It has four 55.5 megawatt generating units, and a generation output of up to 212 megawatts.
Ōhau B generates enough electricity each year for about 115,000 average New Zealand homes.
Ōhau B is a twin station with Ōhau C, and both hydro stations have the same generating capacity and use similar equipment.
Water from Lake Ruataniwha flows through Ōhau B, then goes into the Ōhau C canal, which takes it to the Ōhau C power station and out into Lake Benmore.
The Ōhau B hydro station, the second to last hydro station to be commissioned on the Waitaki hydro scheme in 1984.
Ōhau B was built as part of the Upper Waitaki hydro scheme, which began in 1968.
The Upper Waitaki hydro scheme involved building four hydro stations, along with two dams and six canals totalling 56 kilometres.
Ōhau B and C were the last hydro stations to be built on the Waitaki hydro scheme, completing the scheme 56 years after construction first began on the Waitaki dam and power station in 1928.