Hong Kong Regulations

STATEMENT OF WATER QUALITY OBJECTIVES (MIRS BAY WATER CONTROL ZONE) - SCHEDULE SCHEDULE

[paragraph 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 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)  Waste discharges shall not cause the water to 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 100mL,
        calculated as the geometric mean of all samples collected in one
        calendar year.

   (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.

   (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 Subzones and Fish Culture Subzones (L.N. 456 of
1991)
Water Gathering Ground Subzones

Other inland waters of the Zone C. COLOUR

   (a)  Waste discharges shall not cause the colour of water to exceed 30
        Hazen units.

   (b)  Waste discharges shall not cause the colour of water to exceed 50
        Hazen units.
Water Gathering Ground Subzones
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.

   (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.

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

Fish Culture 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
        addition, waste discharges shall not cause the natural pH range to be
        extended by more than 0.2 units.

   (b)  Waste discharges shall not cause the pH of the water to exceed the
        range of 6.5-8.5 units.

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

Water Gathering Ground Subzones
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.

   (b)  Waste discharges shall not cause the annual median of suspended solids
        to exceed 20 milligrams per litre. Marine waters

Water Gathering Ground Subzones and Other inland waters of the Zone

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.

   (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).
Marine waters K. 5-DAY BIOCHEMICAL OXYGEN DEMAND

   (a)  Waste discharges shall not cause the 5-day biochemical oxygen demand
        to exceed 3 milligrams per litre.

   (b)  Waste discharges shall not cause the 5-day biochemical oxygen demand
        to exceed 5 milligrams per litre.
Water Gathering Ground Subzones

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.

   (b)  Waste discharges shall not cause the chemical oxygen demand to exceed
        30 milligrams per litre. Water Gathering Ground Subzones
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.

   (b)  Waste discharges shall not cause a risk to Whole Zone any beneficial
        uses of the aquatic environment. Whole Zone
Whole Zone (Enacted 1990)