What do we sample for?
For swimmer health and safety we monitor faecal bacteria and
turbidity.
Microorganisms
Microorganisms, such as bacteria, protozoa and fungi, are present
everywhere in the environment, including in beach waters. Most
microorganisms are harmless and many are even beneficial. We monitor
a few specific bacteria to identify possible faecal pollution
from humans and animals. Faecal waste may contain bacteria and
other organisms that are harmful to bathers. Faecal waste pollution
can reach coastal water from treated sewage discharges, boats,
jetties and stormwater runoff from rivers and drains, or it may
come from bathers in the waters.
The key bacteria that are monitored are enterococci, which are
commonly found in the wastes of warm-blooded animals, including
birds, livestock, dogs, cats and humans.
There are established guideline values for enterococci, based
on criteria from the World Health Organization (WHO), that can
be used to determine whether bathing water is safe (see Water
Quality Classification Table below). These guidelines incorporate
local knowledge of potential sources of faecal waste in the coastal
waters and stormwater discharging into these waters.
Water clarity
Poor water clarity reduces visibility and may result in bathing
accidents. It can also make water look less appealing for swimming.
Water clarity can be reduced by dust and other matter from stormwater
runoff (mostly from soil and stream bank erosion), and industry
and sewage discharges. Water clarity is obtained by determining
the turbidity. >>
More
How we decide if the water quality is good?
We classify the water quality at each site as good, moderate
or poor. To decide which of these categories best describes the
water, we compare the water quality against international and
state guidelines. Classifications are shown below.
Water Quality Classification Table
|
Parameter
|
Good
|
Moderate
|
Poor
|
| Bacteria |
|
|
|
| Enterococci (organisms/100 mL) |
<200
|
200-500
|
>500
|
| Water clarity |
|
|
|
| Turbidity (NTU) |
<5
|
5-25
|
>25
|
The following resources were used to provide these guidelines:
The water quality indicators shown in the Water
Quality for Adelaide and Encounter Bay Beaches Map (274KB
PDF) show overall water quality. These indicators are based
on the worst result for the site. For example, if turbidity was
high enough to be considered 'poor', the classification would
be shown as poor, even if enterococci counts were considered good.
This page was last modified 08-01-2008
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