Hong Kong Regulations

JUNK BAY WATER CONTROL ZONE STATEMENT OF WATER QUALITY OBJECTIVES - SCHEDULE 1

Water Quality Objective
Part or parts of Zone A. AESTHETIC APPEARANCE

   (a)  Waste discharges shall cause no objectionable odours or discolouration
        of the water.

   (b)  Tarry residues, floating wood, articles made of glass, plastic, rubber
        or of any other substance 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 recognizable 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)  Waste discharges shall not cause the water to Whole Zone contain
        substances which settle to form objectionable deposits.
Whole Zone

Whole Zone

Whole Zone

Whole Zone
Whole Zone

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.

   (b)  (Repealed L.N. 451 of 1991)

   (c)  The level of Escherichia coli should not exceed 1000 per 100 ml,
        calculated as the running median of the most recent 5 consecutive
        samples taken at intervals of between 7 and 21 days.
Secondary Contact
Recreation Subzone and Fish Culture Subzones (L.N. 451 of 1991)

Inland waters C. COLOUR Waste discharges shall not cause the colour of water
to exceed 50 Hazen units.
Inland waters D. DISSOLVED OXYGEN

   (a)  Waste discharges shall not cause the level of dissolved oxygen to fall
        below 4 mg per litre for 90% of the sampling occasions during the
        year; values should be calculated as the 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 year.

   (b)  The dissolved oxygen level should not be less than 5 mg 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 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 year.

   (c)  Waste discharges shall not cause the level of dissolved oxygen to be
        less than 4 mg per litre.
Marine waters excepting Fish Culture Subzones

Fish Culture Subzones

Inland waters 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.

   (b)  (Repealed L.N. 451 of 1991)

   (c)  The pH of the water should be within the range of 6.0-9.0 units.
Marine waters (L.N. 451 of 1991)

Inland waters F. TEMPERATURE Waste discharges shall not cause the natural
daily temperature range to change by more than 2.0 degrees 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.

   (b)  Waste discharges shall not cause the annual median of suspended solids
        to exceed 25 mg per litre.
Marine waters

Inland waters I. AMMONIA The ammonia nitrogen level should not be more than
0.021 mg per litre, calculated as the annual average (arithmetic mean), as
unionized form.
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.

   (b)  Without limiting the generality of objective (a) above, the level of
        inorganic nitrogen should not exceed 0.3 mg per litre, expressed as
        annual water column average (arithmetic mean of at least 3
        measurements at 1 m below surface, mid-depth and 1 m above seabed).
Marine waters

Marine waters

K. 5-DAY BIOCHEMICAL OXYGEN DEMAND Waste discharges shall not cause the 5-day
biochemical oxygen demand to exceed 5 mg per litre.
Inland waters L. CHEMICAL OXYGEN DEMAND Waste discharges shall not cause the
chemical oxygen demand to exceed 30 mg per litre.
Inland waters M. DANGEROUS SUBSTANCES

   (a)  Waste discharges shall not cause the concentrations of dangerous
        substances in the water to attain such levels as to produce
        significant toxic 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 of dangerous substances shall not put a risk to any
        beneficial uses of the aquatic environment.
Whole Zone

Whole Zone N-O. (Repealed L.N. 451 of 1991) (Enacted 1989)