Opihi River Catchment Health Warning

Health New Zealand | Te Whatu Ora has issued a health
warning for the entire Opihi River Catchment.

The
warning follows finding moderate to high cover of toxic
algae (benthic cyanobacteria) at multiple sites across the
entire Opihi River Catchment.

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

All access points along the entire Opihi River
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 Matthew Reid, Medical Officer of Health
for the National Public Health Service, says the algae looks
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 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.

Sites that are currently under a temporary
health warning in South Canterbury
include:

• Pareora River/Pureora at SH1
  Bridge
• Hae Hae Te Moana River at
  Gorge
• Waihao River at Bradshaws Bridge
• Opihi
  River at SH79 Bridge
• Opihi River at
  SH1
• Opihi River at Grassy Banks
• Opihi River
  at Saleyards Bridge
• Opihi River at Raincliff
  Bridge
• Temuka River at Manse Bridge
• Temuka
  River at SH1 Bridge
• Saltwater Creek/Otipua at SH1
  Bridge.

Facts about benthic
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 Te Mana Ora | Community and Public Health on (03)
364 1777 or visit https://www.cph.co.nz/your-health/recreational-water/

For
more information about Mahinga Kai visit https://www.cph.co.nz/wp-content/uploads/saf0112.pdf

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