What’s the story: Christchurch Wastewater Treatment Plant smell
We know many areas across central Ōtautahi Christchurch are currently being affected by unpleasant smells coming from the Christchurch Wastewater Treatment Plant in Bromley.
As the environmental regulator, it’s our responsibility to ensure impacts like this are understood and addressed, and we acknowledge the real strain the stench is placing on people’s daily lives.
The facts - what’s happening right now
Our team is working closely with Christchurch City Council (CCC) to resolve the current problem operationally at the treatment plant and get a solution in place.
- CCC has advised us that heavy rainfall this month has significantly affected the health of several oxidation ponds.
- Monitoring on 26 January showed a drop in dissolved oxygen (DO) levels across the system. Low oxygen conditions make smells far more likely, particularly in Ponds one, two, and three, which are currently the most affected.
- The ponds are also under extra pressure from higher than usual loading and patches of sludge rising to the surface, further increasing the chance of smells escaping into nearby communities.
Our officers are speaking face-to-face with affected communities in east Ōtautahi Christchurch
Christchurch Wastewater Treatment Plant operations teams are closely monitoring conditions and responding wherever possible to improve pond health and minimise smell. This includes:
- Adjusting flows through the ponds to stabilise loading.
- Regular monitoring so we can react quickly to changes.
- Using all available operational tools to support oxygen levels and improve pond performance.
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What we are doing
Our first priority is to ensure the smells are controlled as fast as possible. We have issued a formal request for CCC to provide confirmation of the actions they are taking and timeframes to rectify the current situation and address the smells.
This will also include a requirement for CCC to set out the proactive actions they will take to mitigate the potential for any future smell issues.
We are also actively considering what, if any, punitive enforcement action may be appropriate and in the public interest.
At present, CCC are working closely with us to address the issue. However, any delays in taking effective and timely action will likely result in the use of statutory notices to compel action.
As the plant is a critical piece of public infrastructure, our current enforcement approach is to work with CCC on improving smell as soon as possible. This approach doesn’t lessen our commitment to expecting compliance, and the issue continues to be under investigation.
Managing and monitoring discharges to air in our region, including smells, is part of our responsibilities as a regulator under the Resource Management Act (RMA) and the Canterbury Air Regional Plan.
What happens next
We will continue to work closely with CCC to ensure they are meeting their consent conditions and putting smell mitigation measures in place wherever practicable.
Report a smell
Your reports are an essential part of this work. They help us understand what you’re experiencing in real-time and guide the timing and location of our monitoring.
If you notice strong, unusual, or unpleasant smells, please continue to report it through the Smelt It app, or on 0800 765 588 (24 hours)
Advice from the National Public Health Service
Feeling unwell from the smell? We have checked in with Health NZ Te Whatu Ora and here's their advice from Dr Annabel Begg, Medical Officer of Health for the National Public Health Service:
- Exposure to hydrogen sulfide odour arising from the Christchurch wastewater treatment plant can cause nausea, headaches, eye and throat irritation, skin irritation, sleep disturbance, and worsening asthma symptoms at relatively low concentrations.
- If people exposed to the odour don't experience physical health effects, continued exposure to unpleasant or nasty, noxious odours can still have an adverse effect on people's mental wellbeing.
- While exposure to hydrogen sulphide is unpleasant and may result in health effects, it doesn’t accumulate in the body. Any health effects would be expected to resolve when the odours are brought back to normal levels, and long-term health effects are highly unlikely.
- People experiencing health issues as a result of the smells coming from the treatment plant should seek health advice from their GP, doctor, Hauora or healthcare provider, or call Healthline free on 0800 611 116, anytime 24/7 for advice as soon as possible. In an emergency call 111.