COASTAL
WATER
QUALITY
2004
Status
Report
Introduction:
Water Quality Criteria, used to determine fitness for use and the protection of the natural aquatic
environment, include the physical, chemical, biological and aesthetic properties of the water. In
order to assess the sea water quality for bathing purposes, the City monitors bacterial indicators of
faecal pollution in the surf zone of bathing areas.
Results for the past twelve months have been evaluated against the South African Water Quality
Guidelines for Coastal Marine Waters (DWAF 1995 Volume 2: Recreational Use)
The guidelines specify desired values for the indicator organism, faecal coliforms, and are
summarised as follows:
* 80% of samples must contain not more than 100 faecal coliforms / E coli per 100ml
(80% limit and,
* 95% of samples must contain not more than 2000 faecal coliforms/ E coli per 100ml
(95% limit)
The location of monitoring points are shown below:
Sampling Points
Results : False Bay
This Year
Exceeds
Limit
SUMMER
(Oct 2003 - March 2004)
ALL YEAR
(Oct 2003 - Sept 2004)
ALL YEAR
(Oct 2003 - Sept 2004)
80th percentile
80th percentile
95th percentile
Millers Point
Fishermans Beach
Boulders Beach
Seaforth Beach
Long Beach
Glencairn Beach
Fish Hoek Beach
Silvermine River Mouth
Kalk Bay Harbour Beach
Kalk Bay
Kalk Bay Pool
Dalebrook Pool
St James Pool
Sandown Hotel
Muizenberg Station
Muizenberg Pavillion
Sunrise Beach
Lifebox 21
Lifebox 23
Sonwabe
Ribbon Parking Area
Lifebox 30
Strandfontein Point
Strandfontein Pool
Lukannon Drive WWPS
Mnandi Beach West
Mnandi Beach East
Monwabisi Tidal Pool
Monwabisi Beach
Macassar Beach
Strand-Lourens River Mouth
Strand - Woltemade St
Strand - Springbok Café
Strand - Pier
Strand - Harmony Resort
Gordons Bay - near River
G’Bay - van Riebeek Hotel
Gordons Bay - Harbour
G’Bay Bikini Beach
Kogel Bay Beach
1
10
100
1000
10 000
1
10
E coli/100ml
100
1000
10 000
1
10
E coli/100ml
100
1000
10 000
E coli/100ml
Previous Years
FULL YEAR
Year
Percentage
compliance for
bathing areas
1993
1994
1995
1996
1997
1998
1999
2000
2001
200
2
200
3
200
4
80 Percentiles
76
97
86
68
78
84
92
85
93
85
98
93
95 Percentiles
95
97
97
89
97
95
95
87
100
93
100
100
Number of Areas
37
37
37
37
37
37
38
39
40
40
40
40
See Annexure A for numerical results at each sample point.
Results : Table Bay
This Year
Exceeds
Limit
SUMMER
ALL YEAR
ALL YEAR
80th percentile
80th percentile
95th percentile
Silverstroom Tidal Pool
Melkbosstrand
Blouberg Small Bay
Tableview
Milnerton Beach
Granger Bay
Mouille Point Beach
Three Anchor Bay
Rocklands Beach
Graaff’s Pool
Milton Pool - inside
Sunset Beach Pool - outside
Saunders Rocks Pool - in
Saunders Rocks Beach
Clifton: 4th Beach
Clifton: Maiden’s Cove
Maiden’s Cove Pool I - in
Maiden’s Cove Pool II - in
Camps Bay Beach
Camps Bay Pool - nr W Wall
Horne Bay
Bakoven Bungalow
Oudekraal Resort
Llandudno Beach
Hout Bay Beach, East
Kommetjie, Long Beach
Kommetjie, The Kom
Scarborough Beach
1
10
100
1000
10 000
1
10
E coli/100ml
100
1000
10 000
1
10
E coli/100ml
Previous Years
100
1000
10 000
E coli/100ml
FULL YEAR
Year
Percentage
compliance for
bathing areas
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
80 Percentiles
80
100
81
73
85
70
70
82
75
68
89
82
95 Percentiles
92
100
85
100
92
96
89
86
86
86
93
96
Number of Areas
25
25
26
26
26
27
27
28
28
28
28
28
See Annexure B for numerical results at each sample point.
How Does Our Water Quality Compare?
Each year the European Union publishes a summary of bathing water quality on the
coastlines of their member countries. Because their criteria are very similar to those
used in the South African guidelines, we can easily compare their values with those
for False Bay and the Atlantic coast.
They use two criteria, a stringent Guideline to be aimed at and a less stringent
Mandatory Value, which is supposed to be complied with by all. These correspond
th
th
to the South African 80 and 95 percentile guidelines.
th
In Figure 4 the first bar graph indicates percentage compliance with the 80
th
percentile Guideline and the 95 percentile Mandatory Value, the second graph
th
indicates compliance with the 95 percentile Mandatory Value.
It should be noted that the figure indicates percentage compliance rather than level
of pollution. Higher values therefore represent less pollution. The European
statistics are for the 2003 calendar year.
As can be seen from these graphs Cape Town beaches compare favourably with
European beaches.
Guidline & Mandatory Value
80th & 95th Percentile
(Most Stringent)
Mandatory Value
95th Percentile
(Less Stringent)
United Kingdom
Sweden
Spain
Portugal
Netherlands
Italy
Ireland
Greece
Germany
Finland
Denmark
Belgium
False Bay
Table Bay
0
20
40
60
80
100
Percentage Beaches Complying
0
20
40
60
80
100
Percentage Beaches Complying
Brown water in False Bay
The most popular misconception is that the brown water phenomenon is caused by raw
sewage discharged into the sea. Ironically sewage is not brown, it rather resembles the
grey colour of waste water from a washing machine. Extensive studies of the patches has
however established that the discolouration is caused by the aggregation of tens of
thousands and sometimes millions of single celled plants known at diatoms. The
organism has been identified as Anaulus australis. It is unicellular and occurs naturally in
the surf zone along sandy beaches.
Anaulus australis has been monitored
by the City of Cape Town since 1989
on a fortnightly basis along the False
Bay coast between St James Tidal
Pool and Mnandi Beach East. There
are a total of twelve sample points on
which anaulus counts are done. The
highest concentrations are found in the
Are A between Sunrise Beach and
Lifebox 30. Trends based on the median
values of all the sa mple points indicate
a rise in the number of cells counted this
past year.
As can be seen in the graph there has
been no great variation in the numbers
over the past fifteen years.
Anaulus australis is not a pathogenic
organism and does not pose a health
risk to bathers despite the obvious
aesthetic aspect of swimming in
“dirty” brown water. Apart from the
Western and Eastern Cape, sightings
have been reported worldwide,
including the Mediterranean Sea,
California, North Islands of New
Zealand and the Hawaiian
Islands (CSIR, 1989).
Brown water along False Bay coast
Physical and chemical factors,
which control surf diatom blooms,
have been identified as nutrients,
Silicon (obtained from freshwater
Input from adjacent dunefields),
currents, temperature and wind.
The only way to limit the occurrence of brown water patches would involve an attempt at
modification of these factors. Research has confirmed that treated sewage effluent discharges
into False Bay are not a requirement for the formation of anaulus patches.
Annexure A
FALSE BAY - BACTERIOLOGICAL DATA
ALL YEAR
Oct 2003 - Sep 2004
Samples
E coli/100ml
Examined
Percentiles*
80% 95%
BATHING AREAS
Millers Point
Fishermans Beach
Boulders Beach
Seaforth Beach
Long Beach
Glencairn Beach
Fish Hoek Beach
Silvermine River Mouth
Kalk Bay Harbour Beach
Kalk Bay
Kalk Bay Pool
Dalebrook Pool
St James Pool
Sandown Hotel
Muizenberg Station
Muizenberg Pavilion
Sunrise Beach
Lifebox 21
Lifebox 23
Sonwabe
Ribbon Parking Area
Lifebox 30
Strandfontein Point
Strandfontein Tidal Pool
Lukannon Drive Pump Station
Mnandi Beach West
Mnandi Beach East
Monwabisi Tidal Pool
Mowabisi Beach
Macassar Beach
Strand Lourens River Mouth
Strand - Melkbaai - Woltemade St
Strand - Melkbaai - Springbok Café
Strand - Pier
Strand - Harmony Resort
Gordons Bay - nr Sir Lowry=s Pass River
Gordons Bay - van Riebeek Hotel
Gordons Bay - Harbour
Gordons Bay - Bikini Beach
Kogel Bay Beach
25
25
25
25
25
25
25
25
25
25
25
23
25
25
24
25
25
25
24
24
25
25
25
21
24
25
24
16
17
24
24
24
24
24
24
22
22
22
22
22
5
16
18
31
14
28
300+
23
21
14
18
16
16
244+
100
82
98
87
55
99
84
50
28
13
24
36
21
33
504+
44
28
17
24
30
27
12
12
11
10
14
53
68
232
186
135
137
1360
66
58
48
100
55
39
822
269
963
830
378
327
1820
372
310
52
67
108
105
100
^
^
478
189
193
136
174
144
194
451
98
72
68
SUMMER
Oct 2003 - Mar 2004
Samples
E coli/100ml
Examined
Percentile*
80%
13
13
13
13
13
13
13
13
13
13
13
11
13
13
13
13
13
13
13
13
13
13
13
10
13
13
13
8
8
13
13
13
13
13
13
11
11
11
11
11
* Values below which given percentage of results lie
+ Exceeds WQG 80% limit (80% of values not more than 100)
# Exceeds WQG 95% limit (95% of values not more than 2000)
3
15
16
12
20
30
597+
22
10
11
13
14
18
530+
95
48
17
84
42
13
11
17
7
9
12
44
44
63
56
21
15
6
6
10
8
19
7
6
12
10
Annexure B
ATLANTIC COAST - BACTERIOLOGICAL DATA
ALL YEAR
Oct 2003 - Sep 2004
Samples E coli/100ml
Examined
Percentiles*
80% 95%
BATHING AREAS
Silverstroom Tidal Pool
Melkbosstrand
Blouberg Small Bay
Table View
Milnerton Beach at Lighthouse
Granger Bay
Mouille Point Beach
Green Point Wastewater Outfall
Green Point opp. Park Road
Three Anchor Bay
Rocklands opp. Shoreham Flats
Rocklands Beach
Graaff's Pool
Milton Pool - inside
Milton Pool - outside
Sunset Beach Pool - outside
Saunders Rocks Pool - inside
Saunders Rocks Pool - outside
Saunders Rocks Beach
Clifton - 4th Beach
Clifton - Maidens Cove
Maidens Cove Tidal Pool I - inside
Maidens Cove Tidal Pool I - outside
Maidens Cove Tidal Pool II - inside
Maidens Cove Tidal Pool II - outside
Camps Bay Beach
Camps Bay Pool - inside near W wall
Camps Bay Pool - inside near toilet
Camps Bay Pool - outside
Horne Bay
Bakoven Bungalows
Oudekraal Resort
Llandudno Beach
Hout Bay Beach East
Kommetjie, Long Beach
Kommetjie, The Kom
Scarbrough Beach
*
+
#
^
23
23
23
23
23
23
24
21
24
24
24
24
24
20
23
23
23
7
24
23
22
20
21
19
20
24
20
20
23
24
24
25
25
25
25
25
25
25
27
25
24
26
49
48
25
132+
832+
123+
115+
183+
128+
338+
62
84
359+
426+
31
14
16
25
13
26
39
26
36
14
6
9
17
7
70
31
59
30
241
58
96
68
356
522
454
1640
706
5450#
1460
1830
1570
704
1440
424
582
^
971
89
58
140
96
142
71
119
54
321
39
33
49
94
82
323
102
120
108
SUMMER
Oct 2003 - Mar 2004
Samples E coli/100ml
Examined
Percentile*
80%
11
11
11
11
11
11
12
12
12
12
12
12
12
11
11
11
11
3
12
12
12
11
11
9
10
12
9
9
11
12
12
13
13
13
13
13
13
Values below which given percentage of results lie
Exceeds WQG 80% limit (80% of values not more than 100)
Exceeds WQG 95% limit (95% of values not more than 2000)
Insufficient data to accurately calculate this value
20
20
20
17
32
103+
51
14
53
254+
84
150+
162+
150+
153+
38
15
^
87
52
12
14
11
7
26
10
5
6
8
6
4
9
6
6
25
50
59