Health warning removed for algal bloom at the Ashley/Rakahuri River at State Highway 1 and the Rangiora-Loburn Bridge
The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health
warning issued along the Ashley/ Rakahuri River at State Highway 1 and at the Rangiora-Loburn Bridge.
Recent cyanobacteria surveying of the water in the Ashley/Rakahuri River has shown the coverage of potentially toxic
blue-green algae (benthic cyanobacteria) in the river has decreased and are now below the levels that are of concern to
public health.
Canterbury Medical Officer of Health Dr Alistair Humphrey says Environment Canterbury’s sampling of the Ashley/Rakahuri
River will continue to the end of this summer and then will resume next summer when there is increased likelihood of
cyanobacteria growth.
The algae occur naturally but can increase rapidly during warmer months – river users are advised to treat every low-flowing river cautiously.
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, hence the need for people/ dog-walkers to treat every low-flowing river cautiously.
For further information visit https://www.ecan.govt.nz/your-region/your-environment/water/swimming-water-quality/
Or contact Community and Public Health on (03) 364 1777.
For more information on Mahinga kai:
ENDS