ARAPUNI HYDRO STATION

The Arapuni Dam is the oldest Mercury dam (in operation). It was built between 1924 and 1929 and was the first government-built high dam on the Waikato River. It is recognised for its engineering significance and is a listed historic heritage item.

ARAPUNI DAM ENHANCEMENT PROJECT

An engineering study shows the Arapuni Hydro Dam is safe and fit for everyday use, but work needs to be done to improve the left abutment to protect it from the risk of water seepage.

Opened: 1929
Number of generating units: 8 Francis Turbines
Total Output: 198MW
Average Annual Output: 870GWh

Units 1-4 (also known as the North end units) were built first.
Units 5 and 6 were commissioned in 1938 and 7 and 8 in 1946.

Units 5-8 were replaced and recommissioned in 2012-2013.

Diagram of Aparuni dam and hydro station

Over the life of the dam there have been several improvements made to the seepage controls, with the most recent in mid-2005.
This involved remediation work to construct a concrete cut-off wall under the dam, without disrupting power generation or causing environmental damage. This was a pioneering effort in the field of dam engineering.

We have identified that work needs to be done to improve the left abutment and protect it from the risk of water seepage and internal erosion. We started early works in 2024. Read more about the Arapuni Dam Enhancement Project here.