14 November 2019

For immediate release

Health warning removed for algal bloom at Lake Forsyth/ Te Roto o Wairewa

Canterbury District Health Board’s Community and Public Health unit has lifted its algal bloom health warning issued for Lake Forsyth/ Te Roto o Wairewa on the 1 October 2019.

Recent water testing at Lake Forsyth/ Te Roto o Wairewa, has shown the quantity of potentially toxic blue-green algae (planktonic cyanobacteria) in the lake has decreased and concentrations are now below the levels that are of concern to public health.

Canterbury Medical Officer of Health Dr Alistair Humphrey says Environment Canterbury’s sampling of Lake Forsyth/ Te Roto o Wairewa will continue on a fortnightly basis.

“The public will be informed if testing shows that concentrations have increased and there is a risk to public health again, but at least this means people can fully enjoy Lake Forsyth/ Te Roto o Wairewa during show weekend,” says Dr Humphrey.

Facts about cyanobacteria:

• The algae occur naturally but can increase rapidly during warmer months.

• Algal blooms are caused by a combination of nutrients in the water (such as nitrogen and phosphorus), and favourable weather conditions (e.g. increased temperature, calm days).

• If the water is cloudy, discoloured, or has small globules suspended in it, avoid all contact.

• Not all cyanobacterial blooms are visible to the naked eye and toxins can persist after the blooms disappear.

• Cyanobacterial concentrations can change quickly with changing environmental conditions (e.g. wind). If a health warning is in place avoid contact with the water.

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

Or contact Community and Public Health on (03) 364 1777:

https://www.cph.co.nz/your-health/recreational-water/

For more information about Mahinga Kai:

https://www.cph.co.nz/wp-content/uploads/saf0112.pdf

ENDS

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