JUNK BAY WATER CONTROL ZONE STATEMENT OF WATER QUALITY OBJECTIVES

JUNK BAY WATER CONTROL ZONE STATEMENT OF WATER QUALITY OBJECTIVES

JUNK CONTROL ZONE STATEMENT OF WATER
OBJECTIVES
(Cap 358, section 5)
[28 July 1989]

L.N. 248 of 1989
1. Citation

The water quality objectives set out in the first column of Schedule 1 have
been established for those parts of the Junk Bay Water Control Zone defined in
Schedule 2 set opposite those water quality objectives in the second column of
Schedule 1.

SCHEDULE 1

Water Quality Objective Part or parts of Zone

A. AESTHETIC APPEARANCE

(a) Waste discharges shall cause no objectionable odours Whole Zone
or discolouration ofthe water.
(b) Tarry residues, floating wood, articles made of glass, Whole Zone
plastic, rubber or of any other substance should be
absent.
(c) Mineral oil should not be visible on the surface. Whole Zone
Surfactants should not give rise to a lasting foam.
(d) There should be no recognizable sewage-derived Whole Zone
debris.
(e) Floating, submerged and semi-submerged objects of a Whole Zone
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 Whole Zone
substances which settle to form objectionable
deposits.
B. BACTERIA
(a) Waste discharges shall not cause the level of Secondary Contact
Escherichia coli to exceed 1000 per 100 mI, in more Recreaton Subzone and
than 60% of the samples collected during the whole Fish Culture Subzones
year.
(b) The level of Escherichia coli should not exceed Bathing Beach Subzones
1000 per 100 mI, calculated as the running median of
the most recent 5 consecutive samples. Samples should
be taken 3 times in one calendar month at intervals of
between 3 and 14 days. The sampling programme
extends from March to October inclusive in any year.
(c) The level of Escherichia coli should not exceed 1000 Inland waters
per 100 mI, calculated as the running median of the
most recent 5 consecutive samples taken at intervals of
between 7 and 21 days.





Water Quality Objective Part or parts of Zone

C. COLOUR

Waste discharges shall not cause the colour of water to Inland waters
exceed 50 Hazen units.
D. DISSOLVED OXYGEN
(a) Waste discharges shall not cause the level of dissolved Marine waters excepting
oxygen to fall below 4 mg per litre for 90% of the Fish Culture Subzones
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 Fish Culture Subzones
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 Inland waters
oxygen to be less than 4 mg per litre.
E. pH
(a) The pH of the water should be within the range of Marine waters excepting
6.5-8.5 units. In addition, waste discharges shall not Bathing Beach Subzones
cause the natural pH range to be extended by more
than 0.2 units.
(b) The pH of the water should be within the range of Bathing Beach Subzones
6.0-9.0 units for 95% of samples. In addition, waste
discharges shall not cause the natural pH range to be
extended by more than 0.5 units.
(c) The pH of the water should be within the range of Inland waters
6.(~--9.0 units.
F. TEMPERATURE
Waste discharges shall not cause the natural daily Whole Zone
temperature range to change by more than 2.0C.
G. SALINITY
Waste discharges shall not cause the natural ambient Whole Zone
salinity level to change by more than 10 %.
H. SUSPENDED SOLIDS
(a) Waste discharges shall neither cause the natural Marine waters
ambient level to be raised by 30% nor give rise to
accumulation of suspended solids which may
adversely affect aquatic communities.





Water Quality Objective Part or parts of Zone

(b) Waste discharges shall not cause the annual median of Inland waters
suspended solids to exceed 25 mg per litre.
AMMONIA
The ammonia nitrogen level should not be more than 0.021 Whole Zone
mg per litre, calculated as the annual average (arithmetic
mean), as unionized form.

J. NUTRIENTS
(a) Nutrients shall not be present in quantities sufficient Marine waters
to cause excessive or nuisance growth of algae or other
aquatic plants.
(b) Without limiting the generality of objective (a) above, Marine waters
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).
K. 5-DAY BIOCHEMICAL OXYGEN DEMAND
Waste discharges shall not cause the 5-day biochemical Inland waters
oxygen demand to exceed 5 mg per litre.
L. CHEMICAL OXYGEN DEMAND
Waste discharges shall not cause the chemical oxygen Inland waters
demand to exceed 30 mg per litre.
M. DANGEROUS SUBSTANCES
(a) Waste discharges shall not cause the concentrations of Whole Zone
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
toxicamt interactions with each other.
(b) Waste discharges of dangerous substances shall not Whole Zone
put a risk to any beneficial uses of the aquatic
environment.

N. PHENOL
Phenols shall not be present in such quantities as to Bathing Beach Subzones
produce a specific odour, or in concentrations greater than
0.05 mg per litre as C61-150H.

0. TURBIDITY
No changes in turbidity or other factors arising from waste Bathing Beach Subzones
discharges shall reduce light transmission substantially
from the normal level.





SCHEDULE 2

In this statement-

'bathing beach subzone' means a bathing beach that is specified in the Fourth Schedule to the
Public Health and Municipal Services Ordinance (Cap. 132) and is situated in the Junk Bay
Water Control Zone;

'fish culture subzone' means a fish culture zone that is designated in the Fish Culture Zone
(Designation) Order (Cap. 353 sub. leg.) and situated in the Junk Bay Water Control Zone;

'Map' means a 1:20 000 map marked JBWCZ signed by the Secretary for Lands and Works,

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