Lakes are a treasure of the Bay of Plenty region. We are partners of the Rotorua Te Arawa Lakes Programme, a partnership with Rotorua District Council and Te Arawa Lakes Trust, to preserve our lakes for present and future generations.

Ōkere Gates and Ōhau diversion wall

The Ōkere Gates were constructed in 1982 to regulate the flow of water from Lake Rotoiti into the Kaituna River. The Ōhau Weir was constructed in 1989 to control water level fluctuations in Lake Rotorua. Bay of Plenty Regional Council was granted resource consent to build the diversion wall structure in Lake Rotoiti. Read more below.

Both the Ōkere Gates and Ōhau Weir are man-made structures to help control water levels in lakes.

The Ōkere Gates were constructed in 1982 to regulate the flow of water from Lake Rotoiti into the Kaituna River. The Ōhau Weir was constructed in 1989 to control water level fluctuations in Lake Rotorua.

Bay of Plenty Regional Council was granted a resource consent for the ongoing operation of the Ōkere Gates and the Ōhau Weir on 26 March 2012 after consultation and negotiation with a number of key stakeholders.

Two kaitiaki groups and the Rotorua Te Arawa Lakes Operational Liaison Group provide a voice for the community. These two groups are supported by Council, to ensure interested community members can have input into the monitoring and management of the Gates and Weir.

If you would like more information about the operation of the Ōkere Gates or Ōhau Weir, please scroll down or download the frequently asked questions fact sheet or telephone the engineering team at Bay of Plenty Regional Council on 0800 884 880.

Cultural Management Plan for Ōkere Gates and Ōhau Weir:

Bay of Plenty Regional Council was granted resource consent to build the diversion wall structure in Lake Rotoiti. The diversion wall is designed to stop water flowing from Lake Rotorua into the main body of Lake Rotoiti, instead diverting it down the Kaituna River via the Ōhau Channel.

Most of Lake Rotoiti's problems are caused by nutrients flowing into it from Lake Rotorua, so the diversion wall will, over time, significantly improve the lake's water quality. Scientists say it will have little impact on Kaituna River quality.

The Ōhau Diversion Wall information sheet has information about the wall.

The wall

The diversion wall starts just south of the entrance to the Ōhau Channel which links Lake Rotorua and Lake Rotoiti. It runs 75 metres offshore parallel to State Highway 33 and extends to Te Akau Point (1275 metres). The diversion wall is driven into Rotoiti's lake bed and rises to just above lake level. It is made of large, precast interlinking concrete and steel wall segments designed to last for at least 50 years. There is a cap on top of the wall to discourage people from walking on it, for safety reasons.

The diversion wall cost approximately $10 million to build, funded by Bay of Plenty Regional Council and Central Government.

The final design of the structure was based on feedback from the public at various hui and public meetings, as well as comments received on questionnaires, and a number of technical studies. These studies include:

  • Water quality modelling.
  • Sediment transport modelling.
  • Hydrodynamic modelling of the lake.
  • Geotechnical investigations.
  • Assessment of effects on downstream water quality in the Kaituna River and Maketū Estuary.
  • Landscape and visual assessment.
  • Cultural assessment.
  • Ecological assessment, including effects on fish and water birds.

What the wall achieves

The wall diverts water currently flowing through the channel from Lake Rotorua into Lake Rotoiti, directly down the Kaituna River. Previously, about 40 percent of this water flows into the Kaituna River, mostly in summer. The rest of the year it flowed mostly into Lake Rotoiti.

The diversion wall prevents 180 tonnes of nitrogen and 15 tonnes of phosphorus entering the main body of Lake Rotoiti from Lake Rotorua each year through the Ōhau Channel.

See more information below regarding Lake Rotorua events, closures and health warnings.

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