à Âhau B is a hydroelectric power station in the Mackenzie Basin, Canterbury, New Zealand. Operated by Meridian Energy, it is one of the three à Âhau stations in the Upper Waitaki hydro scheme. It is a twin station to à Âhau C, and water from Lake Ruataniwha passes through à Âhau B before entering the à Âhau C canal on its way to à Âhau C and Lake Benmore.
à Âhau B was built as part of the Upper Waitaki hydro scheme, which began in 1968. Construction of the station began in 1977 and it became fully operational in 1984.
Lake Ruataniwha, from which à Âhau B draws its water, was created during the Upper Waitaki works by damming the à Âhau River.
à Âhau B has four 53-megawatt generating units with a total installed capacity of 212 MW. It was designed as a twin station to à Âhau C, with the two stations having similar equipment and the same generating capacity. The 2025 WSP hydro-schemes report states that each of the two twin stations produces approximately 958 GWh of electricity annually.