9. FISHERIES IMPACT

9.1 Introduction

9.1.1.1 The upgrading and expansion of San Wai Sewage Treatment Works (STW) and expansion of Ha Tsuen Pumping Station (the Project) are part of the scheme recommended under the "Review of Yuen Long and Kam Tin Sewerage and Sewage Treatment requirements".

9.1.1.2 The Project covers expanding and upgrading San Wai STW, constructing and operating an emergency outfall culvert to nearby drainage channel, and expanding Ha Tsuen Pumping Station. Figure 1.3 shows the locations of the key project components.

9.1.1.3 The treatment level at San Wai STW will be upgraded to enhance the removal of pollutants in the sewage. Centralised disinfection will be applied to disinfect the effluent from San Wai STW and effluent after secondary treatment from Yuen long STW. Discharge of disinfected effluent will be through the NWNT effluent tunnel to the outfall at Urmston Road. An emergency bypass culvert connecting San Wai STW to Tin Shui Wai Drainage Channel is also proposed to deal with an emergency event when the NWNT effluent tunnel is out of operation.

9.1.1.4 This section presents an assessment of potential impacts to commercial fisheries as a result of this project. The fisheries impact assessment fulfilled the related requirements of the EIA Study Brief, as well as the technical requirements of the Technical Memorandum on the EIA Process (EIAO-TM).

9.1.1.5 The Assessment Area for fisheries impact assessment, as stipulated in the Study Brief, covers the project site of the San Wai STW and its adjacent area of potential impact, as well as the Assessment Area for water quality impact assessment. The Project involves a regular outfall in Urmston Road and an emergency bypass to Tin Shui Wai. Three Water Control Zones (WCZs), which were designated under the Water Pollution Control Ordinance, are covered by the Assessment Area for water quality (i.e. the Deep Bay WCZ, North Western WCZ, and Western Buffer WCZ).

9.1.1.6 A terrestrial Assessment Area for ecology, defined as the area 500m either side of and along the full length of the project boundary, including the San Wai STW, the Ha Tsuen Pumping Station, and the four alternative alignments of the proposed emergency bypass culvert, was surveyed for ecological impact assessment. Fishponds within this Ecology Assessment Area were also surveyed for fisheries impacts.

9.2 Legislation, Policies, Plans, Standards and Criteria

9.2.1.1 Hong Kong SAR Government ordinances and regulations relevant to this fisheries assessment include the following:
· Fisheries Protection Ordinance (Cap. 171) and its subsidiary legislation, the Fisheries Protection Regulations
· Marine Fish Culture Ordinance (Cap. 353) and associated subsidiary legislation
· Environmental Impact Assessment Ordinance (Cap. 499) and associated Technical Memorandum on Environmental Impact Assessment Process

9.3 Methodology

9.3.1 Literature Review

9.3.1.1 A literature review was undertaken to describe the baseline conditions in the Assessment Area, and to identify areas and species of potential fisheries importance which may be affected by the project. Reviewed documents include Government and private sector reports, as well as unpublished information, as follows:
· Port Survey 96/97 conducted for AFD (AFD 1998)
· AFCD annual report

9.3.1.2 The commercial fishery in Hong Kong is composed of capture fisheries and culture fisheries. Port Survey 96/97 (AFD 1998), which provided the most updated data and statistics on inshore capture fisheries in Hong Kong, was consulted to assess capture fisheries impacts, while the AFCD annual reports from 1991/1992 to 1999/2000 were consulted to assess culture fisheries impacts, both marine and freshwater.

9.3.2 Field verification surveys

9.3.2.1 Field verification of the operational status of the fishponds in the Ecology Assessment Area were conducted twice during the study period (18 September 2001 and 19 February 2002). Fisheries operations such as stocking, feeding and harvesting, the presence of fisheries devices such as aerators and anti-cormorant wires, and the maintenance conditions of the facilities along the pond bunds were noted. The status of fishponds (active or inactive) was evaluated based upon management conditions of the ponds, the presence of fish farming materials and/or equipment, and fish farming activities.

9.4 Baseline Conditions

9.4.1 Recognised / Designated Sites of Fisheries Importance

9.4.1.1 As stipulated in Section 3.4.7.3 (ii) of the EIA Study Brief, within the "Assessment Area", special attention should be paid to:
· existing capture fisheries;
· Fish Culture Zone in Ma Wan;
· fishponds in San Wai; and

9.4.1.2 For statistical purposes Hong Kong waters are divided into 189 Fishing Areas. The Assessment Area for fisheries included three WCZs. Each covers a number of Fishing Areas (Figure 9.1).

9.4.1.3 The Deep Bay Water Quality Control Zone covers five Fishing Areas, i.e. Fishing Area 45, 46, 47, 48, and 49. Although Fishing Area 50 is within mainland waters, it is also described here to provide a more complete review of capture fisheries in Deep Bay. North Western WCZ covers 17 Fishing Areas, i.e. Fishing Area 17, 18, 19, 20, 21, 22, 23, 24, 32, 33, 38, 39, 40, 41, 42, 43 and 44. Western Buffer WCZ covers 24 Fishing Areas, 5 of them, however, have only a small portion falling within the Western Buffer WCZ, and are thus not included for the assessment. These are Fishing Areas 96 (Pak Kok), 102 (Luk Chau), 112 (East Lamma Channel), 158 (Kwai Chung), and 160 (Stonecutters Island). The remaining 19 Fishing Areas include Fishing Area 1, 2, 25, 28, 34, 35, 36, 37, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87 and 88. Thus 42 Fishing Areas would be assessed for fisheries impacts caused by this proposed project.

9.4.1.4 There is no Fish Culture Zone lying within 10 km of the Project Area. The nearest FCZ is Ma Wan FCZ which is more than 15 km from the project area and some 10 km away from the Urmston Road outfall. This is the only Fish Culture Zone within the Assessment Area (Figure 9.1).

9.4.1.5 There are 16 fishponds of about 7.9 ha in San Wai (Figure 8.1).

9.4.1.6 Other recognised or designated sites of importance to capture or culture fisheries in the Deep Bay region include oyster culture beds and rafts near Lau Fau Shan. There is no gazetted oyster farming site in Hong Kong. However, this practice has long existed on the intertidal mudflat in Deep Bay, and large areas of the coastline near Lau Fau Shan have been devoted to culture of oysters. In Marine Water Quality (EPD 2000), this area is labelled a Shellfish Culture Ground.

9.4.2 Site Description

9.4.2.1 The project area has no direct contact to any intertidal or marine environment, though it lies close to the southern coastline of inner Deep Bay. Coastal habitats near the regular outfall site are highly disturbed due to previous reclamation works at Pillar Point, Siu Lang Shui and Tap Shek Kok as well as marine traffic and maintenance dredging.

9.4.2.2 The regular effluent outfall is located at Urmston Road inside North Western WCZ, which is located in the western estuarine zone of Hong Kong waters, to the west of the transitional central and oceanic eastern waters (Morton 1990). The emergency bypass culvert will discharge treated effluent into Deep Bay through Tin Shui Wai Drainage Channel when the NWNT effluent tunnel or the Urmston Road outfall is totally out of operation.

9.4.3 Capture Fisheries

9.4.3.1 Recent detailed data on HKSAR capture fisheries in the Assessment Area are taken from Port Survey 96/97 (AFD 1998).

9.4.3.2 Data on capture fisheries include fish production and economic values as stated in Port Survey 96/97 (Table 9.1). Table 9.1 shows the production values in terms of Hong Kong dollars (HK$), adult fish catch (kg) and fry catch (tails) on a per hectare basis as well as the total value for each of the Fishing Areas within the Assessment Area.

9.4.3.3 The combined surface area of the six Fishing Areas within the Deep Bay WCZ is 13,348.83 hectares or 7.3 % of the total fishing area in Hong Kong. The average value of catch per ha for this WCZ was less than one third the Hong Kong average (510.89 vs 1,892.12), while catches of adult fish (tonnes per ha) were only 7% the Hong Kong average (6.59 vs 97.26). There were no fry capture operations reported in the whole of Deep Bay WCZ.

9.4.3.4 The combined area of the 17 Fishing Areas within North Western WCZ is 13,696.39 hectares, or 7.5 % of the total fishing area in Hong Kong. The average value of catch per ha for this WCA was more than 1.5 times the Hong Kong average (3,414.44 vs 1,892.12), while average catches of adult fish (tonnes per ha) were also more than 1.5 times the Hong Kong average (156.73 vs 97.26). The average catch of fry (tails per ha) was much lower than the Hong Kong average (2.80 vs 35.11).

9.4.3.5 The combined surface area of the 19 Fishing Areas inside Western Buffer WCZ is 6,398.50 hectares, or 3.5 % of the total fishing area in Hong Kong. The average value of catch per ha for this WCZ was more than 1.5 times the Hong Kong average (2,876.08 vs 1,892.12), while catches of adult fish (tonnes per ha) were over 80% the Hong Kong average (82.04 vs 97.26). The average catch of fry (tails per ha) was much lower than that of the Hong Kong average (4.79 vs 35.11).

9.4.3.6 The combined surface area of the 42 Fishing Areas inside the Assessment Area is 33,443.72 hectares, or 18.4 % of the total fishing area in Hong Kong. The average value of catch per ha for the whole Assessment Area was higher than the Hong Kong average (2152.5 vs 1,892.12), while catches of adult fish (tonnes per ha) were slightly lower than the Hong Kong average (82.5 vs 97.26). The average catch of fry (tails per ha) was much lower than that of the Hong Kong average (2.06 vs 35.11).

9.4.3.7 Four Fishing Areas in North Western WCZ (Fishing Area 41, 42, 43 and 44) are located close to the regular effluent outfall in Urmston Road. Information on those Fishing Areas is detailed below.

9.4.3.8 As shown in Table 9.1, the area of Fishing Area 41 accounts for 0.32% of the total fishing area of Hong Kong, however, the adult fish catches recorded from these waters only account for 0.18% of the catch of the Hong Kong fishery. This suggests that Fishing Area 41 is not productive. Furthermore, the catches from the fishing area account for only 0.25% of the value of the Hong Kong fishery. This suggests that the catches from the fishing area are not of high value. Out of 189 fishing areas in Hong Kong waters, Fishing Area 41 was ranked by the 96/97 Port Survey as 125th in terms of production value per ha, and 123rd in terms of adult fish production per ha.

9.4.3.9 As shown in Table 9.1, the surface area of Fishing Area 42 accounts for 0.73% of the total fishing area of Hong Kong, however, the adult fish catches recorded from these waters only account for 0.29% of the catch of the Hong Kong fishery. This suggests that this fishing area is not productive. Furthermore, the catches from the fishing area account for only 0.43% of the value of the Hong Kong fishery. This suggests that the catches are not of high value. Out of 189 fishing areas in Hong Kong waters, Fishing Area 42 was ranked by the 96/97 Port Survey as 135th in terms of production value per ha, and 135th in terms of adult fish production per ha.

9.4.3.10 As shown in Table 9.1, the surface area of Fishing Area 43 accounts for 0.45% of the total fishing area of Hong Kong. However, the adult fish catches recorded from these waters only account for 0.37% of the catch of the Hong Kong fishery. This suggests that Fishing Area 43 is not productive. Furthermore, the catches from the fishing area account for only 0.57% of the value of the Hong Kong fishery. This suggests that the catches from the fishing area are not of high value. Out of 189 fishing areas in Hong Kong waters, Fishing Area 43 was ranked by the 96/97 Port Survey as 98th in terms of production value per ha, and 105th in terms of adult fish production per ha.

9.4.3.11 As shown in Table 9.1, the surface area of Fishing Area 44 accounts for 0.25% of the total fishing area of Hong Kong, however, the adult fish catches recorded from these waters only account for 0.08% of the catch of the Hong Kong fishery. This suggests that this fishing area is not productive. Furthermore, the catches from the fishing area account for only 0.08% of the value of the Hong Kong fishery. This suggests that the catches are not of high value. Out of 189 fishing areas in Hong Kong waters, Fishing Area 44 was ranked by the 96/97 Port Survey as 160th in terms of production value per ha, and 142nd in terms of adult fish production per ha.

9.4.3.12 All these four fishing areas reported zero fry production in the 96/97 Port Survey, indicating that they harbour either species of little commercial value or fry in concentrations too low to make fry collection economically viable. All these four fishing areas, except Fishing Area 43 on production value per ha, were ranked lower than 100th in Hong Kong in production value per ha and adult fish production per ha.

9.4.3.13 There are four fishing ports inside the Assessment Area, i.e. Lau Fau Shan, Castle Peak Bay, Ma Wan and Aberdeen.

9.4.3.14 The nearest fishing port to the regular effluent outfall site is at Castle Peak Bay, about 5 km east of the proposed outfall at Urmston Road. The second nearest fishing port is at Ma Wan, which is about 12 km to the east. Two additional fishing ports are sheltered from the regular outfall by the landmass.

9.4.3.15 The nearest fishing port to the emergency outfall is at Lau Fau Shan, just outside the Tin Shui Wai Drainage Channel. The other three fishing ports (Castle Peak Bay, Ma Wan and Aberdeen) are at least 10 km away and sheltered by the landmass.

9.4.3.16 In summary, from Table 9.1 it is apparent that the fishing areas within North Western WCZ are the most productive, followed by Western Buffer WCZ, and with the Deep Bay WCZ least productive on the basis of the catch value per hectare and production per hectare. While for fish fry production, fishing areas inside Western Buffer WCZ have a higher average value than those inside North Western WCZ (4.79 fry/ha vs 2.80 fry/ha). No fry capture operations have been reported from the fishing areas inside the Deep Bay WCZ.

Table 9.1  Data on HKSAR Capture Fisheries in the Study Area (source: AFD 1998)  

1a. The Deep Bay WCZ (= Deep Bay Sector)

1b. North Western WCZ (= North of Lantau Sector)

1c. Western Buffer WCZ (includes Fishing Areas from Western Harbour Sector, Victoria Harbour Sector and South of Hong Kong Sector)

9.4.4 Fish Culture Zones

9.4.4.1 There is no Fish Culture Zone lying within 10 km of the project area in San Wai. The only FCZ within the Assessment Area is Ma Wan FCZ which is over 15 km from the San Wai project area and about 10 km away from the Urmston Road outfall.

9.4.4.2 The 26 gazetted Fish Culture Zones in Hong Kong occupy a sea area of 209 ha. Hong Kong total marine culture production was 1750 tones in 2000, accounting for 9% of the local consumption of live marine fish. However no figures for individual FCZ production are available.

9.4.4.3 Located within the Kap Shui Mun strait which is well-known for its rapid flow rate, Ma Wan FCZ maintains relatively good water quality. In April 1998, widespread toxic red tide algal blooms caused fish kills at many of the FCZs in Hong Kong. The Ma Wan FCZ was reported the least affected of the FCZs and only minimal fish kills occurred (ERM 1998). There were 132 licensed rafts with a total licensed are of 14,557 m2 at Ma Wan FCZ reported in 2000.

9.4.5 Fishponds

9.4.5.1 Inland fishponds in Hong Kong, covering 1060 ha in 2000, are mainly located in the northwest New Territories. 3120 tonnes of freshwater fish, including tilapia, grey mullet, snakehead and catfish, were produced in 2000, accounting for 6% of the local freshwater fish consumption.

9.4.5.2 Deep Bay fish ponds probably peaked in area during the 1970s or 1980s. In recent years, these ponds have been increasingly subject to conversion for other, more lucrative landuses, including open storage. Development projects including roads, railways, flood control schemes and housing developments have also accounted for a certain amount of pond loss.

9.4.5.3 Figure 8.1 of Section 8 shows the distribution and status of the fishponds in the Ecology Assessment Area for the proposed project. Within this area, there are 16 fishponds covering 7.9 ha in San Wai.

9.4.5.4 Fishponds were scattered among urbanised/disturbed habitats within the Study Area. Apparently not all ponds were managed, i.e. no pump was seen and most grassy bunds were not trimmed. However, one pond was seen with domestic ducks while the two to be lost due to expansion and upgrading of San Wai STW were claimed to be active by the owner. The dilapidated condition of duck rearing houses, lack of aerators and fish fodder, and presence dense vegetation on the bunds of these two ponds suggested that management was either entirely lacking or limited in intensity, and that the ponds may only be harvested for domestic consumption of fish. Most of the ponds still had open water, except one that was overgrown with vegetation.

9.4.6 Oyster farming

9.4.6.1 The oyster beds and rafts near Lau Fau Shan are the only marine culture fisheries sites near the project area. Two species of oyster are cultured in Deep Bay: Crassostrea gigas and C. rivularis. Most of the oysters are cultivated from spat collected in Deep Bay itself or imported from other parts of the Pearl River Estuary. The oysters are grown to market size on cultch (or "culch ", a fixed substrate embedded in the mud) on tidal mudflats, or suspended from oyster rafts near the middle of the bay.

9.4.6.2 The oyster industry in Deep Bay has been seriously threatened by the poor water quality in inner Deep Bay. Oyster production has declined considerably in Deep Bay due to high pollution loads. The 1997 oyster harvest from HKSAR oyster beds was estimated at 60 tonnes, compared to 120 tonnes in 1992 (AFD 1992 - 1998) (see Table 9.2). Local oyster farmers produced fresh oyster meat valued at $3.7 million in 1997. These figures represent a 14 percent decrease by weight and a decrease of 16 per cent by value compared with the preceding year (AFD 1992 - 1998). Hong Kong local oyster production has been exceeded by imports from Mainland China and other countries since the 1970s (Binnie 1984).

Table 9.2 Hong Kong Local Oyster Production and Value (source: AFCD annual reports)

9.5 Fisheries Importance and Sensitive Receivers

9.5.1 Fisheries Importance

9.5.1.1 Within Hong Kong waters the highest yields for local fisheries were mainly derived from the eastern and northeastern coasts as indicated in AFCD's Port Survey 96/97. The four sectors with highest yields among the 12 sectors were all located in eastern and northeastern waters of Hong Kong. Western waters were comparatively less productive.

9.5.1.2 As reported in Port Survey 96/97 (AFD 1998), the catches from the Deep Bay sector (roughly equal to the Deep Bay WCZ) were ranked lowest of the 12 fishing sectors in Hong Kong. These figures demonstrate that the Deep Bay sector, which covers Fishing Areas 45, 46, 47, 48, 49 and 50, is of low importance to capture fishing operations in Hong Kong.

9.5.1.3 The catches from North of Lantau sector (roughly equal to the North Western WCZ) were ranked fourth among the 12 fishing sectors in Hong Kong. These figures demonstrate that the North of Lantau sector, which covers Fishing Areas 17, 18, 19, 20, 21, 22, 23, 24, 32, 33, 38, 39, 40, 41, 42, 43 and 33, is of medium importance to capture fishing operations in Hong Kong.

9.5.1.4 The catches from the Western Buffer WCZ were contributed from fishing areas of three different sectors, i.e. Western Harbour, Victoria Harbour and South of Hong Kong Sector, which ranked 5, 6 and 9, respectively, of the 12 fishing sectors in Hong Kong. These figures demonstrate that Western Buffer WCZ, which covers 19 fishing areas, is of medium to low importance to capture fishing operations in Hong Kong.

9.5.1.5 On the basis of the ranking, and records of fisheries operations in the waters covered by the Assessment Area, the Assessment Area as a whole is of medium to low importance to the Hong Kong fishery.

9.5.1.6 The EIAO-TM (Annex 8) states that nursery areas can be regarded as an important habitat type as they are critical to the regeneration and long term survival of many organisms and their population.

9.5.1.7 Although Deep Bay is designated by the Mainland as a Juvenile Fish and Shrimp Protection Area, there is no record of fish fry collection in the fishing areas inside the Deep Bay WCZ. Only 5 out of the 36 fishing areas inside North Western WCZ and Western Buffer WCZ have records of fish fry production. In combination they contributed 68,952 tails of fry, i.e. 1.08% of the Hong Kong total fry production. In light of the large geographic extent of the Assessment Area yet its small contribution to total HKSAR fry production, the Assessment Area is not considered to be an important nursery area for fish.

9.5.1.8 Fishponds at San Wai were ranked as Grade D by the Agriculture, & Fisheries & Conservation Department (AFCD) Categorization of Agricultural Land. The AFCD ranking recorded 13 ha of fishponds at Hung Shui Kiu - Ha Tsuen area (Reference No. 40, covering Fung Kong Tsuen, Tseung Kong Tsuen, Sik Kong Tsuen, Tung Tau Tsuen, Lo Uk Tsuen, San Wai, San Sang Tsuen, Lee Uk Tsuen and Shek Po Tsuen) (AFD 1995). The AFCD categorization stated that most agricultural land in the area has been converted for use as open storage (ibid.). The field survey of the present project verified and confirmed the ranking and description in 1995.

9.5.1.9 Given the small surface area of the fishponds in the area (7.9 ha) and their low intensity or complete lack of management, the importance of inland fishponds in San Wai is considered low to the fishpond culture industry of Hong Kong.

9.5.1.10 The production of oysters from the Deep Bay area has declined in recent years. Oyster farming within the assessment area contributes a small proportion of total oyster consumption in Hong Kong.

9.5.2 Sensitive Receivers

9.5.2.1 Based upon the above review of baseline fisheries conditions in the Assessment Area, the sensitive fisheries receivers which may be affected by the proposed project have been identified as the 42 fishing areas, the Ma Wan FCZ, the fishponds in San Wai, and the oyster farming industry near Lau Fau Shan.

9.6 Impact Identification and Assessment

9.6.1.1 Impact assessment methodology follows the criteria and guidelines for evaluating and assessing fisheries impact as stated in Annex 9 and 17 of the EIAO-TM.

9.6.1.2 Impacts are generally ranked as "minor", "moderate" or "severe", although in a few cases a ranking of "minimal" (less than "minor") may be given. The ranking of a given impact will vary based on the criteria in the EIAO-TM. The major factors giving rise to a ranking are explained in the text.

9.6.1.3 The fisheries impacts of the project components are assessed individually, then cumulatively with other past, ongoing and proposed projects. Where negative impacts are identified, efforts are made to identify feasible mitigation measures which might be developed to reduce the severity of negative impacts. These measures should be described in terms of their scope, programme, feasibility and financial implications during the construction and operation of the project. Finally, the consultants determined whether the proposed mitigation measures, if implemented, could bring the negative impacts of the project and its components within acceptable bounds.

9.6.2 Construction Stage

9.6.2.1 Predominant impacts to fishery operations and resources usually occur through the loss, temporary or permanent, of areas supporting fisheries resources. In the present proposed project, however, there will be no marine or intertidal infrastructure element involved. No temporary or permanent loss of fishing grounds or fish culture sites would result from implementation of the project.

9.6.2.2 Indirect impacts on marine capture and culture fisheries usually attributable to changes in marine water quality. As no marine or intertidal construction works are planned, and the surface runoff effect will be minimal due to the distance from the construction sites to the coastline, there will be no indirect impacts to marine capture and marine culture fisheries during the construction phase. Therefore there will not be any impacts from construction of the present project on marine capture and culture fisheries.

9.6.2.3 For inland fishponds, only two fishponds covering 1.75 ha adjacent to the existing San Wai STW will be occupied as the site for the first and second phases of expansion and upgrading of San Wai STW at the construction stage (Figure 8.3). Tentatively, the programme of the works is from 2004 to 2007. The completion of phase 1 works would be 2 years after the commencement date of the works. The programme for the phase 2 works would be 3 years (at the earliest) after the commencement date of the works but subject to a future review so as to line in with the population build-up rate in the NWNT. These two fishponds would be liable to direct impacts from the project. Other ponds were located distant from the San Wai STW, the Ha Tsuen Pumping Station and also the four alternative alignments of the proposed emergency bypass culvert.

9.6.2.4 Within the site no type of fish culture will be possible during the construction or operation phases. This will constitute a permanent loss of fishponds. The total area of the affected ponds would be 1.75 ha. This figure constitutes a permanent loss of 0.17 % of the 1060 ha of fishponds in Hong Kong (AFCD 2001). These two fishponds, though claimed by the owner to be actively managed, were actually managed to a limited extent as evidenced by the conditions of the pond bunds. Given the small percentage of loss and the limited management level, the impact on inland fishpond culture in Hong Kong from the loss of these two ponds due to the proposed project is ranked as minor.

9.6.2.5 None of the four alternative alignments of the proposed emergency bypass culvert would cause any direct impacts to fishponds. Alternative 4 of the proposed emergency bypass culvert alignment, however, would utilise the existing Lo Uk Tsuen Channel to connect to the Tin Shui Wai Drainage Channel. No additional opening will need to be constructed at the Tin Shui Wai Drainage Channel. The probability of site runoff during the construction stage of the project is thus the least of all alternatives.

9.6.3 Operation Stage

9.6.3.1 Because there are no marine infrastructure components in the present proposed project, there will be no direct impacts to marine capture and marine culture fisheries in operational phase. The indirect impacts could only result from changes in marine water quality.

9.6.3.2 The current poor water quality in Deep Bay as described in the Water Quality section of this report could be partly attributed to the discharge of untreated sewage. The present project will collect and treat domestic sewage in a large portion of the catchment area of Deep Bay, and will then divert the treated effluent away from Deep Bay.

9.6.3.3 The treatment level at the San Wai STW will be upgraded. One of the options is upgraded from the current preliminary treatment level to Chemically Enhanced Primary Treatment (CEPT) plus disinfection. The treatment capacity will also be expanded to serve a much larger area. Domestic sewage from a population of nearly 1,000,000 at 2016 will be collected and treated at the San Wai STW and discharged to Urmston Road. This effluent would otherwise be discharged into Deep Bay with a lower level of treatment. Enhanced treatment combined with discharge to Urmston Road rather than Deep Bay will have a positive impact to the water quality in Deep Bay, which in turn will benefit capture fisheries and oyster farming.

9.6.3.4 The oyster industry in Deep Bay, as described above, has been seriously threatened by the poor water quality in inner Deep Bay and oyster production has declined considerably. After the implementation of this project, the water quality in the major part of Deep Bay would be improved. As discussed in Section 5 of this report, there would be different levels of reduction in the E.coli levels at water quality indicator points DM3, DM4 and DM5 (DM3: from 208 count/100mL to 196 count/100mL; DM4: from 155 count/100mL to 111 count/100mL; and DM5: from 491 count/100mL to 41 count/100mL). This project is thus considered to have positive effects on oyster farming in Deep Bay.

9.6.3.5 The sewage treatment level for the proposed expanded and upgraded San Wai STW will be significantly improved from primary treatment to Chemically Enhanced Primary Treatment (CEPT) plus disinfection. The water quality modelling carried out for this project concluded that the proposed enhanced treatment would improve water quality in Urmston Road. The water quality modelling results showed that there would be a dramatic decrease in E.coli levels, due to the disinfection treatment process, at two closest EPD marine water quality monitoring stations (from 407 count/100ml to 23 count/100ml at NM5 and from 49 to 6 at NM3). This would be a significant improvement in water quality and would have positive effects on the health of marine organisms including capture fisheries species and marine culture fish species.

9.6.3.6 Changes in other water quality parameters at the two stations would be generally positive, except unionised ammonia. Unionised ammonia (from 0.00358 mg/l to 0.00363 mg/l at NM5 and from 0.00267 to 0.00268 at NM3) are expected to increase slightly. The changes would be very small. Urmston Road, however, is located in the western opening of the channel formed by the landmass of the western New Territories and Lantau Island. This channel is subject to strong tidal flushing effects four times a day. The tidal currents could effectively dilute the minor increases of unionised ammonia levels in the effluent. No significant negative impacts on marine biota are expected from the predicted increases in concentrations of unionised ammonia.

9.6.3.7 Given the distance from the Urmston Road outfall to Ma Wan and the rapid flow rate at Kap Shui Mun strait, the dilution effect on the effluent is predicted to be effective. Impacts on Ma Wan FCZ from the increase of these two parameters for water quality would be expected to be insignificant.

9.6.3.8 There will be a permanent loss of about 1.75 ha of fishponds during the operational phase.

9.6.4 Emergency Discharge

9.6.4.1 Emergency plans for breakdown of the system are essential elements in all sewage treatment facilities. For sewage treatment facilities of large capacity, emergency discharge is the most feasible option to avoid uncontrolled overflow of raw or treated sewage in the catchment area. There are three emergency discharge scenarios for the present project as summarised in Table 9.3. Other than the scenario with the break down of the NWNT tunnel or the Urmston Road outfall, i.e. scenario (ii), the other emergency discharge scenarios for the existing and the future arrangements are similar.

Table 9.3  Emergency Discharge Scenarios

9.6.4.2 With reference to the discussion in Section 1.2 of this report, under the current situation, in the emergency event when the NWNT effluent tunnel or the Urmston Road outfall is out of operation, no matter whether San Wai STW is still in function or not, raw sewage will be discharged directly from the Ha Tsuen Pumping Station into the Tin Shui Wai Drainage Channel and then to Deep Bay, as the NWNT effluent tunnel is the only path for San Wai STW to dispose treated effluent.

9.6.4.3 In order to reduce the chance of discharging raw sewage into Tin Shui Wai Drainage Channel and hence Deep Bay, an emergency bypass culvert, in the form of box culvert, will be constructed from San Wai STW to nearby drainage channel as part of this project. Under the emergency event when the NWNT effluent tunnel or the Urmston Road outfall is out of operation (scenario(ii)), raw sewage from the Ha Tsuen Pumping Station will still be treated at the San Wai STW and then discharged via the proposed emergency bypass culvert to nearby drainage channel and then to Tin Shui Wai Drainage Channel and Deep Bay. With this enhancement measure, the effluent discharged to Tin Shui Wai Drainage Channel and Deep Bay under the emergency event when the NWNT effluent tunnel or the Urmston Road outfall is out of operation will be treated effluent instead of raw sewage. The associated environmental impacts would certainly be lower when compared with the current arrangement.

9.6.4.4 In scenario (ii), the emergency discharge would be treated effluent. Given the treatment level of the effluent, the influence on Deep Bay would be limited. It is anticipated that the longest emergency repairing and maintenance works would be for the NWNT tunnel which could take up to 12 days. A worst case would therefore be taken for all emergency scenarios assuming that the emergency discharge duration would be 12 days. If CEPT plus disinfection were adopted for San Wai STW, there would be no significant deviations from the water quality conditions during normal operation (see Figures 5.21, 5.22, 5.31 & 5.32). This indicates that the introduction of disinfection in the treatment process would significantly minimise the water quality impacts in terms of the increase in E.coli for the emergency discharge case.

9.6.4.5 The protection of Deep Bay from raw sewage is thus significantly increased as the discharge of raw sewage into Tin Shui Wai Drainage Channel and hence Deep Bay would only occur when both the NTNW effluent tunnel/Urmston Road outfall and the San Wai STW are out of operation, or the breakdown of Ha Tsuen Pumping Station (scenario (iii)). Scenario (iii) might have temporary adverse impacts on water quality in Deep Bay. The severity of the impacts would depend upon the duration of emergency discharging, which is expected to be short and the chance of discharge is also very remote. Elevation of E.coli count, TIN and UIA levels were observed immediately after the occurrence of emergency discharge. The influence on water quality at water quality indicator points Tsim Bei Tsui (the nearest water quality sensitive receiver to the outlet of Tin Shui Wai Drainage Channel), DM1, DM2, DM3 and Pak Nai declined with increasing distance. The core area of the two forms of oyster farming in Deep Bay, including intertidal oyster beds and subtidal oyster rafts, is close to the DM3 location. The emergency discharge point of Tin Shui Wai Drainage Channel is several km away from DM3. As shown in Section 5 of this report (see Figures 5.19, 5.23 & 5.25), the E.coli, TIN and UIA levels in DM3 indicated that the influence from emergency discharge were not significant. The levels of these parameters in all indicator points, however, reduced rapidly after the termination of emergency discharge. The E.coli levels decayed rapidly and restored to the normal operation conditions shortly after the termination of discharging (maximum 12 days). In another 8-10 days the TIN and UIA levels also dropped to levels approximating the normal operation conditions. Given the insignificant changes, short period of discharging, and quick self-recovery of the water quality parameters, no impact on oyster farming operation from the emergency discharges was expected from this scenario.

9.6.4.6 Nonetheless, since the commissioning of the existing San Wai STW, the Ha Tsuen Pumping Station, and the NWNT effluent tunnel and Urmston Road outfall more than 10 years ago, it has not ever happened that the NWNT effluent tunnel or Urmston Road outfall was out of operation. The chance of both elements of the system (NWNT tunnel and San Wai STW) out of operation at the same time is even more remote. Besides routine monitoring, inspection, and maintenance to ensure satisfactory working condition of the system, the following have been and will be applied to the Ha Tsuen Pumping Station to further reduce the chance of system failure:

· Standby pumps and screens to facilitate maintenance and repair of equipment;
· Back-up power in the form of dual power supply;
· 24-hour manned pumping station; and
· Hand-cleaned bar screen at overflow bypass to prevent discharge of floating solids.

With all these measures, discharging raw sewage into the Tin Shui Wai Drainage Channel is in fact very unlikely to happen.

9.6.4.7 In scenario (i), the discharge point of raw sewage is outside Deep Bay, the entire affected water body is larger than Deep Bay. The flushing effect at Urmston Road and the dilution of the sewage in this larger water body could reduce the impacts. The TIN and UIA levels in Deep Bay for the emergency discharge case and the normal discharge case (for San Wai STW upgraded to CEPT plus disinfection) were similar without significant differences. The E.coli levels, however, were remarkably higher, ranging from 10x 103 count/100mL at water quality monitoring station NM5 to 14x103 count/100mL at Urmston Road.

9.6.4.8 Though in scenario (i) the TIN and UIA levels would be similar with those before emergency discharge, fisheries resources in Urmston Road would be subject to higher levels of E.coli count. High E.coli count indicates a higher chance of occurrence of pathogens in the water. Exposure to pathogens for a long time period might increase the chance of infection and thus affect the long-term health of marine organisms including capture fisheries species. In the present case, however, given that the E.coli levels would restore to the normal operation conditions shortly after the termination of discharge, the time period of high E.coli levels would be expected to be less than 12 days even under the worst case. Influences on the health conditions of fisheries resources in Urmston Road are thus not expected.

9.6.4.9 As discussed above, the frequency of occurrence of emergency discharge is very low. There have not been any emergency discharges from Ha Tsuen Pumping Station and San Wai STW since their commissioning over a decade ago. All emergency discharge scenarios would be episodic and short-term. Furthermore, the proposed project could help to reduce the pollution loadings in Deep Bay. The improvement in water quality would make Deep Bay have a higher assimilation capability for organic materials, no matter in the form of treated effluent as in scenario (ii), or raw sewage as in scenario (iii). The long-term water quality improvement in Deep Bay and Urmston Road would be a more significant factor for capture fisheries and mariculture than the episodic accidents which would be diluted and naturally decomposed. Though water quality might decline during the emergency discharge period, based upon the low potential of the emergency discharges and the rapid restoration after the termination of discharges, the fisheries impact is ranked as minor.

9.6.4.10 Other than the precaution measures listed above for Ha Tsuen Pumping Station, it is recommended that a contingency plan should be developed at the detailed design stage of this project to deal with the emergency discharges that may occur during the operational stage of the project. It is recommended to include the following items in the contingency plan:

· Locations of the sensitive receivers in the vicinity of the emergency discharges at Deep Bay and Urmston Road and the potential impacts on them;
· A list of relevant government bodies to be informed and to provide assistance in the event of emergency discharges. Information on key contact persons and telephone numbers should be included;
· Reporting procedures required in the event of emergency discharges; and
· Procedures listing the most effective means in rectifying the breakdown of San Wai STW, NWNT Tunnel or Ha Tsuen Pumping Station in order to minimise the discharge duration.

9.6.5 Cumulative Impacts

9.6.5.1 Cumulative impacts to Deep Bay capture fisheries and oyster culture would result from other projects in the Deep Bay area such as Shenzhen Western Corridor project, Deep Bay Link, the Waste-to-Energy Facilities.

9.6.5.2 EPD is considering a potential Waste-to-Energy Facilities (WEF) on the existing ash lagoons to the east of the WENT Landfill. It might also have water quality implications due to operational phase marine traffic. The proposed site for WEF, however, is an existing ash lagoon encircled by existing artificial seawalls. No additional reclamation will be required for the site formation of WEF. Marine transportation for that project will also utilise the existing WENT Landfill pier. Although an increase of marine traffic would result during the operation stage of WEF, the disturbance caused would be very localised and short-term. There should be no significant elevation of suspended solid levels in seawater caused by the proposed WEF.

9.6.5.3 Deep Bay Link is a land-based project. Release of construction site runoff into Deep Bay may cause cumulative impacts with the San Wai STW project. Construction site runoff could be effectively controlled through the implementation of suitable mitigation measures including provision of site drainage systems and sedimentation facilities, routine monitoring of the effluent discharge quality and environmental audit. Generation of wastewater and sewage, and accidental spillage of toxic substances during the construction period could also be controlled by providing chemical toilets and/or wastewater treatment facilities, off-site disposal of wastewater/sewage and establishment of a spill response plan. The potential cumulative water quality impacts due to the Deep Bay Link project are expected to be low.

9.6.5.4 Another planned project in Deep Bay is a proposed bridge across Deep Bay as part of the Shenzhen Western Corridor project. The water quality assessment results indicate that there will be very limited changes in water quality and hydrodynamics.

9.6.5.5 The expansion and upgrading of San Wai STW project is expected to cause positive effect on water quality in Deep Bay and also in Urmston Road. No cumulative impacts are predicted from these projects.

9.6.6 Summary

9.6.6.1 From the information presented above, no adverse fisheries impact associated with the proposed project is expected. An evaluation of the impact in accordance with the EIAO-TM Annex 9 is presented in Table 9.4.

Table 9.4  Evaluation of fisheries impacts in accordance with EIAO-TM Annex 9

9.7 Mitigation Measures

9.7.1.1 In accordance with the guidelines in the EIAO-TM on fisheries impact assessment the approaches to mitigating impacts to fisheries, in order of priority, are avoidance, minimising, and compensation. At each stage, residual impacts should be re-assessed to determine whether there is a need to proceed to the next stage of mitigation.

9.7.1.2 No adverse temporary or permanent impacts of the proposed project to capture fisheries resources in the Assessment Area would be expected. No mitigation measure would be required.

9.7.1.3 No adverse temporary or permanent impacts of the proposed project to the existing oyster rafts near Lau Fau Shan are expected. No impact mitigation would be required.

9.7.1.4 No temporary or permanent impacts of the present project to the Ma Wan FCZ would be expected. No impact mitigation would be required.

9.7.1.5 Permanent impacts of this project to fish culture in fishponds in San Wai would be minor. No impact mitigation would be required.

9.7.1.6 Operation phase water quality, as shown in the water quality assessment would be acceptable, and thus would constitute no impact on fisheries. No impact mitigation would be required.

9.7.1.7 An emergency bypass culvert is proposed under this project as an enhancement measure to the existing system to reduce the chance of discharging raw sewage to Deep Bay under certain emergency situation.

9.7.1.8 Cumulative impacts predicted to arise from the proposed project in conjunction with concurrent projects are not expected to result in greater adverse impacts to fisheries sensitive receivers than would impacts arising from the concurrent projects independently.

9.8 Fisheries Monitoring and Audit

9.8.1.1 Impacts during construction and operation of the project would be monitored through an environmental monitoring and audit (EM&A) programme on water quality that is specified in the EM&A Manual. As permanent impacts to the fishery are predicted to be insignificant, except that to fishponds which is minor, the development of a monitoring and audit programme to assess the effects of the proposed project on commercial fisheries is not considered necessary.

9.8.1.2 Construction and operation of the project would include constraints which act as appropriate mitigation measures to control environmental impacts to within acceptable levels. Monitoring and audit activities designed to detect and mitigate any unacceptable impacts to water quality will also serve to protect against temporary unacceptable impacts to fisheries resources.

9.9 Conclusion

9.9.1.1 Deep Bay is facing long-term pollution problems which threaten the sensitive ecosystem in Deep Bay. HKSAR Government is planning to substantially reduce pollution loadings in Deep Bay. Under the Yuen Long/Kam Tin Sewerage Master Plan, sewage networks will be provided to unsewered villages and new developments, and sewage effluents from Yuen Long and Kam Tin will be transported out of Deep Bay to the better flushed water in Urmston Road for disposal (EPD 2001). The proposed project is an important component of the Plan.

9.9.1.2 This assessment provides an outline of the fisheries baseline for the area, an initial assessment of likely fisheries impacts from project construction and operation, and preliminary options for impact mitigation.

9.9.1.3 A review of existing information supplemented by the results of recently undertaken field surveys on commercial fisheries resources located within and around the Study Area has confirmed that the Assessment Area supports fisheries resources that are neither abundant nor of high value in comparison to resources in other fishing areas of Hong Kong.

9.9.1.4 Potential impacts to fisheries resources and operations may arise from permanent loss of fishponds, and changes in water quality. Due to the small percentage compared to the overall resources in Hong Kong, permanent losses of fisheries resources due to the project are predicted to cause minor impacts to HKSAR fisheries. As changes in water quality would be mostly positive, adverse impacts to fisheries resources are not predicted. In the receiving WCZ (North Western WCZ) the much higher tidal flushing rate would effectively dilute and disperse the pollutant concentrations that would occur at higher levels in the effluent discharged from the expanded and upgraded San Wai STW.

9.9.1.5 An emergency bypass culvert, in the form of box culvert, will be constructed from San Wai STW to nearby drainage channel as part of this project. This culvert will largely reduce the chance of discharging raw sewage into Deep Bay. Under the current emergency situation, raw sewage will be discharged directly from the Ha Tsuen Pumping Station into the Tin Shui Wai Drainage Channel and then to Deep Bay when the NWNT effluent tunnel or the Urmston Road outfall is out of operation. The proposed project will provide an alternative pathway for San Wai STW to dispose treated effluent. With this enhancement measure, the effluent discharged to Tin Shui Wai Drainage Channel and Deep Bay under the emergency event when the NWNT effluent tunnel or the Urmston Road outfall is out of operation will be treated effluent instead of raw sewage. The associated environmental impacts would certainly be lower when compared with the current arrangement.

9.10 References

Agriculture & Fisheries Department (AFD). 1992-2001. Departmental Annual Report. Agriculture & Fisheries Department, Hong Kong Government.
Agriculture & Fisheries Department (AFD). 1995. Categorization of Agricultural Land. (Revised 1995.) Agriculture & Fisheries Department, Hong Kong Government.
Agriculture & Fisheries Department (AFD). 1998. Port Survey 96/97. Summary Table. Prepared by Capture Fisheries Division.
Binnie & Partners (Hong Kong) and Shankland Cox (Binnie). 1984. Tin Shui Wai Development. Environmental Impact Assessment of Land Preparation Aspects. Draft Evaluation Report October 1984.
Environmental Protection Department (EPD). 2001. Marine Water Quality in Hong Kong in 2000. Results for 2000 from the Marine Monitoring Programme of the Environmental Protection Department. Printing Department, Hong Kong.
ERL (Asia) Ltd 1989. Deep Bay Guidelines
Irving, R. and B. Morton. 1988. A Geography of the Mai Po Marshes. Hong Kong University Press, Hong Kong.
Mouchel Asia Ltd. 1997. Feasibility Study for Additional Cross-Border Links Stage 2: Investigations on Environment, Ecology, Land Use Planning, Land Acquisition, Economic/Financial Viability and Preliminary Project Feasibility/Preliminary Design. Water Quality Impact Assessment Review Paper. Prepared for Planning Department, HK SAR Govt. Report dated Dec. 1997.
Mouchel Asia Ltd. 1998. Water Quality Impact Assessment. Working Paper 2. (Deep Bay Crossing and Lingdingyang Bridge) Feasibility Study for the Additional Cross Border Links: Stage 2 Investigations on Environment, Ecology, Land Use Planning, Land Acquisition, Economic/Financial Viability and Preliminary Project Feasibility/Preliminary Design. Prepared for Planning Department, HKSAR Govt. Dated Dec. 1998.
Mouchel. 1999. Final Ecological Impact Assessment, Working Paper WP3. Feasibility Study for Additional Cross-Border Links Stage 2: Investigations on Environment, Ecology, Land Use Planning, Land Acquisition, Economic/Financial Viability and Preliminary Project Feasibility/Preliminary Design. W. Prepared for Planning Department, HK SAR Govt. Report dated Dec. 1999.