Sewage pouring into city rivers
Eight-billion litres of untreated wastewater, including raw sewage, has poured into Christchurch's waterways since the earthquakes.
Experts say unless more money is made available to fix the cracked underground pipes, the sewage leaks could continue for another 10 years.
Christchurch City Council water and waste manager Mark Christison said the council did not have enough money to fix the problem and unless it received a cash injection, the sewerage overflows were likely to continue.
The system had 114 built-in overflow points, which allowed wastewater to be released in emergency situations. These had been used more frequently since the quakes to keep sewage out of people's homes and off roads, Christison said.
The council and the Crown are splitting the cost of repairing and rebuilding the city's damaged horizontal infrastructure, including the wastewater system. To date, the Crown has agreed to contribute $1.8 billion and the council $1.14b, but the council has long maintained that at least an extra $400m will be needed if all the necessary work is to be done.
Earlier this month, Canterbury medical officer of health Alistair Humphrey described Christchurch's urban waterways as "open sewers" and warned people not to eat whitebait from the Avon and Heathcote rivers.
University of Canterbury professor Bryan Jenkins, who specialises in strategic water management, said the situation was bleak.
The waterways could get 10 to 12 more years of filthy wastewater.
Even if the infrastructure was restored to pre-quake standards, it would not completely solve the issue. Sewage would still overflow to "unacceptable levels".
Historically, some sites overflowed once every two or three months, Jenkins said.
"Even if it gets back to pre-earthquake levels, you have unacceptable levels of water quality degradation if you want to use it for recreational purpose or for food gathering/mahinga kai."
Jenkins said there was still "a chance for recovery" for waterways but it would require more money. Options for improvement included overflow storage, constructed wetlands in the red zone and removal of sediment.
Green Party MP Eugenie Sage said raw sewage pumping into waterways should be more of a priority to the Government than building "super-sized convention centres and stadiums".
- The Press