.7.20 Due to the increased capacity of the improved drainage channels, discharge during peak-flow events (such as after extended periods of heavy rain) could be higher than in the existing channels. Increased discharge could affect aquatic communities, with increased flow rates ‘washing out’ aquatic and riparian plants and animals.

8.7.21 Flooding events in river and stream course is a natural and relatively frequent phenomenon in Hong Kong owing to the monsoonal climate which delivers heavy rains in summer, causing water courses to flow in spate. During spate, aquatic communities are affected due to increased flow rates causing “washing-out” of aquatic and riparian plants and animals. Locally, lotic communities are well-adapted to survive flood spates. For example: many insects with aquatic life-cycle larval stage time the emergence of adult stage before the wet season, therefore avoiding peak flow events. Stream fish also have behavioural adaptations to high flow rate by taking refuge between bottom substrate on the streambed.

8.7.22 Channelisation of the rivers would not be expected to cause significant impact to stream organisms beyond natural impacts under normal summer flood spates. During higher magnitude flood events, flow velocity in the channelised streams with improved drainage capacity would be expected to be greater than existing stream channels. These infrequent and temporary high flow rate conditions are not expected to have long term negative adverse impacts on aquatic communities in the rivers. Impacts on aquatic insects are unlikely to be significant due to their avoidance of high flow conditions. Similarly, high flow rates are unlikely to adversely affect estuarine fish which may temporarily move the short distance downstream into the slower flowing estuary waters. Owing to the natural substrates of the rivers, freshwater stream fish populations would have suitable refuges to escape temporary high flow conditions.

8.7.23 According to the water quality assessment, there is not expected to be significant impact on water quality during flood events. Indirect impacts on mangrove and marine habitat during operation phase flood events are expected to be very low.

Other Habitats

8.7.24 Potential ecological impacts to habitats aside from rivers/streams in the Assessment Areas have been evaluated, are summarised in Tables 8.4b - 8.4g below.

Table 8.4b Overall Impact Evaluation to Cultivation Lands

Evaluation Criteria	Cultivation Lands
Habitat quality	Low-moderate.
Species	No species of conservation interest directly affected by the proposed works.
Size/Abundance	Approximately 0.83ha of cultivation land would be directly impacted.
Duration	Loss of 0.83ha of cultivation land would be permanent. Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Reversibility	Loss of 0.83ha of cultivation land would be permanent. Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Magnitude	Low.
Overall impact conclusion	Low.

Table 8.4c Overall Impact Evaluation to Woodland and Fung Shui Woodland

Evaluation Criteria	Woodland and Fung Shui Woodland
Habitat quality	Moderate-High
Species	No species of conservation interest directly affected by the proposed works.
Size/Abundance	No woodland or Fung Shui Woodland would be directly affected by the proposed works
Duration	Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Reversibility	Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Magnitude	Very Low
Overall impact conclusion	Very Low

Table 8.4d Overall Impact Evaluation to Shrubland

Evaluation Criteria	Shrubland
Habitat quality	Low-Moderate
Species	No species of conservation interest directly affected by the proposed works.
Size/Abundance	No shrubland would be directly affected by the proposed works
Duration	Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Reversibility	Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Magnitude	Very Low
Overall impact conclusion	Very Low

Table 8.4e Overall Impact Evaluation to Village and Developed Areas

Evaluation Criteria	Village and Developed Areas
Habitat quality	Low
Species	No species of conservation interest directly affected by the proposed works.
Size/Abundance	Approximately 0.91ha of village and developed areas would be directly impacted.
Duration	Loss of 0.91ha of habitat would be permanent. Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Reversibility	Loss of 0.91ha of habitat would be permanent. Indirect impacts such as noise disturbance would be largely limited to the construction phase.
Magnitude	Very Low
Overall impact conclusion	Very Low

Table 8.4f Overall Impact Evaluation to Mangrove

Evaluation Criteria	Mangrove
Habitat quality	Ho Chung mangrove: High Pak Kong mangrove: Moderate
Species	No species of conservation interest would be directly affected by the works Minor indirect impact to moderate diversity avifauna community
Size/Abundance	No mangrove habitat would be directly affected by the works
Duration	Indirect impacts such as increased sedimentation and noise disturbance would be limited to the construction phase. Impacts resulting from routine maintenance and storm discharge would occur periodically through the operation phase.
Reversibility	Indirect water quality impacts through sedimentation would be temporary and limited to the construction phase. Impacts resulting from routine maintenance and storm discharge would occur periodically through the operation phase.
Magnitude	Construction Phase: Very Low Operation Phase: Very Low
Overall impact conclusion	Very Low

Table 8.4g Overall Impact Evaluation to Marine Habitat

Evaluation Criteria	Marine Habitat
Habitat quality	Ho Chung and Pak Kong mudflat: Moderate Sha Ha sandflat: Low
Species	No species of conservation interest would be directly affected by the works.
Size/Abundance	No marine habitat would be directly affected by the works.
Duration	Indirect impacts such as increased sedimentation and noise disturbance would be limited to the construction phase. Impacts resulting from routine maintenance and storm discharge would occur periodically through the operation phase.
Reversibility	Indirect water quality impacts through sedimentation would be temporary and limited to the construction phase. Impacts resulting from routine maintenance and storm discharge would occur periodically through the operation phase.
Magnitude	Construction Phase: Very Low Operation Phase: Very Low
Overall impact conclusion	Very Low

Habitat Loss

8.7.25 Direct habitat loss would be limited to small areas of low-moderate ecological value cultivation land and low ecological value village/developed area habitat. No species of conservation interest or areas of recognised conservation interest would be directly affected by the proposed works. These impacts are considered minor.

Indirect Impacts Due to Increased Sedimentation

8.7.26 Potentially, high sediment levels could smother marine organisms found in mangrove and marine habitats, or could cause clogging of feeding or respiratory surfaces. Marine organisms in their early stages of development may be more susceptible to sedimentation impacts. Owing to the construction method, potential water quality impact through release of sediment during construction is expected to be minimal and highly localised. Elevations in sediment levels associated with construction phase works are not expected to have adverse impacts on mangrove and marine habitat and its seagrasses in Ho Chung and Pak Kong estuaries or at Sai Kung. Indirect impacts on the mangrove and marine habitat in the assessment areas due to water quality impact are expected to be very low.

Indirect Impacts Due to Construction Phase Disturbance

8.7.27 Construction phase disturbance to wildlife in habitats adjacent to the works areas would be temporary, and would generally affect low to low-moderate value ecological habitats where few species of conservation interest were recorded.

8.7.28 The Dog-faced Fruit Bat (Cynopterus sphinx) roost at Pak Kong is adjacent to the proposed works area (within 2-3m). The roost lies within a few metres of the busy Hiram’s Highway, demonstrating that the bats are already tolerant of noise disturbance to some extent. However, construction phase noise and increased human activity could further disturb the bats, and in a ‘worse-case scenario’ lead to the abandonment of the roost. This outcome would still be regarded as a relatively minor impact, as the preferred roosting habitat (the tree Livistona chinensis) of this species is relatively common in the Pak Kong Assessment Area. For example, 3-4 large Livistona chinensis are located in the garden centre south-east of the current roost site (approximately 140m from the existing roost). Additionally, there are extensive banana tree stands throughout the Pak Kong Assessment Area (fruit bats are sometimes known to roost in these trees as well, Ades, 1999). It is probable that the bats would simply re-locate alternative roost sites if disturbed.

8.7.29 The Ho Chung Estuary was identified as an important feeding ground for avifauna during surveys conducted for this Report. Noise disturbance to this area resulting from construction phase activities is expected to be minor. The main mudflat and mangrove area at Ho Chung lie approximately 200m from the proposed Ho Chung Works Area. Furthermore, buildings (e.g., Berkley Bay Villas) and other structures south east of the proposed works area would screen the estuary from noise disturbance. For this reasons, noise disturbance from construction phase activities is unlikely to have a notable impact on avifauna feeding in the estuarine area.

Operation Phase Impacts

8.7.30 Operation phase activities at the newly created drainage channels would include periodic maintenance works such as clearance of overgrown vegetation within the channels and de-silting works. Impacts to habitats adjacent to and downstream of the channels resulting from these activities are expected to be very minor due to the temporary and localised nature o f the disturbance.

8.7.31 As discussed in Sections 8.7.20-8.7.23, impacts resulting from storm-water discharge to aquatic and riparian communities including mangrove and marine habitats are expected to be minor.

Impacts to Species of Conservation Interest

8.7.32 Overall, potential impacts to species of conservation interest identified in the Assessment Areas are considered minor. Specific impacts to species of conservation interest are described in Sections 8.7.7-8.7.31 above. Potential impacts resulting from the works are summarised in Table 8.6 below.

Table 8.6 Summary of Potential Impacts to Species of Conservation Interest

Species of Conservation Interest		Construction Phase Impacts		Operation Phase Impacts
Common Name	Scientific Name	Description	Evaluation	Description	Evaluation
Flora
Ehretia	Ehretia acuminate	Two small trees along with several seedlings directly impacted by channel construction	Moderate	No impact.	No Impact
Common Tutcheria	Tutcheria championii	Sufficiently distant (app. 250m) from works area. No impact predicted	No Impact	Sufficiently distant (app. 250m) from works area. No Impact predicted	No Impact
Hong Kong Pavetta	Pavetta hongkongensis	Sufficiently distant (app. 350m) from works area. No impact predicted.	No Impact	Sufficiently distant (app. 350m) from works area. No impact predicted.	No Impact
Mongolian Dandelion	Taraxacum mongolicum	Sufficiently distant (app. 350m) from works area. No impact predicted.	No Impact	Sufficiently distant (app. 350m) from works area. No impact predicted.	No Impact
Spoon Grass	Halophila ovata	Sufficiently distant (app. 250m) from works area, and very low water quality impact expected. Elevations in sediment levels associated with construction phase works are not expected to have adverse impacts on marine habitat and its seagrasses in Ho Chung and Pak Kong estuaries.	Very Low	Sufficiently distant (app. 250m) from works area. No Impact predicted	No Impact
Fauna
Fish
Orange Peacock Puffer	Takifugu ocellatus	Species recorded in lower channel of Pak Kong and Ho Chung Rivers. Due to limited scale of works, impacts at Pak Kong River are expected to be very minor. At Ho Chung River, there would be potential localised disturbance to habitat during construction phase as a result of excavation works, construction of stream banks/bed, and increased sedimentation.	Low-moderate	No substantial impacts anticipated at Pak Kong River. At Ho Chung River, the improved river channel is expected to provide a suitable habitat for this species and other aquatic fauna. Operational impacts would therefore be limited to minor localised disturbance from maintenance works.	Very Low
Avifauna
Black-tailed Hawfinch	Eophona migratoria	Species recorded from village area in Sai Kung Assessment Area. Impacts from construction phase disturbance expected to be very minor.	Low	No Impact	No Impact
Chinese Pond Heron	Ardeola bacchus	Impacts to Chinese Pond Heron using the rivers would result from temporary loss of feeding habitats and disturbance caused by increased human activity and noisy construction phase activities. These impacts are considered minor, as species were found in relatively low abundance along affected river channels compared to other habitats in the Assessment Areas	Low	Created river channels expected to provide a suitable foraging habitat for this species. Operational impacts would therefore be limited to minor localised disturbance from maintenance works.	Very Low
Crested Serpent Eagle	Spilornis cheela	Recorded from cultivation land approximately 400m from the Sai Kung River Works Area. No impact predicted.	No Impact	Recorded from cultivation land approximately 400m from the Sai Kung River Works Area. No impact predicted.	No Impact
Great Egret	Casmerodius alba	Species recorded from estuarine areas at Pak Kong and Ho Chung. Construction phase disturbance impacts expected to be very minor.	Very Low	Species recorded from estuarine areas at Pak Kong and Ho Chung. No operation phase impacts expected.	No Impact
Grey Heron	Ardea cinerea	Impacts to Grey Heron using the rivers would result from temporary loss of feeding habitats and disturbance caused by increased human activity and noisy construction phase activities. These impacts are considered minor, as species were found in relatively low abundance along affected river channels compared to other habitats in the Assessment Areas	Low	Created river channels expected to provide a suitable foraging habitat for this species. Operational impacts would therefore be limited to minor localised disturbance from maintenance works.	Very Low
Lapwing	Vanellus vanellus	Species recorded from Ho Chung Estuary, approximately 200m from the works area. Impacts from construction phase disturbance expected to be very minor.	Very low	Species recorded from Ho Chung Estuary, approximately 200m from the works area. No operation phase impacts expected.	No Impact
Little Egret	Egretta garzetta	Impacts to Little Egret using the rivers would result from temporary loss of feeding habitats and disturbance caused by increased human activity and noisy construction phase activities. These impacts are considered minor, as species were found in relatively low abundance along affected river channels compared to other habitats in the Assessment Areas	Low	Created river channels expected to provide a suitable foraging habitat for this species. Operational impacts would therefore be limited to minor localised disturbance from maintenance works.	Very Low
Night Heron	Nycticorax nycticorax	Impacts to Night Heron using the rivers would result from temporary loss of feeding habitats and disturbance caused by increased human activity and noisy construction phase activities. These impacts are considered minor, as species were found in relatively low abundance along affected river channels compared to other habitats in the Assessment Areas	Low	Created river channels expected to provide a suitable foraging habitat for this species. Operational impacts would therefore be limited to minor localised disturbance from maintenance works.	Very Low
Osprey	Pandion haliaetus	Species recorded from Ho Chung Estuary, approximately 200m from the works area. Impacts from construction phase disturbance expected to be very minor.	Very low	Species recorded from Ho Chung Estuary, approximately 200m from the works area. No operation phase impacts expected.	No Impact
Peregrine falcon	Falco peregrinus	Species recorded flying over Sai Kung Assessment Area. Disturbance impacts expected to be minor.	Very Low	No Impact	No Impact
Silky Starling	Sturnus sericeus	Silky Starlings are found in a variety of lowland habitats, and have no specialised habitat requirements. Starlings potentially disturbed by construction phase activities would therefore be likely to relocate to nearby lowland habitats. Potential disturbance impacts are therefore considered minor.	Very Low	No Impact	No Impact
White Bellied Sea Eagle	Haliaeetus leucogaster	Recorded from marine habitats over 200m from Sai Kung River Works Area. Impacts from construction phase disturbance expected to be very minor.	Very Low	Recorded from marine habitats over 200m from Sai Kung River Works Area. No operation phase impacts expected.	No Impact
Mammals
Barking Deer	Muntiacus muntjak	Droppings recorded from woodland fringe over 250m from Sai Kung works area. Impacts from construction phase disturbance expected to be very minor.	Very Low	No Impact	No Impact
Dog-faced Fruit Bat	Cynopterus sphinx	Construction phase noise and increased human activity could further disturb the bats, and in a ‘worse-case scenario’ lead to the abandonment of the roost. This outcome would still be regarded as a relatively minor impact, as the preferred roosting habitat (the tree Livistona chinensis) of this species is relatively common in the Pak Kong Assessment Area. For example, 3-4 large Livistona chinensis are located in the garden centre south-east of the current roost site (approximately 140m from the existing roost). Additionally, there are extensive banana tree stands throughout the Pak Kong Assessment Area (fruit bats are sometimes known to roost in these trees as well, Ades, 1999). It is probable that the bats would simply re-locate to alternative roost sites if disturbed.	Low-Moderate	No Impact	No Impact
Leopard Cat	Prionailurus bengalensis	Scats recorded over 350m from Sai Kung River Works Area. Impacts from construction phase disturbance expected to be very minor.	Very Low	No Impact	No Impact
Herpetofauna
Indo-Chinese Rat Snake	Ptyas korros	Rat Snakes are common and widespread in Hong Kong with no specialised habitat requirements. Snakes potentially disturbed by construction phase activities would therefore be likely to relocate to nearby areas further from the source of disturbance. Potential disturbance impacts are therefore considered minor.	Very Low	No Impact	No Impact
Terrestrial Insects
Common Birdwing	Troides Helena	Recorded from cultivation land over 150m from Sai Kung Works Area. Impacts from construction phase disturbance expected to be very minor.	Very Low	No Impact	No Impact

Cumulative Impacts

8.7.33 As described in Table 2.1 of this Report, only one Project (RPIS Project No. SK069 – Improvement of Ho Chung Road) has been confirmed at the time of writing to coincide with the proposed drainage improvement works. Improvements to Ho Chung Road would involve resurfacing, excavation, filling and road works adjacent to the Ho Chung river channel. The anticipated programme for the road works is from March 2005-September 2006, which would be concurrent with the Ho Chung Drainage Improvement Works (scheduled to begin in March 2006) for several months. The road works are not anticipated to directly impact high value ecological habitats. However, noisy construction phase activities and increased human presence have the potential to disturb wildlife in adjacent habitats. This would add to general disturbance levels in the area resulting from drainage improvement works.

8.7.34 Overall, cumulative disturbance impacts resulting from the two Projects are expected to have only minor ecological impact for the following reasons:

· Habitats adjacent to the Ho Chung Road comprise largely low ecological value village and developed areas.

· Noise disturbance from the road works are not expected to affect high ecological value habitats and avifauna at the Ho Chung Estuary.

· Cumulative disturbance from the two Projects would be temporary, limited to a period of several months because of differences in construction programmes.

8.8 Mitigation Measures

8.8.1 Following EIAOTM Annex 16 guidelines mitigation measures are proposed in this section to avoid, minimise and compensate for identified ecological impacts.

Avoid

8.8.2 The proposed works would avoid direct impacts to areas of recognised conservation importance in the Assessment Areas including CA, CPA and Special Area/Country Park.

Minimise

8.8.3 Impacts to existing rivers will be avoided and minimized where possible, with the existing riverbed retained where practicable, and river widening kept to the necessary minimum.

8.8.4 At Pak Kong River, the proposed drainage improvement works have been substantially reduced in scale. Originally, the proposed improvement works would have involved excavating and widening approximately 620m of the existing river channel. The proposed works would now only involve relatively minor works at two locations along the river channel, where the existing riverbed would be retained.

8.8.5 The excavation works for channels should be carried out in the dry condition, with construction carried out by land-based plant. Excavation works should be restricted to an enclosed dry section of the river, with containment measures such as bunds and barriers used within the river to minimise the impacts upon the downstream water body. Site runoff should be directed towards regularly cleaned and maintained silt traps and oil/grease separators to minimise the risk of sedimentation and pollution of river water. The silt and oil/grease separators should be appropriately designed for the local drainage and ground conditions. To minimise leakage and loss of sediments during excavation in narrow channels, tightly sealed closed grab excavators should be deployed where material to be handled is wet.

8.8.6 Noise mitigation measures including the use of quiet construction plant and temporary noise barriers (Section 4 of the reports refers) should be implemented to minimise disturbance to habitats adjacent to the works areas. In particular, measures such as noise barriers should be used to minimise disturbance to the bat roost identified close to the Pak Kong works area.

8.8.7 As stated in Section 8.7.15 the drainage improvement works would directly and unavoidably affect two small trees and six seedlings of the rare tree species Ehretia acuminata recorded on the southern bank of the existing Ho Chung River. It is therefore recommended that the trees and seedlings are transplanted to another area within the Ho Chung site boundary before the commencement of construction phase activities (Figure 8.3 gives a suggested location for the receptor site. The exact location for transplantation would be determined by the Landscape Architect/Others who conduct the transplantation). Fencing would be erected around the transplanted trees/seedlings to minimise potential construction phase disturbance.

8.8.8 While there have been numerous instances of successful tree transplantation in Hong Kong, transplantation of the E. acuminata could prove problematic for the following reasons:

· The plants are currently growing on the southern bank of the Ho Chung River, which is relatively steep. Access for the equipment and vehicles required to transplant the two trees may therefore be limited.

· The substrate in which the E. acuminata are rooted is rocky: difficulties may therefore be encountered when trying to form root-balls prior to transplantation.

· Different tree species are known to have different survival rates following transplantation. Because E. acuminata is relatively rare in Hong Kong, the survival rate of this species following transplantation is uncertain.

8.8.9 Due to the factors listed in Section 8.8.8, the overall effectiveness of the E. acuminata transplantation cannot be assured. It is therefore recommended that additional measures are undertaken to mitigate for impacts to E. acuminata: seeds from the existing trees should be collected and propagated. The seeds should be collected from mature fruits (the fruiting period of E. acuminata is from May to September) prior to transplantation, and germinated in containers under suitable conditions. Following germination and growth, the seedlings should be planted at suitable locations within the Ho Chung Works Area. The survival of newly planted seedlings should be monitored. Seed collection, propagation, planting and monitoring of E. acuminata should be undertaken by a suitably qualified botanist/horticulturalist appointed by the Project Proponent. A detailed methodology for these works should be formulated during the detailed design stage of the Project, in consultation with AFCD.

8.8.10 It is anticipated that E. acuminata seed collection and propagation would be relatively successful. Observations from Australia indicate that no special treatment of seeds is necessary to induce germination of this species, and germination is rapid from seeds collected from fresh fruit (BRAIN, 2002). Furthermore, several seedlings were observed around the existing two small E. acuminata trees at Ho Chung River, suggesting that seeds contained in fruits from these trees germinate and grow readily.

8.8.11 Potential operational phase activities would be limited to regular channel maintenance such as de-silting. Impacts to aquatic communities resulting from these activities are expected to be minor. Nevertheless, the following measures are recommended to minimise potential impacts resulting from operational phase activities:

· To minimise sedimentation, de-silting should be limited to the dry season (November-March).

· The implementation of de-silting and other activities that could disturb aquatic fauna should be phased to ensure some areas of relatively undisturbed habitat remain available for resident aquatic fauna at all times.

· Waste material produced during de-silting should be disposed of in a timely and appropriate manner.

8.8.12 Standard good site practice measures should be implemented throughout the construction phase. The measures should include:

· Placement of equipment or stockpile in designated works areas and access routes selected on existing disturbed land to minimise disturbance to natural or moderate-high ecological value habitats.

· Construction activities should be restricted to work areas that should be clearly demarcated. The work areas should be reinstated after completion of the works.

· Waste skips should be provided to collect general refuse and construction wastes. The wastes should be disposed of timely and properly off-site.

· General drainage arrangements should include sediment and oil traps to collect and control construction site run-off.

· Open burning on works sites is illegal, and should be strictly prohibited.

Compensation

8.8.1 Various features have been incorporated into the design of Sai Kung and Ho Chung River improvements to minimise long-term habitat loss resulting from the Project (Section 8.7.1-8.7.5 refers). Following a period of establishment and re-colonisation, the newly created channels are expected to provide a suitable habitat for aquatic communities recorded in the existing rivers.

8.8.2 The improved Ho Chung River is expected to provide a suitable habitat for fish communities previously recorded from the river. To further increase the value of the River for fish communities, it is recommended that small fish ladders are constructed over the weirs along the river channel. Existing weirs within the river currently impede the movement of fish between upstream and downstream sections of the river. The fish ladders would facilitate movement past these obstacles, extending the range of fish communities in both upstream and downstream areas. The detailed design of the ladders would be submitted to AFCD for comment and approval before finalisation.

8.8.3 As noted in Section 8.7.14, the loss of riparian vegetation would be partially compensated for through the use of pits in the gabion walls and natural colonisation of parts of the channel base by grasses, herbs and low shrubs. However, these areas of vegetation within the new channel would not provide adequate compensation for the loss of larger shrubs and trees resulting from the Project. To mitigate for these impacts, extensive planting of trees and other vegetation along the banks of the newly created channels would be implemented (Section 9 refers). These planting would include:

· Standard or heavy standard trees would be planted along the banks of newly created channels. Compensatory tree planting would be implemented on at least a 1:1 ratio.

· Further planting of woodland tree and shrub seedlings would be implemented within areas adjacent to the newly constructed channels.

8.8.4 Compensatory planting should make use of native plant species with flowers/fruits attractive to wildlife.

8.9 Residual Environmental Impact

8.9.1 Residual impacts to Pak Kong River would include the replacement of two previously modified riverbanks sections with retaining walls. Given that the riverbed in these areas would be retained, the small scale of the works and the existing modified nature of the riverbanks, this impact is considered very minor in scale.

8.9.2 The construction of a covered box-culvert would permanently affect about 100m of Sha Ha Stream. This impact is considered relatively minor because of the small size and existing low ecological value of Sha Ha Stream.

8.9.3 Impacts to aquatic habitats at Sai Kung and Ho Chung Rivers directly affected by the proposed works during and immediately after the construction phase are rated low-moderate. However, no major long-term residual ecological impacts to these rivers are anticipated. With the proposed mitigation measures in place, it is expected that aquatic communities found in the rivers would quickly re-colonise the modified drainage channels.

8.9.4 The loss of riparian vegetation at Sai Kung and Ho Chung Rivers would be compensated for through planting of vegetation within pits in the gabion bank lining, natural re-colonisation of the channel base, and tree planting/other landscaping works.

8.9.5 Residual impacts to other habitats resulting from the proposed works would include the loss of approximately 0.83ha of cultivation land and 0.91ha of village/developed area. As the affected habitats are of low or low-moderate ecological value, and no species of conservation interest would be directly affected, these impacts are considered minor.

8.9.6 Other residual impacts would result from periodic maintenance activities conducted through the operation phase, and occasional disturbance from storm-water discharge. As described in Sections 8.7.19 - 8.7.23, and 8.7.30-8.7.31 these impacts are anticipated to be minor.

8.9.7 Overall, residual impacts are considered minor.

8.10 Environmental Monitoring and Audit Requirements

8.10.1 The proper implementation of mitigation measures recommended in Section 8.8 should be audited.

8.10.1 A specific monitoring programme of the Sai Kung and Ho Chung Rivers is recommended. The programme should provide data on the re-establishment of aquatic/riparian communities in the channels, and allow an assessment of the relative success of mitigation measures to be made. Baseline data should be collected 2-3 months before the commencement of the construction phase, with monitoring conducted 3 times a year during the construction phase, and 3 times a year for 3 years after the completion of works. Data collected should include abiotic (e.g., water quality, sediment characteristics) and biotic (e.g., avifauna, macroinvertebrate and fish populations, aquatic, emergent and riparian vegetation) parameters. Reports on the findings of each monitoring trip should be submitted to AFCD for review/discussion. A final report summarising the results of monitoring over 3 years should be prepared to serve as a reference for future projects of this kind. Monitoring should be conducted by a suitably qualified ecologist(s) appointed by the Project Proponent.

8.10.2 The newly constructed Sai Kung and Ho Chung River Channels are expected to provide a similar habitat to the rivers they would replace. It is therefore anticipated that wildlife found in the existing rivers would successfully re-colonise the new channels. However, if the post-construction phase monitoring demonstrates that re-colonisation is unsuccessful the following contingency plan should be implemented:

· Baseline data collected prior to the construction phase should be compared with post-construction phase data. Any substantial differences in habitat characteristics (e.g., water quality, aquatic/emergent vegetation) should be noted.

· The potential cause of differences between pre- and post-construction phase habitat characteristics (e.g., changes in water depth, sediment characteristics) should be identified.

· Measures to further rehabilitate the habitat characteristics of river channels should be implemented (e.g., minor re-profiling of riverbed, planting of riparian/emergent/aquatic vegetation, increasing heterogeneity of substratum).

· Further monitoring of abiotic and biotic parameters should be conducted to determine the relative success of the contingency habitat rehabilitation measures.

8.10.3 Following transplantation of the two Ehretia acuminata trees and approximately six seedlings, and the planting of seedlings germinated from seeds collected from the two trees, regular monitoring of the trees and seedlings should be conducted to check on the health and condition of the plants. Monitoring should cover the 12-month period following transplantation and planting, and be conducted at least twice a month for the first four months after transplantation/planting, and once a month for the remaining eight months. Monitoring should be conducted by a suitably qualified botanist/horticulturalist appointed by the Project Proponent.

8.11 Conclusions

8.11.1 Nine-month ecological surveys covering the wet and dry seasons were undertaken to establish the ecological profile of the Sai Kung & Sha Ha, Pak Kong and Ho Chung Assessment Areas.

8.11.2 The Assessment Areas included several areas (Conservation Areas, Coastal Protection Areas, Country Park/Special Area) of recognised conservation interest.

8.11.3 Seven major habitat types were identified within the Assessment Areas, comprising Rivers/Streams, Cultivation Land, Woodland and Fung Shui Woodland, Shrubland, Developed and Village Areas, Mangrove, and Marine Habitat. Several plant species of conservation interest were found in the Assessment Areas, including one rare tree species (Ehretia acuminata) recorded inside the proposed Ho Chung Works Area.

8.11.4 A total of 64 bird species were recorded in the Assessment Areas during recent surveys, 12 of which are considered of conservation interest. One fish, one snake, one butterfly and three mammal species of conservation interest were also recorded from the Assessment Areas during recent surveys.

8.11.5 The primary direct ecological impact resulting from the Project would be the loss of small sections of moderate ecological value lowland rivers. The proposed works are also anticipated to directly affect several individuals of the rare tree Ehretia acuminata.

8.11.6 Other direct impacts would include the loss of 0.83ha low-moderate value cultivation land and 0.91ha low ecological value village and developed area habitats. Because of the low ecological value of the affected habitats, these impacts are considered relatively minor.

8.11.7 Indirect impacts would be expected to include increased sedimentation in aquatic habitats during the construction phase, and disturbance to wildlife caused by increased human activity and noisy construction phase activities. Sedimentation is predicted to have only temporary and localised impacts to aquatic habitats, and is considered a minor ecological impact. Construction phase disturbance would be temporary, and would largely affect only low and low-moderate ecological value habitats. As such, it is considered a minor ecological impact.

8.11.8 Operation phase impacts are expected to be relatively minor.

8.11.9 Measures to avoid, minimise and compensate for identified ecological impacts have been recommended. These include measures to reduce minor construction phase impacts to aquatic communities resulting from increased sedimentation and disturbance. Additionally, individuals of the rare tree species Ehretia acuminata affected by the proposed works are recommended to be transplanted.

8.11.10 The design of drainage channels proposed to replace Sai Kung and Ho Chung Rivers includes the use of natural substrates for lining newly formed channel beds, recreation of natural riffle/pool sequences, use of rocked filled gabion to line newly constructed river banks, and extensive compensatory planting along the channel banks. With these measures in place, it is expected that aquatic communities found in the rivers would re-colonise the newly constructed drainage channels. No major long-term residual impacts to the rivers are anticipated.

8.11.11 With the implementation of the recommended mitigation measures, ecological impacts resulting from the proposed drainage improvement works are expected to be relatively minor and environmentally acceptable.

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