Environmental groups and medical officials in Canterbury say it is a potential health risk to increase the amount of sewage contaminated overflows into Christchurch rivers.
The Christchurch City Council wants to increase the frequency of stormwater overflows it is allowed to let into the Avon and Heathcote rivers from once every two years to once every six months.
A Canterbury Medical Officer of Health, Alastair Humphrey, says an increase would most likely lead to a greater risk of gastroenteritis.
A spokesperson for the Avon-Heathcote Estuary Ihutai Trust, Alex Drysdale, says more effluent in the water will mean there is more risk involved in using the rivers for recreational activities.
