MEDIA RELEASE
April 3, 2014
Health warning for SH1 on Hurunui River lifted
The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health
warning issued for State Highway One (SH1) on the Hurunui River / Rakahuri. This was issued on the 26 February 2014.
Recent surveys at SH1 on the Hurunui River / Rakahuri have shown the cover of potentially toxic blue-green algal mats
(benthic cyanobacteria) in the river has decreased and cover is now below the levels that are of concern to public
health.
Dr Alistair Humphrey, Canterbury Medical Officer of Health, says Environment Canterbury’s sampling for the summer season
has now stopped and therefore the public will need to be aware of the potential for algal blooms themselves.
“The growth of algal mats is, however, less likely because of the cooler weather and the seasonal nature of the blooms,”
Dr Alistair Humphrey says.
“Environment Canterbury will resume sampling again next summer when there is an increased likelihood of cyanobacterial
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, hence the need for people/ dog-walkers to treat every low-flowing river cautiously.
• Exposure to an algal bloom can cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth
and fingertips. If you experience any of these symptoms visit your doctor immediately and please let your doctor know if
you have had contact with lake water when there is a health warning in place.
For further information visit http://ecan.govt.nz/services/online-services/monitoring/swimming-water-quality/Pages/river-warnings.aspx
Or contact Community and Public Health on (03) 364 1777.
ENDS