Ōhau Channel Diversion Wall: What's the Issue?
The Ōhau Diversion Wall, which was built in 2008, aimed to divert nutrient-rich water from Lake Rotorua to Lake Rotoiti. It has been instrumental in bringing Rotoiti back to health for many years by significantly reducing algae and clarifying the water.
Holes have appeared and are widely noticeable from the surface, with reports of erosion occurring six years into the installation that was said to last 50 years. These breaches effectively take the water from Lake Rotorua and tap it directly into Lake Rotoiti, thereby reversing any gains made in past years. Flow monitoring in 2024 reconfirmed the presence of a two-way flow, which indicates that the wall is no longer functioning as originally intended.
Most Recent News
Why It Matters
Lake Rotoiti's health has again become a matter of concern. We are witnessing the consequences of this, like the reappearance of cyanobacterial blooms in some places. If the situation remains the same, the community could be facing a loss of the environmental improvements made since 2008. These include better biodiversity, clearer water, and safer swimming conditions.
On the other hand, the Bay of Plenty Regional Council (BoPRC) is the legal owner of the wall and is therefore responsible for its maintenance and repair. However, the local body has been aware of the situation for over ten years and goes against the conditions in the resource consent, which require the wall to be kept in "good condition."
Estimates show that the preferred long-term fix would cost up to $25 million. It encompasses removing the corroded steel sheet piles and replacing them with durable circular PVC modules (Combiloics) that are engineered to last up to 100 years and are low-maintenance, needing fewer inspections. The removed, damaged sheet piles would be recycled, minimising any adverse environmental impacts.
What's Being Done
The Lake Rotoiti Community Association (LRCA) actively supports the Fix Ōhau Wall campaign led by John Gifford and the Lakes Water Quality Society (LWQS).
Boprc has not taken action to solve the problem permanently, so community organisations want to hold the council responsible.
This is not just about a structure but our lake, environment, and shared future.
How You Can Help
- Read the latest reports and news from Fix Ōhau Wall and LWQS to stay current.
- You can be the voice for Rotoiti by sharing information on social media/apps and being there when it's time to speak up.
Visit Fix Ōhau Wall