Hong Kong Regulations

TOLO HARBOUR AND CHANNEL WATER CONTROL ZONE STATEMENT OF WATER QUALITY OBJECTIVES FOR WATERCOURSES - SCHEDULE 1

Water Quality Objective for Watercourses
Subzone A. AESTHETIC APPEARANCE Waste discharges shall not cause waters of the
subzone to contain substances that-

   (a)  settle to form objectionable deposits;

   (b)  float as debris, scum, oil or other matter to form nuisances;

   (c)  produce objectionable colour, odour, taste or turbidity;

   (d)  injure or are toxic or produce adverse physiological responses in
        humans, animals or plants; or

   (e)  are conducive to undesirable aquatic life or a nuisance to aquatic
        life.
All watercourses B. BACTERIA Waste discharges shall not cause the level of
Escherichia coli to exceed 1000 per 100 ml in waters of the subzone, levels to
be calculated as a running median of the most recent 5 consecutive samples
taken at intervals of between 7 and 21 days (or 14 and 42 days). (a) SM(A)

   (b)  SM(C)

   (c)  SM(D)

   (d)  SM(E)

   (e)  SM(H)

   (f)  SM(I)

   (g)  TP(B)

   (h)  TP(C)

   (i)  other water-
courses

Waste discharges shall not cause the level of Escherichia coli to exceed 0 per
100 ml in waters of the subzone, levels to be calculated as a running median
of the most recent 5 consecutive samples taken at intervals of between 7 and
21 days (or 14 and 42 days). (a) SM(B)

   (b)  SM(F)

   (c)  SM(G)

   (d)  LT(C)

   (e)  LT(D)

   (f)  TP(A)

C. COLOUR Waste discharges shall not cause the colour of waters of the subzone
to exceed 50 Hazen units at any time. (a) SM(A)

   (b)  SM(C)

   (c)  SM(D)

   (d)  SM(E)

   (e)  SM(H)

   (f)  SM(I)

   (g)  TP(B)

   (h)  TP(C)

   (i)  other water-
courses

Waste discharges shall not cause the colour of waters of the subzone to exceed
30 Hazen units at any time. (a) SM(B)

   (b)  SM(F)

   (c)  SM(G)

   (d)  LT(C)

   (e)  LT(D)

   (f)  TP(A) D. pH Waste discharges shall not cause the pH of waters of the
        subzone to exceed the range of 6.0 to 9.0 at any time. (a) SM(D)

   (b)  SM(E)

   (c)  SM(I)

   (d)  other water-
courses

Waste discharges shall not cause the pH of waters of the subzone to exceed the
range of 6.5 to 8.5 at any time. (a) SM(A)

   (b)  SM(B)

   (c)  SM(C)

   (d)  SM(F)

   (e)  SM(G)

   (f)  SM(H)

   (g)  LT(C)

   (h)  LT(D)

   (i)  TP(A)

   (j)  TP(B)

   (k)  TP(C)

E. TEMPERATURE All watercourse Waste discharges shall not cause the natural
daily temperature range in waters of the subzone to be extended by greater
than +/- 2.0 degrees Celsius at any location or time.

F. SUSPENDED SOLIDS Waste discharges shall not cause the annual median of
suspended solids in waters of the subzone to exceed 25 milligrams per litre.
(a) SM(D)

   (b)  SM(E)

   (c)  SM(I)

   (d)  other water-
courses

Waste discharges shall not cause the annual median of suspended solids in
waters of the subzone to exceed 20 milligrams per litre. (a) SM(A)

   (b)  SM(B)

   (c)  SM(C)

   (d)  SM(F)

   (e)  SM(G)

   (f)  SM(H)

   (g)  LT(C)

   (h)  LT(D)

   (i)  TP(A)

   (j)  TP(B)

   (k)  TP(C)

G. DISSOLVED OXYGEN Waste discharges shall not cause the level of dissolved
oxygen in waters of the subzone to be less than 4 milligrams per litre or 40%
saturation

(at 15 degrees Celsius) at any time.
All watercourses H. 5 DAYS BIOCHEMICAL OXYGEN DEMAND Waste discharges shall
not cause the 5 days biochemical oxygen demand in waters of the subzone to
exceed 5 milligrams per litre at any time. (a) SM(A)

   (b)  SM(C)

   (c)  SM(D)

   (d)  SM(E)

   (e)  SM(H)

   (f)  SM(I)

   (g)  TP(B)

   (h)  TP(C)

   (i)  other water-
courses

Waste discharges shall not cause the 5 days biochemical oxygen demand in
waters of the subzone to exceed 3 milligrams per litre at any time (a) SM(B)

   (b)  SM(F)

   (c)  SM(G)

   (d)  LT(C)

   (e)  LT(D)

   (f)  TP(A)

I. CHEMICAL OXYGEN DEMAND Waste discharges shall not cause the chemical oxygen
demand in waters of the subzone to exceed 30 milligrams per litre at any time.
(a) SM(A)

   (b)  SM(C)

   (c)  SM(D)

   (d)  SM(E)

   (e)  SM(H)

   (f)  SM(I)

   (g)  TP(B)

   (h)  TP(C)

   (i)  other water-
courses

Waste discharges shall not cause the chemical oxygen demand in waters of the
subzone to exceed 15 milligrams per litre at any time. (a) SM(B)

   (b)  SM(F)

   (c)  SM(G)

   (d)  LT(C)

   (e)  LT(D)

   (f)  TP(A)

J. AMMONIACAL NITROGEN Waste discharges shall not cause the ammoniacal
nitrogen in waters of the subzone to exceed 0.5 milligrams per litre at any
time.
All watercourses K. TOXICANTS All watercourses Waste discharges shall not
cause the toxicants in waters of the subzone to attain such a level as to
produce significant toxic effects in humans, fish or any other aquatic
organism, with due regard to biologically cumulative effects in food chains
and to toxicant inter-actions with each other. (Enacted 1988)