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Cyanobacteria warnings

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Recent Horizons Regional Council monitoring has found brown/black algal mats of cyanobacteria at a number of popular river swimming spots throughout the region.

These mats are exposed at the river's edge as water levels have dropped due to the current dry conditions.  High levels of cyanobacteria and/or exposed mats have been found at some spots on the Mangatainoka, Manawatu, Pohangina, Oroua and Ohau rivers at swim spots such as the Woodville Ferry Reserve and Totara Reserve.
Cyanobacteria can produce toxins harmful to humans if swallowed or when skin contact occurs.  In humans these toxins can cause vomiting, diarrhoea and skin irritations.
MidCentral DHB Medical Officer of Health, Dr Rob Weir, advises the public they need to heed any health warnings.  He said: “People can check if their favourite swimming spot has a cyanobacteria warning on the Land Air Water Aotearoa (LAWA) website ‘Can I swim here?’ section. Information signs have also been posted at key access points by Horizons Regional Council staff. These signs show pictures of cyanobacteria so river users know what to look for.
“Boiling water does not remove toxins produced by cyanobacteria.  Drinking water suspected to have cyanobacteria in it should be avoided at all times.”
For further information, visit or contact a Health Protection Officer at MidCentral Public Health Services on 06 350 9110.
Contact: Communications Unit (06) 350-8945

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