MARAETAI I & II HYDRO STATION

MARAETAI I
Opened: 1952
Number of generating units: 5 Francis turbines
Total Output: 180MW

MARAETAI II
Opened: 1970
Number of generating units: 5 Francis turbines
Total Output: 180MW

Average Annual Output (combined across Maraetai I & II): 880GWh

Maraetai I and Maraetai II were constructed in the same valley and are operated as one hydro station. The two have the largest capacity of any of the stations of the Waikato Hydro System. Each has five generation units and combined the average annual output is 880GWh; that’s enough to power the equivalent of 110,000 average homes every year.

Maraetai I was the third powerhouse built as part of the Waikato Hydro Electricity Scheme. It began generating energy in 1952 from three of its five turbines.

Maraetai II was the last of the hydro scheme projects to be constructed. Work began there in 1959 but was suspended in 1961 when a new government shifted priority to the Cook Strait cable project following a significant increase in electricity demand. The station wasn't completed until 1970.

Maraetai I has a variable radius concrete arch dam, which when constructed, was the largest purely hydroelectric dam in the Southern Hemisphere. The dam serves both the Maraetai I and II hydro stations. The spillway is a separate structure situated adjacent to the intake channel to Maraetai II with a concrete-lined tunnel between the stations.

Operationally, Maraetai I and II are considered to be a single station.