Alexandra doctor Dave Fearnley believes the public should
be warned about the high faecal bacterial levels at popular
swimming spots in the Manuherikia River near Alexandra,
such as under Shaky Bridge. Photo by Lynda Van Kempen.
Cooling off on a hot summer day with a dip in the
Manuherikia River near Alexandra might make you ill, an
Alexandra doctor says.
Dr Dave Fearnley is concerned about the ''dubious'' water
quality in the lower Manuherikia and its potential effect on
swimmers. Last summer, the Otago Regional Council's sampling
showed faecal bacteria (Escherichia coli) levels reached an
''action/red'' status near Alexandra four times, which meant
it could be a health risk for swimmers.
''Last summer, my nephew became unwell after swimming by the
Shaky Bridge. How many people might have their holidays
affected in a similar fashion this summer?'' Dr Fearnley
''During the recent warm weather there's been 20, 30 or up to
50 people swimming in the Manuherikia River under the bridge,
including lots of children. I wonder how many people get ill
after swimming here in summer and put it down to something
they've eaten, but it hasn't been food poisoning -it's been
The regional council website has a section called ''Water
Monitoring for Recreational Activities'' which outlines the
results from bacteria count sampling.
The samples are taken weekly from the most popular swimming
spots in Otago, from December through to the end of March.
The results are compared to national guidelines set by the
Ministry for the Environment and Ministry of Health and are
classified in three categories - green (should be very safe
for swimming), alert/amber (should be satisfactory for
swimming) and action/red (could be a health risk for
Regional council director of environmental information and
science John Threlfall said he would ''think twice'' about
swimming in the Manuherikia near Alexandra in summer.
''If I was looking at that spot, I'd swim there with caution
and in fact, I'd probably keep kids out of the water.
''But no waterway is 100% safe in terms of bacteria.''
He was surprised to find the bacteria level had reached
''action/red'' status four times last summer. Three were
''just over the line'' into a higher concentration of E. coli
while the fourth was high.
It was very difficult to isolate the causes of the high
bacteria count during low river flow.
''It could be farming practices, septic tanks, dead stock,
ducks upstream - wild fowl can make people sick - and another
source of bacteria during low flow is irrigation bywash,
especially flood irrigation, which is common upstream,'' Dr
The council was working towards cleaning up contamination
from farm and septic tank discharges but would consider more
intensive sampling upstream in the Manuherikia to check if
there was a pattern and if the source could be isolated.
Results from sampling took four to five days to come through,
he said. The most recent one showed the E. coli levels were
at ''alert/amber'' status, but Dr Threlfall believed the
results from last summer should be seen as an indicator of
what might happen this summer.
He would discuss the matter with the Central Otago District
Council and Public Health South. Dr Fearnley believed the
council had a responsibility to warn people their health
might be affected by swimming in the river.
''I wouldn't go so far as to say the ORC are negligent but I
believe if it's at a level that's unacceptable for human
health, they have a responsibility to advise the public,
rather than relying on them to read it online.''
The logical answer was to improve water quality, but
obviously that would not happen overnight, Dr Fearnley said.
''If people who become unwell after swimming were to report
their illness to the ORC, the health impact of poor water
quality might become better appreciated.''