Health Warning Lifted For Algal Bloom In Pareora River/Pureora At Pareora Huts

Health New Zealand | Te Whatu Ora has lifted its algal
bloom health warning issued for the Pareora River/Pureora at
Pareora Huts. This was issued on 30 November
2023.

Recent cyanobacteria surveys of the Pareora
River/Pureora at Pareora Huts has shown the cover of toxic
algae (benthic cyanobacteria) in the river has reduced and
is now below levels that are of concern to public
health.

Dr Matthew Reid, Medical Officer of Health for
the National Public Health Service, says Environment
Canterbury’s monitoring of the Pareora River/Pureora will
continue to the end of this summer and then will resume next
summer when there is increased likelihood of cyanobacteria
growth.

The warnings listed below remain in place for
the following South Canterbury waterways due to ongoing
algal blooms:

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

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/

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