At a Glance
The Motukawa Scheme makes use of 99 metres (m) of elevation difference between the Manganui and Waitara Rivers to drive three generating sets, the last one was added in 1938.
In recent years, we have made significant efficiency enhancements. In 2005, we installed a 200 kW turbine in the Motukawa water race, taking advantage of the natural fall in the supply race system. In 2007, we installed pumps to lift water about 4m out of the Mangaotea Stream into the Lake Ratapiko supply race. These improvements added to the scheme’s power output — and help make better use of the natural resource.
An upgrade project, which was completed in 2012, enhanced the efficiency of the Station by 15%. Our state-of-the-art computer fluid dynamics modelling, suggested an 8-10% efficiency gain will be achieved. The upgrade will also mean our equipment is set to perform for many years to come.
Environment and recreation
When there’s a lot of rain, the Scheme’s diversion canal drains an adjacent catchment so Lake Ratapiko, formed by the dam, rises to spilling level.
Eel and fish are currently unable to pass through the Scheme. However, there’s a successful trap and transfer programme for Longfin Eel, supporting the species’ migration. We are funding extensive riparian planting in catchment areas to improve water quality and fish habitat.
We gained new Resource Consents in 2001, consents will again be due for renewal in 2022.