Health warning lifted for Te Roto O Wairewa Lake Forsyth

Wednesday May 10, 2017

​The Community and Public Health division of the Canterbury District Health Board has lifted its algal bloom health warning issued for Te Roto o Wairewa/Lake Forsyth on 18 January 2017.

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

Dr Alistair Humphrey, Canterbury Medical Officer of Health, says Environment Canterbury's sampling of Te Roto o Wairewa/Lake Forsyth will continue to be monitored on a monthly basis and the public will be notified if there is a risk to public health again.

Facts about cyanobacteria:

  • The algae occur naturally but can increase rapidly during warmer months.
  • 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.
  • If a warning is in place, people and animals should not drink the water from the lake at any time, even boiled water.
  • Exposure to an algal bloom can 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 lake water when there is a health warning in place.​

For further information visit https://www.ecan.govt.nz/your-region/your-environment/water/swimming-water-quality/ or contact Community and Public Health on (03) 364 1777.

Page last reviewed: 10 May 2017
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