Cap. 358U 《水質指標聲明(大鵬灣水質管制區)》Statement of Water Quality Objectives (Mirs Bay Water Control Zone)

生效中

版本日期: 2023-12-13

Cap. 358T

Cap. 358V

Statement of Water Quality Objectives (Mirs Bay Water Control Zone)

(Cap. 358, section 5)

(Enacting provision omitted—E.R. 6 of 2019)

[30 November 1990]

(Format changes—E.R. 6 of 2019)

1.

The water quality objectives set out in column 1 of the Schedule are established for those parts of the Mirs Bay Water Control Zone set opposite those water quality objectives in column 2.

(E.R. 6 of 2019)

2.

In this Statement— (E.R. 6 of 2019)

Fish Culture Subzone (魚類養殖分區) means an area designated as a fish culture zone under the Fish Culture Zone (Designation) Order (Cap. 353 sub. leg. B) and situated in the Mirs Bay Water Control Zone; (L.N. 142 of 2023) marine waters (海洋水域) means all waters below the high water mark within the boundaries of the Mirs Bay Water Control Zone; Secondary Contact Recreation Subzone (次級接觸康樂活動分區) means an area delineated as such on the specified maps, except where the area is situated in a Fish Culture Subzone; (L.N. 142 of 2023) specified maps (指明地圖) means a series of maps marked MBWCZ 1A, MBWCZ 2A, MBWCZ 3A, MBWCZ 4A and MBWCZ 5A, signed by the Secretary for Environment and Ecology on 12 October 2023 and deposited in the Land Registry; (L.N. 142 of 2023) Water Gathering Ground Subzone (集水地區分區) means an area delineated as such on maps marked MBWCZ 1A and MBWCZ 3A among the specified maps. (L.N. 142 of 2023)

(L.N. 142 of 2023)

Schedule

[para. 1]


A.	AESTHETIC APPEARANCE
	(a)Waste discharges shall cause no objectionable odours or discolouration of the water.	Whole Zone
	(b)Tarry residues, floating wood, articles made of glass, plastic, rubber or of any other substances should be absent.	Whole Zone
	(c)Mineral oil should not be visible on the surface. Surfactants should not give rise to a lasting foam.	Whole Zone
	(d)There should be no recognisable sewage-derived debris.	Whole Zone
	(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.	Whole Zone
	(f)Waste discharges shall not cause the water to contain substances which settle to form objectionable deposits.	Whole Zone

B.	BACTERIA
	(a)The level of Escherichia coli should not exceed 610 per 100 mL, calculated as the geometric mean of all samples collected in one calendar year.	Secondary Contact Recreation Subzones and Fish Culture Subzones (L.N. 456 of 1991)
	(b)The level of Escherichia coli should be zero per 100 mL, calculated as the running median of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days.	Water Gathering Ground Subzones
	(c)The level of Escherichia coli should not exceed 1 000 per 100 mL, calculated as the running median of the most recent 5 consecutive samples taken at intervals of between 7 and 21 days.	Other inland waters of the Zone
		(E.R. 6 of 2019)

C.	COLOUR
	(a)Waste discharges shall not cause the colour of water to exceed 30 Hazen units.	Water Gathering Ground Subzones (E.R. 6 of 2019)
	(b)Waste discharges shall not cause the colour of water to exceed 50 Hazen units.	Other inland waters of the Zone

D.	DISSOLVED OXYGEN
	(a)Waste discharges shall not cause the level of dissolved oxygen to fall below 4 milligrams per litre for 90% of the sampling occasions during the year; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1 metre below surface, mid-depth and 1 metre above seabed). In addition, the concentration of dissolved oxygen should not be less than 2 milligrams per litre within 2 metres of the seabed for 90% of the sampling occasions during the year.	Marine waters excepting Fish Culture Subzones
	(b)The dissolved oxygen level should not be less than 5 milligrams per litre for 90% of the sampling occasions during the year; values should be calculated as water column average (arithmetic mean of at least 3 measurements at 1 metre below surface, mid-depth and 1 metre above seabed). In addition, the concentration of dissolved oxygen should not be less than 2 milligrams per litre within 2 metres of the seabed for 90% of the sampling occasions during the year.	Fish Culture Subzones
	(c)Waste discharges shall not cause the level of dissolved oxygen to be less than 4 milligrams per litre.	Water Gathering Ground Subzones and Other inland waters (E.R. 6 of 2019)

E.	pH
	(a)The pH of the water should be within the range of 6.5–8.5 units. In addition, waste discharges shall not cause the natural pH range to be extended by more than 0.2 units.	Marine waters
	(b)Waste discharges shall not cause the pH of the water to exceed the range of 6.5–8.5 units.	Water Gathering Ground Subzones (E.R. 6 of 2019)
	(c)The pH of the water should be within the range of 6.0–9.0 units.	Other inland waters of the Zone

F.	TEMPERATURE
	Waste discharges shall not cause the natural daily temperature range to change by more than 2.0 degree Celsius.	Whole Zone

G.	SALINITY
	Waste discharges shall not cause the natural ambient salinity level to change by more than 10%.	Whole Zone

H.	SUSPENDED SOLIDS
	(a)Waste discharges shall neither cause the natural ambient level to be raised by 30% nor give rise to accumulation of suspended solids which may adversely affect aquatic communities.	Marine waters
	(b)Waste discharges shall not cause the annual median of suspended solids to exceed 20 milligrams per litre.	Water Gathering Ground Subzones and Other inland waters of the Zone (E.R. 6 of 2019)

I.	AMMONIA
	The un-ionized ammoniacal nitrogen level should not be more than 0.021 milligram per litre, calculated as the annual average (arithmetic mean).	Whole Zone

J.	NUTRIENTS
	(a)Nutrients shall not be present in quantities sufficient to cause excessive or nuisance growth of algae or other aquatic plants.	Marine waters
	(b)Without limiting the generality of objective (a) above, the level of inorganic nitrogen should not exceed 0.3 milligram per litre, expressed as annual water column average (arithmetic mean of at least 3 measurements at 1 metre below surface, mid-depth and 1 metre above seabed).

K.	5-DAY BIOCHEMICAL OXYGEN DEMAND
	(a)Waste discharges shall not cause the 5-day biochemical oxygen demand to exceed 3 milligrams per litre.	Water Gathering Ground Subzones (E.R. 6 of 2019)
	(b)Waste discharges shall not cause the 5-day biochemical oxygen demand to exceed 5 milligrams per litre.	Other inland waters of the Zone

L.	CHEMICAL OXYGEN DEMAND
	(a)Waste discharges shall not cause the chemical oxygen demand to exceed 15 milligrams per litre.	Water Gathering Ground Subzones (E.R. 6 of 2019)
	(b)Waste discharges shall not cause the chemical oxygen demand to exceed 30 milligrams per litre.	Other inland waters of the Zone

M.	TOXINS
	(a)Waste discharges shall not cause the toxins in water to attain such levels as to produce significant toxic, carcinogenic, mutagenic or teratogenic effects in humans or fish or any other aquatic organisms, with due regard to biologically cumulative effects in food chains and to toxicant interactions with each other.	Whole Zone
	(b)Waste discharges shall not cause a risk to any beneficial uses of the aquatic environment.	Whole Zone