Review of the Benefits of the Okere Gates Control Structure - Lake Rotoiti

Human intervention to our lakes and channels can take many turns and result in profound immediate and long term ecological, cultural, environmental and public safety implications. Similarly, modification to existing structures also needs full and considered assessment before physical works / changes to operating regimes are implemented. Such is the case at Lake Rotoiti and its interface with the Kaituna River.

Lake Rotoiti outflows are currently regulated via the Okere Channel radial gates to control lake levels within a target band. Lake levels in Rotoiti can also potentially impact on inflows from Lake Rotorua via the Ohau Channel and hence possibly also Lake Rotorua levels. As the resource consent for the Okere gates expire June 2010 it is imperative that EBOP fully understand the impacts any new operating regime will have.

Aurecon developed a hydraulic model of this two lake system. Alternative outlet structures were tested on the Okere channel for the period 1998 to 2007 and lake levels and outflows were compared with the 10 year historical record. Potential benefits / impacts for stakeholders including iwi, lake ecology, bach owners, fishing and white water rafting were examined. This modelling has provided a sound platform to inform the consultation process.