Journey with me into the heart of Auckland’s waterworks. We are about to explore the historic Huia Dam Intake Tunnel. This tunnel is a crucial part of the Waitākere Ranges Water Supply System.
A good water supply is essential. Early Auckland greatly improved public health after introducing piped water from Western Springs in 1877. The Waitākere Ranges became vital. The Huia Dam Intake Tunnel helped bring water to Auckland.
The Waitākere Ranges boast high rainfall. Much of this water flows to the city without pumping because of gravity. The Huia water supply, along with supplies from the Hunua Ranges and Waikato River, significantly boosted Auckland’s growth.
The Waitakere Ranges Water Supply System taps into the Huia, Nihotupu and Waitakere streams. A series of five large dams were constructed throughout the 20th century. Reservoirs, tramways, piping, tunnels and filter stations were built. All these structures provided access to the water catchment. They also created a gravitational water supply into Auckland.
Let’s talk about the dams. These main structures are still in use today. The Waitakere Dam was completed in 1910. The Upper Nihotupu Dam followed in 1923. The Upper Huia Dam was finished in 1929. Then came the Lower Nihotupu Dam in 1948. Lastly, the Lower Huia Dam was completed in 1971.
The first three dams are concrete gravity dams. The latter two are earth dams. The Waitakere Dam was among New Zealand’s first large-scale concrete dams. The Lower Nihotupu Dam holds the distinction of being the country’s first earth dam.
The Waitakere Ranges Water Supply System is very significant. The structures show the evolution of New Zealand dam theory, techniques and materials in the 20th century.
Many notable engineers contributed to this system. These include Hugh Munro Wilson, James Carlaw, Walter Ernest Bush and Cyril Firth. Each played a role in shaping Auckland’s water infrastructure.
Driving down Woodlands Park Road from Scenic Drive offers a glimpse of the historic Huia Aqueduct. Built in the 1920s, it still supplies water to the Huia Water Treatment Plant.
Arthur Mead, later city Waterworks Engineer, conceived the aqueduct. He proposed it run from Piha south to Whatipu and Huia. It would collect water from streams along the way. His supervisors opted to focus on the Hunua scheme instead.
The Huia Tunnel Aqueduct spans 1200 meters between the Huia and Nihotupu valleys. The Huia Conduit is a 2.4 km reinforced concrete box structure. Part of it is tunneled. Some sections are above ground, with bridges crossing streams.
Other dams were eventually connected to the aqueduct. The Lower Huia is pumped 100 meters vertically to join the Upper Huia water. Water from the Lower Nihotupu Dam is pumped 113 meters vertically to join at Mackies Rest.
In 1999, Watercare received the Arthur Mead award for upgrading the Aqueduct. This award recognizes projects that protect or enhance the environment.
The Huia Dam Intake Tunnel stands as a testament to innovative engineering. It highlights the ongoing effort to provide Auckland with a reliable water supply. As we conclude our visit, consider the ingenuity required to bring this essential resource to a growing city. The Huia Dam Intake Tunnel is a vital piece of Auckland’s history and infrastructure.