State of the Bay Report 2011-Final.pdf - Anchor Environmental

State of Saldanha Bay & Langebaan Lagoon 2011
Water quality
and 2011). In order to prevent this pattern being repeated in future, data should be collected at all
twenty sites on a bi-monthly basis throughout the year.
The revised ranks of 20 sites around the Saldanha Bay area are presented in Table 4.7. Two
sites in Small Bay (Small Quay – Sea Harvest and Hoedjies Bay) were ranked as ‘Poor’ (a decrease in
water quality from ‘Good’ and ‘Fair’ respectively in 2010). The Beach at Caravan Park was ranked as
‘Fair’ in 2011, an improvement on the situation in the previous three years where it was classed as
‘Poor’. The remaining four sites for which there was sufficient data available (Pepper Bay- Small
quay; Beach at Bok River Mouth; Leentijiesklip and Langebaan Yacht Club), were ranked as
‘Excellent’. In 2011, there were 12 sites which did not have sufficient data to assign a compliance
ranking, with one site (Seafarm – TNPA) having no data whatsoever available for analysis.
Guidelines state that samples should be collected 15-30 cm below the surface. In order to
minimise contamination and reduce sediment content, samples should be collected on the seaward
side of a recently broken wave. Samples to be tested for E. coli counts should be analysed within 6-8
hours of collection, and those to be tested for intestinal Enterococci, within 24 hours. Analyses
should be completed by an accredited laboratory, preferably one with ISO 17025 accreditation.
It is recommended that samples are analysed for intestinal Enterococci preferably over E.
coli. Several studies have shown that thermotolerant coliforms and E.coli to be relatively poor
indicators of health risks in marine waters. These organisms are also less resilient than Enterococci
(and other pathogenic bacteria) so if analysis is focussed on coliforms, the risk could be
underestimated due to mortality occurring in the time taken between collection and analysis.
In addition to this, an operational management process was recommended for South Africa,
following Enterococci counts (Figure 4.8). A mode is assigned based on the levels of Enterococci in a
single count (Green or Amber) or on consecutive counts (Red). Each mode outlines a plan of action
to be undertaken to deal with the problem.
Figure 4.8.
An illustration of the proposed routine monitoring programme to be trialled in South Africa.
Source: South African Water Quality Guidelines for Coastal Marine Waters (RSADEA 2011).
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