Health Warning – Algal Bloom In The South Bank Tributary Of The Waiau/Uwha River Above The Waiau Bridge

Te Whatu Ora has issued a health warning for the South
Bank Tributary of the Waiau /Uwha River above the Waiau
Bridge.

The warning follows finding moderate to high
cover of potentially toxic algae (benthic cyanobacteria) in
a tributary of the Waiau/Uwha River.

People should
avoid the area and animals, particularly dogs, should not be
allowed near the water until the health warning has been
lifted.

There are also other access points along the
Waiau/Uwha River that may have benthic cyanobacteria
present. People are advised to treat every low-flowing river
cautiously, check for the presence of benthic cyanobacteria
and avoid contact.

Dr Matt Reid, Canterbury Medical
Officer of Health, National Public Health Service, says the
algae look like dark brown to black mats and can produce
toxins harmful to people and animals.

“Exposure may
cause skin rashes, nausea, stomach cramps, tingling and
numbness around the mouth and fingertips.”

“If you
experience any of these symptoms, visit your doctor
immediately, also let your doctor know if you’ve had
contact with dark brown/black algal mats or water in this
area,” Dr Matt Reid says.

Pets that show signs of
illness after coming into contact with algal mats should be
taken to a vet immediately.

People and animals should
remain out of the waterways until the warnings have been
lifted.

Environment Canterbury is monitoring the sites
and the public will be advised of any changes in water
quality.

Facts about cyanobacteria:

· Appears
as dark brown/black mats attached to rocks along the
riverbed.

· A low cover of the algae can occur
naturally but can increase rapidly during warmer months.
Algal blooms are influenced by a combination of available
nutrients in the water and sediments (such as nitrogen and
phosphorus), a sustained period of low and stable flows, and
favourable weather conditions (e.g. increased temperature,
calm days).

· It often has a strong musty smell and
algal toxin concentrations can vary over short
periods.

· Although high river levels will remove the
algal bloom, detached mats can accumulate along the shore
and increase the risk of exposure to toxins.

· If a
health warning is in place avoid contact with the
water.

· Although district or city councils may place
warning signs, these may not be seen at the numerous river
access points, hence the need for people/ dog-walkers to
treat every low-flowing river cautiously.

For further
details visit: https://www.lawa.org.nz/explore-data/canterbury-region/

Or
contact the Canterbury Public Health team on (03) 364
1777:

https://www.cph.co.nz/your-health/recreational-water/

For
more information about Mahinga Kai:

https://www.cph.co.nz/wp-content/uploads/saf0112.pdf

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