Health Warning Lifted For Algal Bloom In The Ashley/Rakahuri River At Gorge Bridge

Recent cyanobacteria surveys of the Ashley/Rakahuri River
at Gorge Bridge has shown the cover of potentially toxic
algae (benthic cyanobacteria) in the river has reduced and
is now below levels that are of concern to public
health.

Dr Cheryl Brunton, Medical Officer of Health
for the National Public Health Service, says Environment
Canterbury’s monitoring of Ashley/Rakahuri River at Gorge
Bridge will continue to the end of this summer and then will
resume next summer when there is increased likelihood of
cyanobacteria growth.

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 Te Mana Ora | Community and Public Health 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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