From CDHB: Health Warning - Algal bloom in Hakatere/Ashburton River at Boundary Road

Published: 16 February 2021

Share this article

Canterbury DHB’s Community and Public Health unit has issued a health warning for the Hakatere/Ashburton River at Boundary Road and at the hapua (river mouth).
The warning follows the finding of exposed and detaching mats of potentially toxic algae (benthic cyanobacteria) at these locations along the river.
Warnings also remain in place for the Hakatere/Ashburton River at Hills Road and SH1.
People should avoid these areas and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted.
Dr Ramon Pink Canterbury Medical Officer of Health, says the algae look like dark brown to black mats and can produce toxins harmful to people and animals.
“Exposure may 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, also let your doctor know if you’ve had contact with dark brown/black algal mats or water in this area,” Dr Pink says.
Pets that show signs of illness after coming into contact with algal mats should be taken to a vet immediately.
People and animals should remain out of the waterways until the warnings have been lifted.
Environment Canterbury is monitoring the sites and the public will be advised of any changes in water quality.
Facts about cyanobacteria:
  • Appears as dark brown/black mats attached to rocks along the riverbed.
  • A low cover of the algae can occur naturally but can increase rapidly during warmer months. Algal blooms are influenced by a combination of available nutrients in the water and sediments (such as nitrogen and phosphorus), a sustained period of low and stable flows, and favourable weather conditions (e.g. increased temperature, calm days).
  • It often has a strong musty smell and algal toxin concentrations can vary over short periods.
  • 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
Or contact Community and Public Health on (03) 364 1777:
For more information about Mahinga Kai:

Follow Us

Upcoming meetings

Council

15 December 2021, 1.00 pm


Council

1 December 2021, 1.00 pm


BOARD: Methven Community

29 November 2021, 10.30 am


Council

17 November 2021, 1.00 pm


COMMITTEE: Audit & Risk

10 November 2021, 1.30 pm


Road Closures

FESTIVAL OF PIPE BAND MUSIC

from 13 Feb 12:30 to 13 Feb 13:30


GILLS ROAD

from 30 Jan 6:00 to 30 Jan 18:00


WALNUT AVENUE

from 13 Dec 7:00 to 17 Dec 18:00


TARBOTTONS ROAD

from 30 Nov 6:00 to 2 Dec 19:00


WALNUT AVENUE + EAST STREET INTERSECTION

from 29 Nov 19:00 to 4 Dec 6:00


View all Road Closures | Live map

More News

View all news