Lake warnings

We monitor more than 100 popular recreational sites in Canterbury during summer. Health warnings are placed at sites where an increased risk of cyanobacteria or faecal contamination is present. Advisory notes may be present but are not an official public health warning.

Cyanobacteria can occur in any waterway, at any time, so it is important that you know what it looks like. Find out more about cyanobacteria in waterways and how you can protect yourself and your animals.

Faecal contamination poses a risk to health, check out LAWA’s swim smart checklist, to know what to check before you swim.

Te Waihora/Lake Ellesmere

24 December, 2017 - last updated 17 November 2020

The Community and Public Health division of Canterbury District Health Board has been advised that the dominant species of potentially toxic blue-green algae (planktonic cyanobacteria) found in Te Waihora/Lake Ellesmere has changed from the initial health warning issued on 24 December 2017.

The type of cyanobacteria that are currently present in high concentrations are:

  • Nodularia, which can appear as a thick surface scum or be suspended throughout the water.
  • Dolichospermum (formerly called Anabaena), which can be present as green globules floating in the water column or form surface scums or sheens.

People and animals, particularly dogs, should avoid Te Waihora/Lake Ellesmere until the health warning has been lifted.

Environment Canterbury monitors the lake fortnightly and the public will be advised of any changes that are of public health significance.

Lake Rotorua (near Kaikoura)

Last updated 8 March 2019

Long term water testing indicates that there is a regular bloom of the potentially toxic cyanobacteria Anabaena and/or Microcystis present.

There is a permanent health warning advising people to avoid contact with water at this lake.

Environment Canterbury continues to monitor the lake on a regular basis.