Nine MSN
The potentially
fatal bugs that contaminated Sydney's water supply in 1998 have
been found in nearly every waterway entering the Sydney catchment,
a NSW government report has revealed.
The 1999-2000
Sydney Catchment Authority (SCA) report revealed cryptosporidium
and giardia had been found in Warragamba Dam and Prospect Reservoir.
But the SCA
said the levels had been so low as to not cause a health risk.
And monitoring
since the publication of the report had failed to find further
evidence of the bugs.
According
to the water quality monitoring report, cryptosporidium were found
at most of the waterways feeding into Lake Burragorang - the main
source of Sydney's drinking water.
At one of
the sample sites, cryptosporidium levels had reached 23,400 occysts
- tiny cysts of the organism - about 20 times higher than the
levels that had forced water supplies to be cut off in 1998.
The report
linked nearby sewage treatment plants, farms and unsewered townships
to the contamination.
A special
investigation found cryptosporidium occysts had been detected
"in at least one sample from each Lake Burragorang inflow
site" except the Cox and Nattai rivers.
Of 58 samples
collected from Werribee Creek, four were contaminated with cryptosporidium.
"The
densities were relatively high," the report said.
"The
sampling site at Werribee Creek is located downstream of a number
of unsewered townships and farming land."
But an SCA
spokeswoman said the highest readings of the bugs had occurred
near a sewage treatment plant that had since been shut down.
She urged
people not to panic as readings taken since the report had given
Sydney's water supply the all-clear.
"The
SCA undertakes regular water quality tests and our readings show
there is no cryptosporidium or giardia in Sydney's water supply
at all," the spokeswoman told AAP.
"The
report was from tests taken more than a year ago and the high
readings were recorded at a site near a sewage treatment plant
which has since been decommissioned.
"The
higher readings at the time had no impact on Sydney's drinking
water as they were in the catchment, not in the actual water supply,"
she said.
"We would
really want to reassure people that the water supply is safe to
drink."
The bugs are
found in the guts of most warm-blooded animals but only have a
limited survival rate.
Sewage washing
into catchments during wet weather is often the key source of
contamination.
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