Lake Rotoiti is under threat. The Ōhau Wall, built to protect it from polluted Lake Rotorua inflows, is failing. Urgent repairs are needed to stop further damage and safeguard the lake’s future.
Fix Ōhau Wall is a community-led initiative to restore this vital structure and ensure a cleaner, healthier future for Lake Rotoiti and generations to come.
The wall was built in 2008 to last 50 years. By 2014, corrosion was evident. By 2022, the wall was leaking. And now, in 2025, still no fix.
Without formal action water quality will continue to decline.
The wall is still the property of the Bay of Plenty Regional Council, which has a moral and legal environmental duty to look after it.
No delays, no excuses. Fix the wall. Protect the lake. Stand with us, join the cause!
John Gifford, Chair of the Lakes Water Quality Society, speaks with Stephanie Arthur-Worsop about the challenges facing Lake Rotoiti and the importance of protecting its future. Watch our video to learn more.
why this is critical
Critical part of the overall Rotorua lakes restoration programme
Historic improvements to Lake Rotoiti have reversed
Strong likelihood of severe constraints on amenity values
The Councils obligation to maintain in “good condition”
Lake Rotorua water quality is not compatible with Lake Rotoiti
Not meeting the Regional Plan statement target in Lake Rotoiti
The Ballad of the Ohau Wall
A must-listen to help save our lake!
The Statistics
This graph highlights the decline in water quality since 2012.
The Impact - Algae Bloom
Blue-green algae, which grow rapidly in phosphorus and nitrogen-rich environments, release toxins that can harm human and animal health.
One algae bloom event, caused by the wall’s leakage, caused red-mode cyanobacteria warnings, and green scum also covered parts of the lake in November 2024.
When algae blooms begin to degrade, they affect the lake’s aesthetic and recreational value, emit odours, can trigger fish kills, and sap oxygen in the lower layers of the lake.
Water-based recreation is restricted, tourism appeal declines, and the preservation of this natural resource is compromised.
For a lake system culturally and ecologically significant as Rotoiti, the long-term impacts of sustained eutrophication would be severe.
current state of the wall
Ōhau Diversion Wall, the backbone of Lake Rotoiti’s defence, has deteriorated, with holes now clearly visible from the surface, and they are anything but small. The signs of structural damage are apparent, and the longer we wait, the bigger the harm to the lake and the loss of community trust will be.
who is responsible
The Ōhau Diversion Wall is a property of the Bay of Plenty Regional Council (BoPRC), the legal owners responsible for all operations, maintenance, and compliance with the conditions of resource consents.
Investigations were carried out to find suitable maintenance solutions, and the council must abide by the consent rules (RM16-0527), which specify that the wall must be maintained and kept in “good condition” to conserve the lake’s water quality.
Unfortunately, despite the council’s awareness of the structure’s problems, the wall has not been permanently repaired for over ten years.
Community organisations will hold the council responsible.
what’s the solution?
Our preferred fix involves removing the corroded steel sheet piles and replacing them with durable circular PVC modules (Combilocs).
- Engineered to last up to 100 years – providing a reliable, future-proof barrier between the lakes
- Low maintenance – once installed, it will require only periodic inspections
- Environmentally sound – damaged sheet piles will be removed and responsibly recycled, minimising environmental impact
- Estimated cost - up to $25 million, an investment in the long-term health of Lake Rotoiti
Help Us Spread Awareness
Keep up to date with the latest from Fix Ōhau Wall, fill in your details below to subscribe, or follow the Lake Rotoiti Community Association Facebook page.
Important articles & Documents
Explore articles and documents illustrating the truth and the crisis resulting from the Ōhau Diversion Wall’s degradation. The materials outline the technological, ecological, and social aspects that require intervention now.
Letter of Demand BoPRC - July 2025
File Size: 8.18MB
LWQS - Presentation-BoPRC Ohau Channel Wall - December
File Size: 8.18MB
David Hamilton 2009
File Size: 887KB
RM16-0527 Consent Conditions FINAL
File Size: 468KB
Ohau Wall Water Quality Annual Monitoring Report 2018 - 24
File Size: 3.97MB
Ohau Diversion Wall 7 year Review - Report
File Size: 2.48MB