| (Cap 358 section 5) [7 October 1994] (L.N. 521 of 1994) Cap 358AO s 1 The water quality objectives set out in column 1 of the Schedule are established for those parts of the Victoria Harbour (Phase One) Water Control Zone set opposite those water quality objectives in column 2. (Enacted 1994) Cap 358AO SCHEDULE [section 1] Water Quality Objective Part or Parts of Zone A. AESTHETIC APPEARANCE (a) There should be no objectionable odours or discolouration of the water. (b) Tarry residues, floating wood, articles made of glass, plastic, rubber or of any other substances should be absent. (c) Mineral oil should not be visible on the surface. Surfactants should not give rise to a lasting foam. (d) There should be no recognisable sewage-derived debris. (e) Floating, submerged and semi-submerged objects of a size likely to interfere with the free movement of vessels, or cause damage to vessels, should be absent. (f) The water should not contain substances which settle to form objectionable deposits. Whole zone Whole zone Whole zone Whole zone Whole zone Whole zone B. BACTERIA The level of Escherichia coli should not exceed 1000 per 100 mL, calculated as the geometric mean of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days. Inland waters C. COLOUR Inland waters Human activity should not cause the colour of water to exceed 50 Hazen units. D. DISSOLVED OXYGEN (a) The level of dissolved oxygen should not fall below 4 mg per litre for 90% of the sampling occasions during the whole year; values should be calculated as the annual water column average (see Note). 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) The level of dissolved oxygen should not be less than 4 mg per litre. Marine waters Inland waters E. pH (a) The pH of the water should be within the range of 6.5-8.5 units. In addition, human activity should not cause the natural pH range to be extended by more than 0.2 unit. (b) Human activity should not cause the pH of the water to exceed the range of 6.0-9.0 units. Marine waters Inland waters F. TEMPERATURE Human activity should not cause the daily temperature range to change by more than 2.0 degrees Celsius. Whole zone G. SALINITY Human activity should not cause the salinity level to change by more than 10%. Whole zone H. SUSPENDED SOLIDS (a) Human activity should neither cause the suspended solids concentration to be raised more than 30% nor give rise to accumulation of suspended solids which may adversely affect aquatic communities. (b) Human activity should not cause the annual median of suspended solids to exceed 25 mg per litre. Marine waters Inland waters I. AMMONIA The un-ionized ammoniacal nitrogen level should not be more than 0.021 mg per litre, calculated as the annual average (arithmetic mean). Whole zone J. NUTRIENTS (a) Nutrients should not be present in quantities sufficient to cause excessive or nuisance growth of algae or other aquatic plants. (b) Without limiting the generality of objective (a) above, the level of inorganic nitrogen should not exceed 0.4 mg per litre, expressed as annual water column average (see Note). Marine waters Marine waters K. 5-DAY BIOCHEMICAL OXYGEN DEMAND The 5-day biochemical oxygen demand should not exceed 5 mg per litre. Inland waters L. CHEMICAL OXYGEN DEMAND The chemical oxygen demand should not exceed 30 mg per litre. Inland waters M. TOXIC SUBSTANCES (a) Toxic substances in the water should not attain such 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 interactions of toxic substances with each other. (b) Human activity should not cause a risk to any beneficial use of the aquatic environment. Whole zone Whole zone Note: Expressed normally as the arithmetic mean of at least 3 measurements at 1 m below surface, mid depth and 1 m above the seabed. However in water of a depth of 5 m or less the mean shall be that of 2 measurements (1 m below surface and 1 m above seabed), and in water of less than 3 m the 1 m below surface sample only shall apply. (Enacted 1994) |
