Summer Algal Bloom: State of Play in the District

Published: 09-Jan-2018

Health warnings are in place for the Ashley River in the immediate surrounds of the Rangiora-to-Loburn Bridge, and in the area of the State Highway One Bridge near Waikuku. There are no other health warnings in activation for waterways across the District at this time.

Lake Pegasus, which has been a source of regular algal bloom activity at this time of the year in the past, is being closely monitored. Algal Bloom

The lake is not currently affected by algal bloom and has a clean bill of health at this time.

The warning affecting the Ashley River in the area in the immediate surrounds of the Rangiora-to-Loburn Bridge was given in the week prior to Christmas, relating to space 150 metres either side of the bridge.

A further warning was issued on the surrounds of the State Highway One Bridge near Waikuku after Christmas.

Both areas covered by the health warnings are sign posted.

Other areas of the river, such as the Ashley gorge, are safe for swimming.

People and animals should remain out of the waterways until the warnings have been lifted.

Environment Canterbury is monitoring the sites.

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
  • 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.
  • While the health warnings are in place avoid contact with the water

Name: Matt McIlraith

Phone: 0800 965 468