Media Release
Issued: [05 January 2024]
Health Warning – Algal Bloom in Lake Pegasus
Te Mana Ora | Community and Public Health has issued a health warning after potentially toxic blue-green algae (planktonic cyanobacteria) was found in Lake Pegasus.
People should avoid the Lake and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted.
The type of cyanobacteria that is currently present is Dolichospermum (formerly called Anabaena) which can be present as green globules floating in the water column or form surface scums or sheens.
Dr Cheryl Brunton, Medical Officer of Health of Te Mana Ora, National Public Health Service, says the algal bloom can produce toxins harmful to humans and animals. “People should avoid contact with the water until further notice.”
“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 and please let your doctor know if you have had contact with the lake water”, Dr Brunton says.
No one should drink the water from the lake at any time. Boiling the water does not remove the toxin.
Animals that show signs of illness after coming into contact with algal mats or scums should be taken to a vet immediately.
“When a bloom of potentially toxic cyanobacteria is present in a lake, there is a possibility of cyanobacteria and toxins being transported downstream. People are advised to avoid contact with the downstream water bodies,” says Dr Brunton.
Environment Canterbury monitors the lake weekly during summer and the public will be advised of any changes in water quality that are of public health significance.
Warning(s) to avoid the following waterway(s) due to ongoing algal blooms is/are still in place.

For further details visit: https://www.lawa.org.nz/explore-data/canterbury-region/

--- Update. As we reported in Aoraki > News > Another-change-of-location-for-south-island-champs-2024, "Lake Pegasus is now getting very close to having the all clear from Ecan, the Christchurch DHB, Waimakariri District Council etc, but the earliest we would hear is Tuesday 5th [March], leaving just 3 days [before South Islands] to prepare." ---