Statement of Water Quality Objectives (North Western Water Control Zone) (Chapter 358X)

STATEMENT OF WATER QUALITY OBJECTIVES (NORTH WESTERN WATER CONTROL ZONE) CHAPTER 358X LONG TITLE Empowering section VerDate:30/06/1997 (Cap 358 section 5) [28 February 1992] (L.N. 39 of 1992) SECT 1 VerDate:30/06/1997 The water quality objectives set out in column 1 of the Schedule are established for those parts of the North Western Water Control Zone set opposite those water quality objectives in column 2. (Enacted 1992) SECT 2 VerDate:30/06/1997 In this Statement "Bathing Beach Subzone" means (a) a bathing beach that is specified in the Fourth Schedule to the Public Health and Municipal Services Ordinance (Cap 132) and situated in the North Western Water Control Zone; and (b) the bathing beach at Lung Kwu Tan, which is delineated on a plan marked NWWCZ/LK, signed by the Secretary for Planning, Environment and Lands on 6 November 1991 and deposited in the Land Registry, Victoria; (8 of 1993 s. 30) "Castle Peak Bay Subzone" means an area delineated as such on the Map; "Map" means a series of maps comprising 5 sheets and marked from NWWCZ 1 to NWWCZ 5, signed by the Secretary for Planning, Environment and Lands on 6 November 1991 and deposited in the Land Registry, Victoria; (8 of 1993 s. 30) "marine waters" means all waters below the high water mark within the boundary of the North Western Water Control Zone; "other inland waters" means inland waters other than those in the Tuen Mun (A), Tuen Mun (B) and Tuen Mun (C) Subzones; "Secondary Contact Recreation Subzone" means an area delineated as such on the Map, except where the area is more specifically designated as a bathing beach; "Tuen Mun (A) Subzone" means that part of the catchment of the Tuen Mun River which is delineated and marked TM(A) on the Map; "Tuen Mun (B) Subzone" means that part of the catchment of the Tuen Mun River which is delineated and marked TM(B) on the Map; "Tuen Mun (C) Subzone" means that part of the catchment of the Tuen Mun River which is delineated and marked TM(C) on the Map; "Water Gathering Ground Subzone" means an area delineated as such on the Map. (Enacted 1992) SCHEDULE VerDate:30/06/1997 [section 1] Water Quality Objective Part or Parts of Zone A. AESTHETIC APPEARANCE (a) Waste discharges shall cause no objectionable odours or discolouration Whole zone of the water. (b) Tarry residues, floating wood, articles made zone of glass, plastic, Whole zone rubber or of any other substances should be absent. (c) Mineral oil should not be visible on the surface. Surfactants should Whole zone not give rise to a lasting foam. (d) There should be no recognisable sewage-derived debris. Whole zone (e) Floating, submerged and semi-submerged objects of a size likely to Whole zone interfere with the free movement of vessels, or cause damage to vessels, should be absent. (f) Waste discharges shall not cause the water to contain substances which Whole zone settle to form objectionable deposits. B. BACTERIA (a) The level of Escherichia coli should not exceed 610 per 100 mL, Secondary Contact calculated as the geometric mean of all samples collected in a calendar Recreation year. Subzones (b) The level of Escherichia coli should be less than 1 per 100 mL, Tuen Mun (A) calculated as the running median of the most recent 5 consecutive samples and Tuen Mun (B) taken at intervals of between 7 and 21 days. Subzones and Water Gathering Ground Subzones (c) The level of Escherichia coli should not exceed 1000 per 100 mL, Tuen Mun (C) calculated as the running median of the most recent 5 consecutive samples Subzone taken at intervals of between 7 and 21 days. and other inland waters (d) The level of Escherichia coli should not exceed 180 per 100 mL, Bathing Beach calculated as the geometric mean of all samples collected from March to Subzones October inclusive. Samples should be taken at least 3 times in one calendar month at intervals of between 3 and 14 days. C. COLOUR (a) Waste discharges shall not cause the colour of water to exceed 30 Tuen Mun (A) Hazen units. and Tuen Mun (B) Subzones and Water Gathering Ground Subzones (b) Waste discharges shall not cause the colour of water to exceed 50 Tuen Mun (C) Hazen units. Subzone and other inland waters D. DISSOLVED OXYGEN (a) Waste discharges shall not cause the level of dissolved oxygen to fall Marine waters below 4 mg per litre for 90% of the sampling occasions during the whole year; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1 m below surface, mid-depth and 1 m above seabed). In addition, the concentration of dissolved oxygen should not be less than 2 mg per litre within 2 m of the seabed for 90% of the sampling occasions during the whole year. (b) Waste discharges shall not cause the level of dissolved oxygen to be Tuen Mun (A), less than 4 mg per litre. Tuen Mun (B) and Tuen Mun (C) Subzones, Water Gathering Ground Subzones and other inland waters E. pH (a) The pH of the water should be within the range of 6.5-8.5 units. In Marine waters addition, waste discharges shall not cause the natural pH range to be excepting Bathing extended by more than 0.2 unit. Beach Subzones (b) Waste discharges shall not cause the pH of the water to exceed the Tuen Mun (A), range of 6.5-8.5 units. Tuen Mun (B) and Tuen Mun (C) Subzones and Water Gathering Ground Subzones (c) The pH of the water should be within the range of 6.0-9.0 units. Other inland waters (d) The pH of the water should be within the range of 6.0-9.0 units for Bathing Beach 95% of samples collected during the whole year. In addition, waste Subzones discharges shall not cause the natural pH range to be extended by more than 0.5 unit. F. TEMPERATURE Waste discharges shall not cause the natural daily temperature range to Whole zone change by more than 2.0 degrees Celsius. G. SALINITY Waste discharges shall not cause the natural ambient salinity level to Whole zone change by more than 10%. H. SUSPENDED SOLIDS (a) Waste discharges shall neither cause the natural ambient level to be Marine waters raised by more than 30% nor give rise to accumulation of suspended solids which may adversely affect aquatic communities. (b) Waste discharges shall not cause the annual median of suspended solids Tuen Mun (A), to exceed 20 mg per litre. Tuen Mun (B) and Tuen Mun (C) Subzones and Water Gathering Ground Subzones (c) Waste discharges shall not cause the annual median of suspended solids Other inland waters to exceed 25 mg per litre. I. AMMONIA The un-ionized ammoniacal nitrogen level should not be more than 0.021 mg Whole zone per litre, calculated as the annual average (arithmetic mean). J. NUTRIENTS (a) Nutrients shall not be present in quantities sufficient to cause Marine waters excessive or nuisance growth of algae or other aquatic plants. (b) Without limiting the generality of objective (a) above, the level of Castle Peak Bay inorganic nitrogen should not exceed 0.3 mg per litre, expressed as annual Subzone water column average (arithmetic mean of at least 3 measurements at 1 m below surface, mid-depth and 1 m above seabed). (c) Without limiting the generality of objective (a) above, the level of Marine waters inorganic nitrogen should not exceed 0.5 mg per litre, expressed as annual excepting Castle water column average (arithmetic mean of at least 3 measurements at 1 m Peak Bay below surface, mid-depth and 1 m above seabed). Subzone K. 5-DAY BIOCHEMICAL OXYGEN DEMAND (a) Waste discharges shall not cause the 5-day biochemical oxygen Tuen Mun (A), demand to exceed 3 mg per litre. Tuen Mun (B) and Tuen Mun (C) Subzones and Water Gathering Ground Subzones (b) Waste discharges shall not cause the 5-day biochemical Other inland waters oxygen demand to exceed 5 mg per litre. L. CHEMICAL OXYGEN DEMAND (a) Waste discharges shall not cause the chemical oxygen Tuen Mun (A), demand to exceed 15 mg per litre. Tuen Mun (B) and Tuen Mun (C) Subzones and Water Gathering Ground Subzones (b) Waste discharges shall not cause the chemical oxygen demand to exceed Other inland 30 mg per litre. waters M. TOXINS (a) Waste discharges shall not cause the toxins in water to attain such Whole zone levels as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans, fish or any other aquatic organisms, with due regard to biologically cumulative effects in food chains and to toxicant interactions with each other. (b) Waste discharges shall not cause a risk to any beneficial use of the Whole zone aquatic environment. N. PHENOL Phenols shall not be present in such quantities as to produce a specific Bathing Beach odour, or in concentration greater than 0.05 mg per litre as C6H5OH. Subzones O. TURBIDITY Waste discharges shall not reduce light transmission substantially from Bathing Beach the normal level. Subzones (Enacted 1992)