Health warning removed for algal bloom on the Ashburton River

The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health warning issued for the Ashburton River at State Highway 1.

Recent river bed surveys have shown that the quantity of potentially toxic blue-green algae (benthic cyanobacteria) in this river has decreased below levels that are of concern to public health.

Warnings to remain out of waterways due to ongoing algal blooms are still in place at:
Te Waiwera/Lake Forysth
Te Waihora / Lake Ellesmere
Lake Pegasus
Ashley River at SH1

The public will be notified when the above sites have been cleared by Environment Canterbury monitoring.

Canterbury Medical Officer of Health Dr Alistair Humphrey says Environment Canterbury’s sampling of Canterbury’s rivers and lakes for Cyanobacteria has now stopped and will resume next summer. The public are reminded to keep a look out for cyanobacteria if swimming in rivers and lakes.

Facts about cyanobateria in rivers:

Appears as dark brown/black mats attached to rocks along the riverbed
The algae occur naturally but can increase rapidly during warmer months
It often has a strong musty smell and algal toxin concentrations can vary over short periods with changing environmental conditions
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 information visit http://ecan.govt.nz/services/online-services/monitoring/swimming-water-quality/Pages/river-warnings.aspx

ENDS

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