Health Warnings Lifted for Ashley Rivers

Friday March 15, 2013

The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health warnings issued along the Ashley River.
These were issued in December 2012 and January 2013 for SH1 Bridge and the Rangiora / Loburn Bridge respectively.
Dr Ramon Pink, Canterbury Medical Officer of Health, says recent surveys along the Ashley River have shown that the quantity of potentially toxic blue-green algae (benthic cyanobacteria) in the river has decreased to below levels that are of concern to public health.
Dr Pink says Environment Canterbury’s sampling 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.
  • 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. It is important to treat every low-flowing river cautiously, especially keeping dogs away as the algae can be particularly harmful to them. 
Or contact Community and Public Health on (03) 364 1777.
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Page last reviewed: 09 July 2013