Health warning removed for algal bloom in the Hurunui River at State Highway 1
The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health
warning issued along the Hurunui River at State Highway 1. This was issued on the 12th January 2017.
Recent cyanobacteria surveying for the Hurunui River at SH1 has shown a decrease in potentially toxic blue-green algae
mats (benthic cyanobacteria) in the river and the cover is now below the levels that are of concern to public health.
Canterbury Medical Officer of Health Dr Alistair Humphrey says Environment Canterbury’s monitoring of the Hurunui River
will continue to the end of this summer and then will resume next summer when there is increased likelihood of
cyanobacteria growth.
A warning remains in place for the Hurunui River near SH7.
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.
ends