Ōhau A hydro station
Ōhau A is a hydro station located in the Mackenzie Basin, South Canterbury, New Zealand.
It has four 66 megawatt generating units, and a generation output of up to 264 megawatts.
Ōhau A generates enough electricity each year for about 144,000 average New Zealand homes.
The Ōhau A power station is located at the end of the manmade Pūkaki canal. The Pūkaki canal joins with the Ōhau canal to meet the water flows from Lake Ōhau and Lake Pūkaki.
Building Ōhau A
Ōhau A was the second station built as part of the Upper Waitaki hydro scheme. The scheme began in 1968, when Twizel township was established.
The Upper Waitaki hydro scheme involved building four hydro stations, along with two dams and six canals totalling 56 kilometres.
During construction of Ōhau A, approximately two million cubic metres of rock and gravel was excavated from the northern bank of the Ōhau River. That’s about half a million concrete truck loads.
Another half a million cubic metres was removed for the tailrace – the tunnel that channels the water out of the station.
During the building of Ōhau A, Mr Max Smith, the locally based Project Engineer of the Upper Waitaki Power Project, came up with the idea of creating a rowing course in Lake Ruataniwha.
Work went ahead on the course – and it’s now a national venue for rowing.
Ōhau A fully operational
About 15,000 truck loads of steel plate was used to build the four penstocks that channel water into Ōhau A power station.
The Ōhau A penstocks were built in 21-metre sections with a diameter of 5.8 metres, and weigh 59 to 63 tonnes each.
A view of Ōhau A, looking west, with Unit 4 in the foreground.