Health Warning – Algal Bloom in the Waikirikiri-Selwyn River at Whitecliffs Domain

Te Mana Ora | Community and Public Health has issued a
health warning for the Waikirikiri-Selwyn River at
Whitecliffs Domain.

The warning follows finding
moderate to high cover of potentially toxic algae (benthic
cyanobacteria) in the Waikirikiri-Selwyn 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 Waikirikiri-Selwyn 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 Cheryl
Brunton, Medical Officer of Health for Te Mana Ora, 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 Brunton
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/

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